Mining methods underground_mining

AtlasCopco2007
Second edition 2007
www.atlascopco.com
Printedmatterno.9851628901a
Mining Methods
in Underground Mining
MiningMethodsinUndergroundMining

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underground mining methods 1
Foreword
2 Foreword by Hans Fernberg M Sc
Mining Engineering, Senior Adviser,
Talking Technically
3 Trends in underground mining
7 Geology for underground mining
13 Mineral prospecting and exploration
17 Finding the right balance in exploration drilling
21 Underground mining infrastructure
25 Principles of raise boring
29 Mechanized bolting and screening
33 Mining in steep orebodies
39 Mining in flat orebodies
43 Backfilling for safety and profit
46 Atlas Copco rock bolts for mining
Case Studies
47 Innovative mining at Garpenberg
53 Changing systems at Zinkgruvan
59 Increasing outputs at LKAB iron ore mines
63 From surface to underground at Kemi
69 Mining magnesite at Jelšava
73 All change for Asikoy copper mine
77 Mining challenge at El Soldado
83 Pioneering mass caving at El Teniente
91 Boxhole boring at El Teniente
97 Modernization at Sierra Miranda
99 Mount Isa mines continues to expand
105 High speed haulage at Stawell
109 Sublevel stoping at Olympic Dam
115 Improved results at Meishan iron ore mine
119 Mechanized mining in low headroom at Waterval
121 Large scale copper mining adapted to lower seams
125 Underground mining of limestone and gypsum
129 Sub level caving for chromite
133 Getting the best for Peñoles
137 Keeping a low profile at Panasqueira
Front cover: Headframe at Australia´s Golden Grove mine.
All product names such as Boomer, Boltec, Simba, COP, Scooptram
and Swellex are registered Atlas Copco trademarks. For machine
specifications contact your local Atlas Copco Customer Center or
refer to www.atlascopco.com/rock
Contents
Produced by tunnelbuilder ltd for Atlas Copco Rock Drills AB, SE-701 91 Örebro, Sweden, tel +46 19 670 -7000, fax - 7393.
Publisher Ulf Linder ulf.linder@se.atlascopco.com Editor Mike Smith mike@tunnelbuilder.com Senior Adviser Hans Fernberg
hans.fernberg@se.atlascopco.com Picture Editor Patrik Johansson patrik.johansson@se.atlascopco.com
Contributors Marcus Eklind, Patrik Ericsson, Jan Jönsson, Mathias Lewén, Gunnar Nord, Björn Samuelsson,
all name.surname@se.atlascopco.com, Adriana Potts adriana.potts@ntlworld.com, Kyran Casteel kyrancasteel@aol.com,
Magnus Ericsson magnus.ericsson@rmg.se. The editor gratefully acknowledges extracts from Underground Mining Methods
– engineering fundamentals and international case studies by William A Hustrulid and Richard L Bullock, published by SME,
details from www.smenet.org
Designed and typeset by ahrt, Örebro, Sweden
Printed by WelinsTryckeri AB, Örebro, Sweden
Copyright 2007 Atlas Copco Rock Drills AB.
Digital copies of all Atlas Copco reference editions can be ordered from the
publisher, address above, or online at www.atlascopco.com/rock. Reproduction
of individual articles only by agreement with the publisher.

2 underground mining methods
Hans Fernberg
M Sc Mining Engineering
Senior Adviser
hans.fernberg@se.atlascopco.com
In history, before miners had access to productive equipment
and blasting agents, mining was hard and hazardous manual
work. The idea of excavating large volumes of rock to access
even the richest mineral zones was not feasible, and, as a re-
sult, ore veins were selectively followed, predominantly close
to the surface, or inside mountains. During the past century,
introduction of diesel power and electricity, combined with
new methods of mineral dressing, paved the way for large
scale open pit mining, and later for mechanized underground
mining. Nevertheless, the largest quantities of ore are still
excavated from surface deposits.
Atlas Copco, as an equipment supplier with a truly global
presence, has been at the forefront of technical and innova-
tive development. From pneumatic to hydraulic power, from
railbound to trackless haulage, from handheld to rig mounted
rock drills, and lately, from manual to computerized opera-
tion, Atlas Copco expertise is making mining safer and more
efficient.
Today, the mining industry, in its continuous battle for profit-
ability, is getting more and more capital intensive. Technical
development, especially in underground mining, has been
extremely rapid during the past decade. Less labour is re-
quired, and safety and environmental aspects are of prime
importance.
Growing demand for metals has resulted in today’s world wide
exploration and mining boom. However, mining companies
have experienced increasing difficulties in recruiting skilled
labour to work in remote mining communities. This has led
to a stronger involvement from contractors now carrying out
tasks beyond the more traditional shaft sinking operations.
Today, contractors get engaged in all kinds of mine infra-
structure works such as drifting, both inside and outside
the orebodies, and might also be involved in production and
mine planning, as well as scheduling. The miners, tradition-
ally focusing on maximizing the utilization of their equipment
mine-wide, are benefiting from experience gained by tunnel
contractors, who frequently have to concentrate their focus
on a single tunnel face. This makes the latter more suited for
high-speed ramp and drift development, and is one reason
why contractors are increasingly being employed by mine
owners on this type of work. Also, contractors bring with
them a range of skills developed under various conditions in
multiple locations, and frequently have the latest and most
sophisticated equipment immediately available. Gone are the
days when contractors got only the jobs that the mine manage-
ment could not do, or simply didn’t want to do. Nowadays, it
is normal for a contractor to bring specialist skills and equip-
ment to the project, and for the mine to get its development
work completed faster and cheaper than by doing it itself.
After all, when bringing mines to production, time and cost
are crucial factors in their viability.
When designing, manufacturing, selling and servicing Atlas
Copco equipment, we commit ourselves to achieving the high-
est productivity, and the best return on customer investment.
Only by being close to customers, by sharing their problems
and understanding their methods and applications, do we earn
the opportunity to be the leading manufacturer, and the natu-
ral first choice.
Our main ambition with this book is to stimulate technical
interchange between all people with a special interest in this
fascinating business. These include, in particular, underground
miners, managers and consultants, universities, and our own
sales and marketing organization.
The various cases from leading mines around the world illus-
trate how geological and geotechnical conditions, never being
identical, give birth to new and more successful variants of
mining methods. We hope that some of this material will
result in expanded contacts between mining companies in
their battle to be more competitive and profitable.
Foreword

Mining trends
Stable growth
Investments into new mines have in-
creased dramatically and all indicators
point to a continued high level of proj-
ect activities during the next couple of
years, see figure 1.
Whatever the investment activities
or metal prices, the amount of metal
produced every year in global mining
is fairly stable and increasing slowly but
steadily. Total volumes of rock and ore
handled in the global mining industry
amount to approximately 30,000 Mt/y.
This figure includes ore and barren rock
and covers metals, industrial minerals
and coal. Roughly 50% are metals, coal
about 45%, and industrial minerals
account for the remainder.
Dynamic growth in China.
Trends in underground mining
Boom time in
mining
The mining boom continues
unabated. After a difficult ending
to the 20th century, with metal
prices trending downwards
for almost 30 years, the global
mining industry recovered in
the early 2000s. Some observers
claim that the industry will see a
long period of increasing metal
prices and, although develop-
ments will continue to be cyclical,
there are predictions of a “super
cycle”. Already it is obvious that
the present boom is something
extraordinary in that it has lasted
longer than previous booms in
the late 1970s and the early 1950s.
An almost insatiable demand for
metals has been created by the
unprecedented economic growth
in several emerging economies
led by China, with India and
Russia trailing not far behind. The
distribution of the value of metal
production at the mine stage is
shown in figure 2 on page 4 page.
China and Australia are competing
for first place with roughly 10 per-
cent each. Some economic theo-
retitians, active during the late
1980s, who claimed that econo-
mic growth could take place with-
out metals have been proved ut-
terly wrong.
5 000
2001 2002 2003 2004 2005 2006
10 000
15 000
20 000
25 000
30 000
M USD
Figure 1: Mining projects under construction. (Raw Materials Data 2007)
Trends
Trends

Mining trends
Metal ore
Global metal ore production is around
5,000 Mt/y. Open pit mining accounts
for some 83% of this, with underground
methods producing the remaining 17%.
Barren rock production from under-
ground operations is small, not exceed-
ing 10% of total ore production, but the
barren rock production from open pit
operations is significant.
Open pits typically have a strip ratio,
the amount of overburden that has to be
removed for every tonne of ore, of 2.5.
Based on this assumption, the amount
of barren rock produced can be calcu-
lated as some 10,000 Mt/y. In total, the
amount of rock moved in the metals mi-
ning business globally is hence around
15,000 Mt/y. The dominance of open pit
operations stems in terms of the amounts
of rock handled, to a large extent, from
the necessary removal of overburden,
which is often drilled and blasted.
By necessity, the open pit operations
are larger than the underground ones.
The map below shows the distribution
of metal ore production around the
world, and also the split between open
pit and underground tonnages.
Open pit vs underground
There was a slow trend in the late 20th
century towards open pit production.
Two of the most important reasons for
this were as follows:
Lower ore grades
Due to depletion of the richer ore
bodies, the higher-cost underground
extraction methods are not economic.
See the figure below.
New technologies
The more efficient exploitation of lower-
grade deposits using new equipment and
new processes, such as the hydrometal-
lurgical SX-EW methods for copper
extraction, has enabled companies to
work with lower ore grades than with
traditional methods.
Future
Development of new mining technolo-
gies is driven by a range of underlying
factors, which affect all stakeholders.
Mines are getting deeper and hotter, and
are now more often located in harsh en-
vironments.
Legislation, particularly concerning
emissions, and increased demands on
Metal shares of total value gold copper iron ore nickel lead zinc PGMs diamonds other
karta sid 2.pdf 9/18/07 9:05:34 PM
Value of metal production at mines. (Raw Materials Data 2007)
open pit underground
898/77 Mt
1319/117 Mt
750/185 Mt
401/188 Mt
244/175 Mt
455/85 Mt
Total 5 000 Mt
Europe + Russia
Metal ore production from open pits (green), underground (red). (Raw Materials Data 2005)

Mining trends
noise and vibration, affect the miners
and equipment operators. Safety de-
mands have already completely changed
some unit operations, such as rock bolt-
ing and scaling. Similar developments
will continue.
Customers demand higher productiv-
ity, and there is an increasing focus on
machine availability and simpler service
procedures in order to reduce down-
time. Reduction of internal development
and production costs by the equipment
manufacturer promotes new technolo-
gies, as does competition from other
suppliers. In the early years of the 21st
century, new efficient underground me-
thods and equipment have made it
possible to turn open pit mines that had
become uneconomical because of their
depth into profitable underground ope-
rations. The orebody in these mines is
usually steep dipping, and can be mined
with the most efficient block caving meth-
ods. The competition for land in some
densely populated countries has further
meant that underground mining is the
only viable alternative. Such developments
have halted the growth of open pit mi-
ning and it is projected that the pre-
sent ratio 1:6 underground to open pit
mining will continue in the medium
term.
Magnus Ericsson
Raw Materials Group
Rock production (2005)
Ore
(Mt)
Waste
(Mt)
Total
(Mt)
%
Metals
Underground 850 85 935 3
Open pit 4 130 10 325 14 500 47
Total 4 980 10 410 15 400 50
Industrial minerals
Underground 65 5 70 0
Open pit 535 965 1 500 5
Total 600 970 1 570 5
Sub total 5 600 11 400 17 000 55
Coal
Underground 2 950 575 3 500 12
Open pit 2 900 7 250 10 000 33
Total 5 850 7 825 13 500 45
Overall total 11 450 19 225 30 700 100
Assumptions: 10% waste in underground metal and industrial mineral operations. Strip ratio (overburden/ore) in open
pit metal operations is 2.5. The strip ratio in industrial minerals is 1.8. For coal, underground barren rock is set at 20%, and the strip
ratio in open-pit mines is 2.5. Industrial minerals includes limestone, kaolin, etc. but excludes crushed rock and other construction
materials. Salt, dimensional stones, precious stones are not included. Diamonds are included in metals.
2500
2000
1500
1000
1930 1945 1960 1975 1988 1991 1994 1997 2000
Oregrade(%)
500
0
2
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
Copper/oremetal
production(mt)
Copper production Ore production Copper ore grade

Mining trends
Bingham Canyon copper mine near Salt Lake City, Utah, USA.

Geology for Mining
The earth’s crust
The earth’s crust consists of a variety
of rocks, formed under different cir-
cumstances, and with a wide variety of
properties. Rocks usually consist of one
or more minerals, ranging from single
chemical elements to complex com-
pounds. There are known to be more
than 3,000 different minerals.
Of the 155 known elements, some of
which do not occur naturally, oxygen
is by far the most common, making
up about 50% of the earth’s crust by
weight. Silicon forms about 25%, and
the other common elements such as alu-
minium, iron, calcium, sodium, potas-
sium, magnesium and titanium build up
the total to 99% of the earth’s crust.
Silicon, aluminium and oxygen oc-
cur in the commonest minerals such as
quartz, feldspar and mica, which form
part of a large group known as sili-
cates, being compounds of silicic acid
and other elements. Amphiboles and py-
roxenes contain aluminium, potassium
and iron. Some of the earth’s common-
est rocks, granite and gneiss, are com-
posed of silicates.
Oxygen also occurs commonly in
combination with metallic elements,
which are often important sources for
mining purposes. These compounds
can form part of oxidic ores, such as
the iron ores magnetite and hematite.
Sulphur also readily combines with
metallic elements to form sulphide ores,
including galena, sphalerite, molybde-
nite and arsenopyrite.
Other large mineral groups impor-
tant in mining include halogenides such
as fluorite and halite, carbonates such
as calcite, dolomite and malachite, sul-
phates such as barite, tungstates such
as scheelite, and phosphates such as
apatite.
Rarely, some elements can occur na-
turally without combination. The im-
portant ones are the metals gold, silver
and copper, plus carbon as diamonds
and graphite.
Minerals
In some circumstances, the properties
of individual minerals can be impor-
tant to the means of mining, and will
certainly be important for the means
of extraction of the materials to be ex-
ploited. More often, however, minerals
will be mixed with others to form the
various types of rocks, and the pro-
perties will be combined to form both
homogenous and heterogeneous struc-
tures. Feldspar accounts for almost
50% of the mineral composition of
the earth’s crust. Next come the pyrox-
ene and amphibole minerals, closely
followed by quartz and mica. These
minerals all make up about 90% of the
composition of the earth’s crust.
Minerals have a wide variety of pro-
perties that can be important in their
usefulness to man, and to the best way
Geology for underground mining
Importance of
geology
A thorough understanding of the
geology of a mineral deposit is
fundamental to its successful
exploitation, and this is especially
important for underground work-
ing. As such, geology is a vital
factor in the correct selection of
mining method and equipment.
Once a mining method is chosen,
a major variance in the geology
may make it difficult to change
the approach to mining, com-
pared to more flexible opencast
work. This chapter reviews some
of the important basic aspects of
geology that may affect decisions
about mining method. Atlas
Copco offers a full range of drill-
ing products for site investiga-
tion, and for mine development
and production. 1. Recent alluvium, lake and
sea-bed deposits e.g.
mud, sands, calcite.
2. Orebodies, e.g. containing
galena, sphalerite,
chalcopyrite and pyrite.
3. Weathered shale, per-
haps forming bauxite.
4. Weathered sandstone, perhaps
having high quartz content.
5. Weathered orebodies producing
azurite, malachite, cuprite, etc.
6. River valley deposits may inclu-
de gold, platinum, diamonds,
cassiterite or magnetite, as
well as clays and sands.
7. Volcanic rocks – fine-grained
minerals including feldspar,
quartz, olivine, hornblende,
magnetite and mica.
8. Metamorphic sandstone
– high proportion of quartz.
9. Metamorphic limestone as
marble,etc–calciteanddolomite.
10. Metamorphic shales as
slates, schists, etc. – with
garnet, mica, feldspar.
11. Contact zones between
igneous and ‘country’ rocks –
garnet, hornblende, sulphides.

Geology for Mining
to mine or tunnel through them, or both.
Some of these important characteris-
tics, which are also important for cor-
rect mineral identification in the field
before chemical analysis, are hardness,
density, colour, streak, lustre, fracture,
cleavage and crystalline form.
The particle size, and the extent to
which the mineral is hydrated or other-
wise mixed with water, can be very im-
portant to the behaviour of the rock
structure when excavated. Mineral hard-
ness is commonly graded according to
the Moh 10-point scale
The density of light-coloured miner-
als is usually below 3. Exceptions are
barite or heavy spar (barium sulphate
– BaSO4 – density 4.5), scheelite (cal-
cium tungstate – CaWO4 – density 6.0)
and cerussite (lead carbonate – PbCO4
– density 6.5). Dark coloured miner-
als with some iron and silicate have
densities between 3 and 4. Metallic ore
minerals have densities over 4 Gold has
a very high density of 19.3. Minerals
with tungsten, osmium and iridium are
normally even denser.
Streak is the colour of the mineral
powder produced when a mineral is
scratched or rubbed against unglazed
white porcelain, and may be different
from the colour of the mineral mass.
Fracture is the surface characteristic
produced by breaking of a piece of the
mineral, but not following a crystal-
lographically defined plane. Fracture
is usually uneven in one direction or
another.
Cleavage denotes the properties of
a crystal whereby it allows itself to be
split along flat surfaces parallel with
certain formed, or otherwise crystal-
lographically defined, surfaces. Both
fracture and cleavage can be important
to the structure of rocks containing sub-
stantial amounts of the minerals con-
cerned.
Proper ties
Rocks, normally comprising a mixture
of minerals, not only combine the prop-
erties of these minerals, but also exhibit
properties resulting from the way in
which the rocks have been formed, or
perhaps subsequently altered by heat,
pressure and other forces in the earth’s
crust. It is comparatively rare to find
rocks forming a homogeneous mass,
and they can exhibit hard-to-predict
discontinuities such as faults, perhaps
filled with crushed material, and major
jointing and bedding unconformities.
These discontinuities can be important
in mining, not only for the structural
security of the mine and gaining access
to mineral deposits, but also as paths
for fluids in the earth’s crust which
cause mineral concentrations. In order
for mining to be economic, the required
minerals have to be present in sufficient
concentration to be worth extracting,
and within rock structures that can be
excavated safely and economically. As
regards mine development and produc-
tion employing drilling, there must be a
correct appraisal of the rock concerned.
This will affect forecast drill penetra-
tion rate, hole quality, and drill steel
costs, as examples.
One must distinguish between micro-
scopic and macroscopic properties, to
determine overall rock characteristics.
As a rock is composed of grains of vari-
ous minerals, the microscopic proper-
ties include mineral composition, grain
size, the form and distribution of the
grain, and whether the grains are loose
or cemented together. Collectively, these
factors develop important properties of
the rock, such as hardness, abrasiveness,
compressive strength and density. In
turn, these rock properties determine the
penetration rate that can be achieved,
and how heavy the tool wear will be.
In some circumstances, certain min-
eral characteristics will be particularly
important to the means of excavation.
Moh’s hardness Typical mineral Identification of hardness
scale
1 Talc Easily scratched with a fingernail
2 Gypsum Barely scratched with a fingernail
3 Calcite Very easily scratched with a knife
4 Fluorite Easily scratched with a knife
5 Apatite Can be scratched with a knife
6 Orthoclase Difficult to scratch with a knife, but
can be scratched with quartz
7 Quartz Scratches glass and can be
scratched with a hardened steel file
8 Topaz Scratches glass and can be
scratched with emery board/paper
(carbide)
9 Corundum Scratches glass. Can be scratched
with a diamond
10 Diamond Scratches glass and can only be
marked by itself
Amphibolite.
Samples of common rock types
Dolomitic limestone.

Geology for Mining
Many salts, for example, are particu-
larly elastic, and can absorb the shocks
of blasting without a second free face
being cut, thereby directly influencing
mining method.
The drillability of a rock depends on,
among other things, the hardness of its
constituent minerals, and on the grain
size and crystal form, if any.
Quartz is one of the commonest mi-
nerals in rocks. Since quartz is a very
hard material, high quartz content in
rock can make it very hard to drill, and
will certainly cause heavy wear, par-
ticularly on drill bits. This is known as
abrasion. Conversely, a rock with a high
content of calcite can be comparatively
easy to drill, and cause little wear on
drill bits. As regards crystal form, min-
erals with high symmetry, such as cubic
galena, are easier to drill than minerals
with low symmetry, such as amphiboles
and pyroxenes.
A coarse-grained structure is easier
to drill, and causes less wear of the drill
string than a fine-grained structure. Con-
sequently, rocks with essentially the
same mineral content may be very dif-
ferent in terms of drillability. For
example, quartzite can be fine-grained
(0.5-1.0 mm) or dense (grain size 0.05
mm). A granite may be coarse-grained
(size 5 mm), medium-grained (1-5
mm) or fine-grained (0.5-1.0 mm).
A rock can also be classified in terms
of its structure. If the mineral grains are
mixed in a homogeneous mass, the rock
is termed massive, as with most granite.
In mixed rocks, the grains tend to be
segregated in layers, whether due to
sedimentary formation or metamorphic
action from heat and/or pressure. Thus,
the origin of a rock is also important,
although rocks of different origin may
have similar structural properties such
as layering. The three classes of rock
origin are:
Igneous or magmatic: formed from
solidified lava at or near the surface, or
magma underground.
Sedimentary: formed by the deposi-
tion of reduced material from other
rocks and organic remains, or by chemi-
cal precipitation from salts, or similar.
Metamorphic: formed by the trans-
formation of igneous or sedimentary
rocks, in most cases by an increase in
pressure and heat.
Igneous rocks
Igneous rocks are formed when mag-
ma solidifies, whether plutonic rock,
deep in the earth’s crust as it rises to
the surface in dykes cutting across other
rock or sills following bedding planes,
or volcanic, as lava or ash on the sur-
face. The most important mineral con-
stituents are quartz and silicates of vari-
ous types, but mainly feldspars. Plutonic
rocks solidify slowly, and are therefore
coarse-grained, whilst volcanic rocks
solidify comparatively quickly and
become fine-grained, sometimes even
forming glass.
Depending on where the magma soli-
difies, the rock is given different names,
even if its chemical composition is the
same, as shown in the table of main
igneous rock types. A further subdivi-
sion of rock types depends on the silica
content, with rocks of high silica con-
tent being termed acidic, and those with
lower amounts of silica termed basic.
The proportion of silica content can
determine the behaviour of the magma
and lava, and hence the structures it can
produce.
Sedimentary rocks
Sedimentary rocks are formed by the
deposition of material, by mechanical
or chemical action, and its consolidation
under the pressure of overburden. This
generally increases the hardness of the
rock with age, depending on its mineral
composition. Most commonly, sedimen-
tary rocks are formed by mechanical
action such as weathering or abrasion
on a rock mass, its transportation by a
medium such as flowing water or air,
and subsequent deposition, usually in
still water. Thus, the original rock will
partially determine the characteristics
of the sedimentary rock. Weathering or
erosion may proceed at different rates,
as will the transportation, affected by
the climate at the time and the nature
of the original rock. These will also
affect the nature of the rock eventually
formed, as will the conditions of deposi-
tion. Special cases of sedimentary rock
include those formed by chemical depo-
sition, such as salts and limestones, and
organic material such as coral and shell
Table of main igneous rock types
Silica (SiO2) Plutonic rocks Dykes and Sills Volcanic (mainly
content lava)
Basic – 52% Gabbro Diabase Basalt
SiO2
Intermediate Diorite Porphyrite Andesite
– 52-65%
SiO2 Syenite Syenite Trachyte porphyry
Acidic – 65% Quartz diorite Quartz porphyrite Dacite
SiO2
Granodiorite Granodiorite Rhyodacite
porphyry
Granite Quartz porphyry Rhyolite
Sandstone.
Gneiss.

Geology for Mining
limestones and coals, while others will
be a combination, such as tar sands and
oil shales.
Another set of special cases is gla-
cial deposits, in which deposition is
generally haphazard, depending on ice
movements.
Several distinct layers can often be
observed in a sedimentary formation,
although these may be uneven, accord-
ing to the conditions of deposition. The
layers can be tilted and folded by subse-
quent ground movements. Sedimentary
rocks make up a very heterogeneous
family, with widely varying character-
istics, as shown in the table of sedimen-
tary rock types.
Metamorphic rocks
The effects of chemical action, increased
pressure due to ground movement, and/
or temperature of a rock formation can
sometimes be sufficiently great to cause
a transformation in the internal struc-
ture and/or mineral composition of
the original rock. This is called meta-
morphism. For example, pressure and
temperature may increase under the
influence of up-welling magma, or be-
cause the strata have sunk deeper into
the earth’s crust. This will result in
the recrystallization of the minerals,
or the formation of new minerals. A
characteristic of metamorphic rocks is
that they are formed without complete
remelting, or else they would be termed
igneous. The metamorphic action often
makes the rocks harder and denser, and
more difficult to drill. However, many
metamorphic zones, particularly formed
in the contact zones adjacent to igneous
intrusions, are important sources of
valuable minerals, such as those con-
centrated by deposition from hydrother-
mal solutions in veins.
As metamorphism is a secondary pro-
cess, it may not be clear whether a sedi-
mentary rock has, for example, become
metamorphic, depending on the degree
of extra pressure and temperature to
which it has been subjected. The min-
eral composition and structure would
probably give the best clue.
Due to the nature of their formation,
metamorphic zones will probably be
associated with increased faulting and
structural disorder, making the plan-
ning of mine development, and efficient
drilling, more difficult.
Rock structures and mining
method
Macroscopic rock properties include
slatiness, fissuring, contact zones, lay-
ering, veining and inclination. These
factors are often of great significance in
drilling. For example, cracks or inclined
and layered formations can cause hole
deviation, particularly in long holes, and
have a tendency to cause drilling tools
to get stuck, although modern drilling
control methods can greatly reduce this
problem. Soft or crumbly rocks make it
difficult to achieve good hole quality,
since the walls can cave in. In extreme
cases, flushing air or fluid will disap-
pear into cracks in the rock, without
removing cuttings from the hole. In
some rocks there may be substantial
cavities, such as with solution passages
in limestones, or gas bubbles in igne-
ous rock. These may necessitate prior
grouting to achieve reasonable drilling
properties.
On a larger scale, the rock structure
may determine the mining method, ba-
sed on factors such as the shape of the
mineral deposit, and qualities such as
friability, blockiness, in-situ stress, and
plasticity. The shape of the mineral
deposit will decide how it should be
developed, as shown in the chapters on
mining flat and steep orebodies later in
this issue. The remaining rock qualities
can all be major factors in determining
the feasibility of exploiting a mineral
deposit, mainly because of their effect
on the degree of support required, for
both production level drives and for
development tunnels.
Mineral deposit
exploration
There will be a delicate economic ba-
lance between an investment in devel-
opment drives in stable ground, perhaps
without useful mineralization, and
Some sedimentary rock types
Rock Original material
Conglomerate Gravel, stones and boulders, generally with
limestone or quartzitic cement
Greywacke Clay and gravel
Sandstone Sand
Clay Fine-grained argillaceous material and
precipitated aluminates
Limestone Precipitated calcium carbonate, corals,
shellfish
Coals Vegetation in swamp conditions
Rock salt, potash, gypsum, etc Chemicals in solution precipitated out by
heat
Loess Wind-blown clay and sand
Typical metamorphic rocks
Rock type Original rock Degree of metamorphism
Amphibolite Basalt, diabase, gabbro High
Mica schist Mudstone, greywacke, etc Medium to high
Gneiss Various igneous rocks High
Green-schist Basalt, diabase, gabbro Low
Quartzite Sandstone Medium to high
Leptite Dacite Medium
Slate Shale Low
Veined gneiss Silicic-acid-rich silicate rocks High
Marble Limestone Low

Geology for Mining
drives within the mineral deposit, per-
haps of shorter life, but requiring more
support measures. Setting aside sup-
port requirements, in general terms it
would seem beneficial to carry out as
much of the development work as pos-
sible within the mineral deposit, ma-
king development drives in non-pro-
ductive gangue rocks as short as pos-
sible. However, it may be decided that a
major development asset, such as a shaft
or transport level, should be in as stable
a ground area that can be found, with
further drives or levels made from it.
In extreme cases, it may be found
that the mineral deposit cannot support
development workings without consid-
erable expense. In these circumstances,
it might be better to make development
drives near and below the mineral de-
posit, and exploit it with little direct en-
try, such as by longhole drilling and
blasting, with the ore being drawn off
from below.
Depending on the amount of distur-
bance that the mineral-bearing strata
has been subjected to, the mineral de-
posit can vary in shape from stratified
rock at various inclinations, to highly
contorted and irregular vein formations
requiring a very irregular development
pattern.
The latter may require small drives
to exploit valuable minerals, although
the productivity of modern mining
equipment makes larger section drives
more economic, despite the excavation
of more waste rock.
The tendency of a rock to fracture,
sometimes unpredictably, is also im-
portant to determine drivage factors,
such as support requirements, and the
charging of peripheral holes to prevent
overbreak. Although overbreak may not
be so important in mining as in civil
tunnelling, it can still be a safety con-
sideration to prevent the excavation of
too much gangue material, and to pre-
serve the structure of a drive.
Investigation and
exploration
It is clear that rock structures, and the
minerals they contain, can result in a
wide variety of possible mining strate-
gies. Obviously, the more information
that is gained, the better should be the
chances of mining success. There are
plenty of potential risks in underground
mining, and it is best to minimize these.
Using modern mining equipment,
there is the potential to turn the mine
into a mineral factory. However, if un-
certainties manifest themselves in un-
foreseen ground conditions, disap-
pearing orebodies, and factors such as
excessive water infiltration, then the
advantage of productive mining equip-
ment will be lost, as it is forced to stand
idle.
The only way to avoid these situa-
tions is to carry out as much exploration
work as possible, not only to investigate
the existence and location of worthwhile
minerals, but also to check on rock qua-
lities in and around the deposit. In un-
derground mining, information from
surface borehole and geophysical me-
thods of investigation can be supple-
mented by probe or core drilling under-
ground. The resulting vast amount of
data may be too much to be assessed
manually, but computer software pro-
grams are available to deduce the best
strategies for mineral deposit exploi-
tation. In addition, the mining exper-
tise of Atlas Copco is available to help
mining engineers decide, not only on
the best equipment to use for investi-
gation, development and production, but
also how these can be used to maximum
effect.
The value of the mineral to be mined
will obviously be a determinant on how
much investigation work is desirable,
but there will be a minimum level for
each type of mine, in order to give some
assurance of success.
For example, lowvalue stratified de-
posits, which are known to be fairly
uniform in thickness and have regular
dips, may not necessitate many bore-
holes, although there could still be
surprises from sedimentary washouts
or faults. On the other hand, gold de-
posits in contorted rock formations will
require frequent boreholes from under-
ground, as well as from the surface, to
give assurance of the location of the
deposit and to sample the minerals it
contains.
Rock classification for
drilling
Having determined the value and shape
of a mineral deposit, the nature and
structure of the rocks that surround it,
and the likely strategy for the mine deve-
lopment, it should be possible to deter-
mine the suitability of various excava-
tion methods for the rocks likely to be
encountered.
It will also be necessary to deter-
mine which ancillary equipment may
be required, and how best to fit this into
the excavation cycle.
With drill-and-blast development
drivages, for example, the rock types
and structure may determine that sub-
stantial support is required. This, in
Diabase.
Granite.

Geology for Mining
turn, may require a rockbolting facility
on the drill rig, perhaps with an access
basket suitable for erecting arch crowns
and charging blastholes. It may be de-
cided that an additional rockbolting rig
is required, for secondary support.
In order to systematically determine
the likely excavation and support re-
quirements, the amount of consumables
required, and whether a particular me-
thod is suitable, a number of rock clas-
sification systems have been developed.
These are generally oriented to a par-
ticular purpose, such as the level of sup-
port required or the rock’s drillability.
The methods developed to assess dril-
lability are aimed at predicting produc-
tivity and tool wear. Factors of drillabil-
ity include the likely tool penetration
rate commensurate with tool wear, the
stand-up qualities of the hole, its straight-
ness, and any tendency to tool jamming.
Tool wear is often proportional to drill-
ability, although the rock’s abrasiveness
is important.
Rock drillability is determined by se-
veral factors, led by mineral composi-
tion, grain size and brittleness. In crude
terms, rock compressive strength or
hardness can be related to drillability
for rough calculations, but the matter is
usually more complicated.
The Norwegian Technical University
has determined more sophisticated
methods: the Drilling Rate Index (DRI)
and the Bit Wear Index (BWI).
The DRI describes how fast a par-
ticular drill steel can penetrate. It also
includes measurements of brittleness
and drilling with a small, standard ro-
tating bit into a sample of the rock. The
higher the DRI, the higher the penetra-
tion rate, and this can vary greatly from
one rock type to another, as shown in
the bar chart.
It should be noted that modern drill
bits greatly improve the possible pene-
tration rates in the same rock types.
Also, there are different types of bits
available to suit certain types of rock.
For example, Secoroc special bits for
soft formations, bits with larger gauge
buttons for abrasive formations, and
guide bits or retrac bits for formations
where hole deviation is a problem.
The BWI gives an indication of
how fast the bit wears down, as deter-
mined by an abrasion test. The higher
the BWI, the faster will be the wear.
In most cases, the DWI and BWI are
inversely proportional to one another.
However, the presence of hard min-
erals may produce heavy wear on the bit,
despite relatively good drillability. This
is particularly the case with quartz,
which has been shown to increase wear
rates greatly. Certain sulphides in
orebodies are also comparatively hard,
impairing drillability.
Other means of commonly used rock
classification include the Q-system
(Barton et al, through the Norwegian
Geotechnical Institute), Rock Mass
Rating RMR (Bieniawski), and the
Geological Strength Index GSI (Hoek
et al). Bieniawski’s RMR incorporates
the earlier Rock Quality Designation
(RQD – Deere et al), with some impor-
tant improvements taking into account
additional rock properties.
All give valuable guidance on the
rock’s ease of excavation, and its self-
supporting properties. In most cases,
engineers will employ more than one
means of rock classification to give a
better understanding of its behaviour,
and to compare results.
Björn Samuelsson
Relationship between drilling rate index and various rock types.
Marble Limestone

Mineral Prospecting and Exploration
Prospecting
Prospecting involves searching a district
for minerals with a view to further ope-
ration. Exploration, while it sounds si-
milar to prospecting, is the term used
for systematic examination of a deposit.
It is not easy to define the point where
prospecting turns into exploration.
A geologist prospecting a district is
looking for surface exposure of miner-
als, by observing irregularities in co-
lour, shape or rock composition. He uses
a hammer, a magnifying glass and some
other simple instruments to examine
whatever seems to be of interest. His
experience tells him where to look, to
have the greatest chances of success.
Sometimes he will stumble across an-
cient, shallow mine workings, which
may be what led him to prospect that
particular area in the first place.
Soil-covered ground is inaccessible
to the prospector, whose first check
would be to look for an outcrop of the
mineralization. Where the ground cover
comprises a shallow layer of alluviums,
trenches can be dug across the miner-
alized area to expose the bedrock. A
prospector will identify the discovery,
measure both width and length, and
calculate the mineralized area. Rock
samples from trenches are sent to the
laboratory for analysis. Even when mi-
nerals show on surface, determining any
extension in depth is a matter of quali-
fied guesswork. If the prospector's
findings, and his theorizing about the
probable existence of an orebody are
solid, the next step would be to explore
the surrounding ground. Exploration
is a term embracing geophysics, geo-
chemistry, and also drilling into the
ground for obtaining samples from any
depth.
Geophysical exploration
From surface, different geophysical me-
thods are used to explore subsurface for-
mations, based on the physical proper-
ties of rock and metal bearing minerals
such as magnetism, gravity, electrical
Gold panning in the wind.
Mineral prospecting and
exploration
Finding orebodies
For a geologist in the mining busi-
ness, exploiting an orebody is the
easy part of the job. The hardest
part is to find the orebody and de-
fine it. But how do you find these
accumulations of metallic miner-
als in the earth's crust? The mining
company has to ensure that an ore-
body is economically viable, and
needs a guarantee of ore produc-
tion over a very long period of time,
before it will engage in the heavy
investment required to set up a
mining operation. Even after pro-
duction starts, it is necessary to
locate and delineate any exten-
sions to the mineralization, and
to look for new prospects that
may replace the reserves being
mined. Investigating extensions,
and searching for new orebodies,
are vital activities for the mining
company.

conductivity, radioactivity, and sound
velocity. Two or more geophysical meth-
ods are often combined in one survey,
to acquire more reliable data. Results
from the surveys are compiled, and
matched with geological information
from surface and records from any core
drilling, to decide if it is worth proceed-
ing with further exploration.
Surveys
Magnetic surveys measure variations
in the Earth's magnetic field caused by
magnetic properties of subsurface rock
formations. In prospecting for metallic
minerals, these techniques are parti-
cularly useful for locating magnetite,
pyrrhotite and ilmenite. Electromagnetic
surveys are based on variations of elec-
tric conductivity in the rock mass. An
electric conductor is used to create a
primary alternating electromagnetic
field. Induced currents produce a sec-
ondary field in the rock mass. The res-
ultant field can be traced and measu-
red, thus revealing the conductivity
of the underground masses. Electromag-
netic surveys are mainly used to map
geological structures, and to discover
mineral deposits such as sulphides
containing copper or lead, magnetite,
pyrite, graphite, and certain manganese
minerals.
Electric surveys measure either the
natural flow of electricity in the gro-
und, or galvanic currents led into the
ground and accurately controlled.
Electrical surveys are used to locate
mineral deposits at shallow depth and
map geological structures to determine
the depth of overburden to bedrock, or
to locate the groundwater table.
Gravimetric surveys measure small
variations in the gravitational field cau-
sed by the pull of underlying rock mas-
ses. The variation in gravity may be
caused by faults, anticlines, and salt
domes that are often associated with
oil-bearing formations.
Gravimetric surveys are also used
to detect high-density minerals, like
iron ore, pyrites and lead-zinc miner-
alizations.
In regions where rock formations con-
tain radioactive minerals, the intensity
of radiation will be considerably higher
than the normal background level. Mea-
suring radiation levels helps locate de-
posits containing uranium, thorium and
other minerals associated with radioac-
tive substances.
The seismic survey is based on varia-
tions of sound velocity experienced in
different geological strata. The time is
measured for sound to travel from a
source on surface, through the underly-
ing layers, and up again to one or more
detectors placed at some distance on
surface. The source of sound might be
the blow of a sledgehammer, a heavy
falling weight, a mechanical vibrator,
or an explosive charge. Seismic surveys
determine the quality of bedrock, and
can locate the contact surface of geo-
logical layers, or of a compact mineral
deposit deep in the ground. Seismic sur-
veys are also used to locate oil-bearing
strata.
Geochemical surveying is another ex-
ploration technology featuring several
Two computer generated views of Agnico Eagle's Suurikuusiko gold mining project
showing both surface and underground mining.
Is there gold in the trench?
International Gold Exploration AB, IGE conducts
exploration works in Kenya.

specialities, the main one being to de-
tect the presence of metals in the top-
soil cover. By taking a large number of
samples over an extended area and
analyzing the minute contents of each
metal, regions of interest are identi-
fied. The area is then selected for more
detailed studies.
Exploratory drilling
For a driller, all other exploration me-
thods are like beating about the bush.
Drilling penetrates deep into the ground,
and brings up samples of whatever it
finds on its way. If there is any miner-
alization at given points far beneath the
surface, drilling can give a straight-
forward answer, and can quantify its
presence at that particular point.
There are two main methods of ex-
ploratory drilling. The most common,
core drilling, yields a solid cylinder
shaped sample of the ground at an
exact depth. Percussion drilling yields
a crushed sample, comprising cuttings
from a fairly well-determined depth
in the hole. Beyond that, the drillhole
itself can provide a complementary
amount of information, particularly by
logging using devices to detect physical
anomalies, similar to the geophysical
surveys mentioned above.
Core drilling is also used to define
the size and the exact borders of minera-
lization during the lifetime of the mine.
This is important for determining ore
grades being handled, and vital for cal-
culating the mineral reserves that will
keep the mine running in the future. A
strategically-placed underground core
drill may also probe for new ore bodies
in the neighbourhood.
Core drilling
In 1863, the Swiss engineer M Lescot
designed a tube with a diamond set face,
for drilling in the Mount Cenis tunnel,
where the rock was too hard for conven-
tional tools. The intention was to explore
rock quality ahead of the tunnel face,
and warn miners of possible rock falls.
This was the accidental birth of core
drilling, a technique now very widely
used within the mining industry. Core
drilling is carried out with special drill
rigs, using a hollow drill string with an
impregnated diamond cutting bit to re-
sist wear while drilling hard rock. The
crown-shaped diamond bit cuts a
cylindrical core of the rock, which is
caught and retained in a double tube
core-barrel.
A core-catcher is embedded in, or
just above, the diamond bit, to make
sure that the core does not fall out of the
tube. In order to retrieve the core, the
core-barrel is taken to surface, either by
pulling up the complete drill string or,
if the appropriate equipment is being
used, by pulling up only the inner tube
of the core-barrel with a special fishing
device run inside the drill string at the
end of a thin steel wire.
The core is an intact sample of the un-
derground geology, which can be exam-
ined thoroughly by the geologist to
determine the exact nature of the rock
and any mineralization. Samples of
Atlas Copco underground core drilling rig Diamec U4.

special interest are sent to a laboratory
for analysis to reveal any metal con-
tents. Cores from exploration drilling
are stored in special boxes and kept in
archives for a long period of time. Boxes
are marked to identify from which hole,
and at what depth, the sample was ta-
ken. The information gathered by core
drilling is important, and represents sub-
stantial capital investment.
Traditionally, core drilling was a very
arduous job, and developing new techni-
ques and more operator-friendly equip-
ment was very slow, and the cost per
drilled metre was often prohibitive. Atlas
Copco Geotechnical Drilling and Explo-
ration pioneered several techniques to
reduce manual work, increase efficiency
and cut the cost per drilled metre.
Over the years, the company developed
thin walled core barrels, diamond impreg-
nated bits, aluminium drill rods, fast
rotating hydraulic rigs, mechanical rod
handling, and, more recently, partly or
totally computer-controlled rigs. Core
drilling has always been the most power-
ful tool in mineral exploration. Now that
it has become much cheaper, faster and
easier, it is being used more widely.
Reverse circulation
drilling
To obtain information from large ore-
bodies where minerals are not concen-
trated in narrow veins, reverse circulation
drilling is used. Reverse circulation dril-
ling is a fast, but inaccurate, explora-
tion method, which uses near-standard
percussion drilling equipment. The
flushing media is introduced at the
hole collar in the annular space of a
double-tubed drill string, and pushed
down to the bottom of the hole to flush
the cuttings up through the inner tube.
The drill cuttings discharged on sur-
face are sampled to identify variations
in the mineralization of the rock mass.
Reverse circulation drilling uses much
heavier equipment than core drilling,
and has thus a limited scope in depth.
From prospecting to
mining
Every orebody has its own story, but
there is often a sequence of findings.
After a certain area catches the interest
of the geologists, because of ancient
mine works, mineral outcrops or geo-
logical similarities, a decision is taken
to prospect the area. If prospecting con-
firms the initial interest, some geophy-
sical work might be carried out. If inter-
est still persists, the next step would be
to core drill a few holes to find out if
there is any mineralization.
To quantify the mineralization, and
to define the shape and size of the ore
body, then entails large investment to
drill exploratory holes in the required
patterns.
At every step of the procedure, the
geologists examine the information at
hand, to recommend continuing the ex-
ploration effort. The objective is to be
fairly certain that the orebody is eco-
nomically viable by providing a detailed
knowledge of the geology for a clear
financial picture. Ore is an economic
concept, defined as a concentration of
minerals, which can be economically
exploited and turned into a saleable
product.
Before a mineral prospect can be
labelled as an orebody, full knowledge
is required about the mineralization,
proposed mining technology and pro-
cessing. At this stage a comprehensive
feasibility studied is undertaken cover-
ing capital requirements, returns on
investment, payback period and other
essentials, in order for the board of di-
rectors of the company to make the
final decision on developing the pros-
pect into a mine.
When probabilities come close to
certainties, a decision might be taken to
proceed with underground exploration.
This is an expensive and time-consum-
ing operation, involving sinking a shaft
or an incline, and pilot mining drifts and
galleries. Further drilling from under-
ground positions and other studies will
further establish the viability of the
orebody.
After the mineralization has been
defined in terms of quantity and quality,
the design of mine infrastructure starts.
The pictures on page 14 show recent
plans at the Suurikuusikko gold mine
project in Finland where the optimum
mining methods combine both open pit
and un-derground mining. Production
can start in the open pit while preparing
for the underground operation.
With an increasing level of geologi-
cal information the mineral resources
get better confirmed. The feasibility
study will take into consideration all
economical aspects, as well as the ef-
fects of the selected mining method.
Depending on the mining method, there
could be essential differences between
mineral resources and ore reserves, both
in terms of quantity and grade.
Hans Fernberg
Exploration Results
Mineral Resources Ore Reserves
Increasing level
of geological
knowledge and
confidence
Indicated
Inferred
Measured Proved
Probable
Consideration of mining, metallurgical, economic, marketing,
legal, environmental, social and governmental factors
(the ”modifying factors”)
The 2004 Australasian code for reporting exploration results, mineral resources and ore reserves.

Right Balance
Conventional core drilling
The technique which produces cores of
subsurface material, core drilling, is the
most commonly used method of obtain-
ing information about the presence of
minerals or precious metals, as well as
rock formations. However, reverse cir-
culation drilling (RC), which produces
samples as chips, is gaining ground.
The reason is easy to see. RC drilling
is a faster and more economical way of
pre-collaring a deep hole in order to get
down to where the orebody is located.
Once there, the driller can then decide
to continue with RC drilling to extract
chips for evaluation, or switch to dia-
mond core drilling to extract cores. In
this way, RC drilling becomes the per-
fect complement to conventional core
drilling. Selecting which method to
use for actual sampling work depends
largely on the preference of the geo-
logists, and their confidence in the
quality of the samples. Today, RC dril-
ling has become so advanced that more
Finding the right balance in
exploration drilling
Chips or cores?
The question often faced by geolo-
gists and contractors is deciding
which method of exploration dril-
ling will get the most effective and
economical results. These days, the
answer is quite likely to be a com-
bination of chip sampling and co-
ring. Three key factors have proved
decisive in the successful search
for minerals and precious metals:
time, cost and confidence. In other
words, the time required, the cost
of getting the job done, and con-
fidence in the quality of the sam-
ples brought to the surface for
analysis. This is more a question
of basic technology and logic than
one of science. But it is interest-
ing to see these three factors ex-
pressed as a mathematical for-
mula: confidence over time multi-
plied by cost, equals profit. With
profit, as always, as the driving
force.
There are pros and cons with both RC drilling and core drilling.
Substantial savings can be made by pre-collaring holes using RC drilling, once
the general location of the mineralized zone has been established.
Pre-collaring
Fast and
economical
RC drilling
without taking
samples
Mineralized zone: Chip
samples from RC and/or
cores for evaluation

Right Balance
and more geologists believe that chips
are perfectly sufficient as a means of
determining ore content. The commer-
cialization of RC drilling started in the
1980s but the technique has certainly
been around for much longer.
As early as 1887, Atlas Copco Craelius
had developed a rig that could retrieve
cores from depths of 125 m. Confidence
in these samples among geologists was
high, allowing them to evaluate a piece
of solid rock. In those days, time was
not necessarily of any great importance
and neither was cost, with inexpensive
manpower readily available.
However, the demand for such pro-
ducts quickly increased, and availability
had to keep pace. This is very much the
case today with sharp market fluctu-
ations, and so technology innovators
have to find ways to optimize profit in
all situations.
Time factor
DTH hammers were invented in 1936
and became popular during the 1970s,
mainly for water well drilling applica-
tions. However, the method proved
very useful for prospecting, affording
an initial evaluation on the spot of the
cuttings emanating from the borehole.
DTH drilling offers a considerably
higher drilling speed compared to core
drilling, and the method was further
developed to increase its performance.
Higher air pressures combined with high
availability of the hammer are two fac-
tors that make it possible to drill faster.
Durability of the bit inserts is also much
improved, allowing more metres to be
drilled without having to pull up the
drillstring, further improving efficiency
and utilization of the hammer.
The logistics surrounding the dril-
ling programme concerning availability
of parts, fuel, casing, water, and con-
sumables also have a direct influence
on the number of metres drilled per
shift.
Significant time savings can be achie-
ved by using RC and core drilling in
a balanced combination (see table 1).
Here we can see that one RC rig can be
used to drill enough pre-collars to keep
three core drilling rigs running for 24
h/day. The time factors show obvious
benefits using a combination of the two
methods. In this scenario, a minimum
of 25% of the total metres drilled were
specified as core drilling.
Cost factor
The cost perspective does not have
any negative surprises in store as the
costs are mostly related to the time fac-
tor. The investment in RC rigs and equip-
ment is higher compared to those of
core drilling, but as shown in table 2,
the costs are reduced when a combina-
tion of the two methods is used.
In this example, it is shown that both
time and costs favour RC drilling. The
figures are easy to evaluate. They vary
depending on the location and the local
conditions, but the relativity remains
the same, and is strongly reflected in
the development of the exploration
drilling process.
To further shorten time and cost, im-
mediate results from on-site evaluation
can be used, for which a scanning pro-
cess is already available.
However, in the future it may not be
necessary to drill to obtain sufficient
information about the orebodies, and
manufacturers such as Atlas Copco
Craelius are already taking up the chal-
lenge to develop equipment and tech-
nologies with no limits and low envi-
ronmental impact.
Confidence factor
The third variable in the equation is
the confidence factor, because investors
and geologists place strict demands on
contractors to deliver the highest qual-
ity geological information. Investors
always require a fast return on their in-
vestments, and the geologists need solid
results for the mine planners. However,
whenever a gold nugget is found, the
Scenario 1
girgnillirderoc1htiwsruoh42/erocm07gnillirderoc%001
457 days
Scenario 2
50% RC (pre-collars only), 50% core drilling 70m core / 24 hours with 1 core drilling rig
301 days
Scenario 3
75% RC (pre-collars full holes), 25% core drilling 70m core / 24 hours with 1 core drilling rig
223 days
In case three core drilling rigs would have been available in scenario 1, expected time is
152 days compared with 457 days.
In case three core drilling rigs would have been available in scenario 2, expected time is
149 days compared with 301 days.
A rough conclusion gives that the RC rig is somewhat faster than 3 core drilling rigs together.
457 days 2,580,000 USD
301 day
223 day
Principles for RC drilling showing flow of
compressed air and chips. The sampling
collection box is integrated into the cyclone.
Table 1.
Table 2.
740,000 USD
320,000 USD
Approx. cost of RC drilling – 30 USD / metre
Approx. cost of core drilling – 80 USD / metre

Right Balance
exploration drilling will not be carried
out by the same people, so reliability of
information is critical. There are many
reasons why geologists should choose
their drilling method carefully.
If there is no need for continuous in-
formation about the geological forma-
tion on the way down, there is no need
for samples. It is just a matter of mini-
mizing the drilling time. The geometry
of the orebody is already known, and
just a reconfirmation of the boundaries
is necessary. In this case, RC drilling is
an efficient method to use.
A first scanning of virgin territory
is being done where the goal is just to
obtain a preliminary indication of pos-
sible content. In this case, the geologist
is not relying on any mineralized struc-
ture or geometry. With an evaluation
giving positive results, a programme of
core drilling is the logical way to con-
tinue in order to bring the project to a
resource/reserve status.If the minera-
lized structure is identified but the
geometry and rate of content varies,
RC drilling is used as an indicator for
ensuring continued grade control.
The geologist wants dry and repre-
sentative samples in order to make opti-
mal evaluations. RC drilling below the
groundwater table was previously be-
lieved to undermine sample quality.
Core drilling therefore remained the
only viable method for these depths
Today, the availability of high pressure
compressors and hammer tools makes
it possible for RC drilling to reduce
costs even for these depths.
These days, professional contractors
deliver dry sampling down to depths
of 500 m. By sealing off the bit from
the rest of the hole it can be kept dry.
A correct selection of shroud vs bit tol-
erance maintains a pressurized zone
around the bit. Boosted air pressure is
needed to meet the higher water pres-
sure on its way down the hole. In addi-
tion, a dry bit drills faster.
It must be remembered that infor-
mation from a core is crucial in esti-
mating the period of mineralized struc-
tures. The core helps the geologist to
calculate the cost of extracting the
mineral from the ore. Large volumes of
rock have to be excavated to obtain just
a few grammes of a valuable mineral.
Cores also yield geotechnical data.
Data about slope stability can be of the
highest importance. Ground conditions
are naturally also of great importance
and may produce questionable sam-
ples if some of the information from
fissured zones is left behind in the
hole and not collected. In such circum-
stances, core drilling could be the only
alternative.
Increased usage of
RC drilling
RC drilling is on the increase, and may
well account for 55% of all metres
drilled in 2008. The diagram above
shows some estimated ratios between
core and RC drilling in different parts
of the world in 2002. In terms of metres
drilled, RC accounts for 50% and core
drilling for 50%. Tradition and environ-
mental impact play large roles. RC rigs
are heavy, and are mounted on trucks
or track carriers. This fact tends to
favour core drilling rigs, which are much
lighter and more adaptable in order
to be flown into remote and sensitive
environments.
In areas with extremely cold climates
and where permafrost is present, RC
drilling may have its limitations. Anti-
freeze rock drill oil can help to keep
the hammer and bottom of the hole free
from ice. Other purely practical issues
determine the choice of one or the other
drilling method.
An intelligent, balanced choice be-
tween the two methods is the key to
optimal results. The geologist plays an
extremely important role in finding this
balance, as do the manufacturers such
as Atlas Copco Geotechnical Drilling
and Exploration, who continue to pro-
vide the right tools for the job.
Jan Jönsson
Ratios between core and RC drilling. The figures reflect total exploration expenditures from national statistics for surface and underground.
0
20
40
60
80
100
Canada latin
america
russia
China
australia Se asia uSa africa
rC drilling
Core drilling
%
Explorac 220RC.

Superior Productivity
in Exploration Drilling
www.atlascopco.com
In these busy times for exploration drillers, the focus is on
superior productivity at lower cost.
Through innovative products, local presence and technical
support, Atlas Copco delivers the most competitive solutions
for diamond core drilling and reverse circulation.
On surface or underground, from Arctic regions to sunburnt
deserts - you can count on the most comprehensive range of
exploration drilling equipment wherever you are.

Mine Infrastructure
Underground infrastructure
Mining methods used underground are
adapted to the rock conditions, and the
shape, dimensions, strength and stabil-
ity of the orebody. In order to work the
underground rock mass, infrastructure
is required for access to work places, ore
production, power supply, transport of
ore, ventilation, drainage and pumping
as well as maintenance of equipment.
Traditionally, the most common me-
thod to transport men, material, ore and
waste is via vertical shafts. The shaft
forms the access to the various main un-
derground levels, and is the mine’s main
artery for anything going up or down.
Shaft stations, drifts and ramps connect
stopes with orepasses, tramming levels,
and workshops for movement of miners
and equipment.
Efficient ore handling is important.
The blasted ore is loaded from produc-
tion stopes, via orepasses to a main hau-
lage level, commonly railbound, and
thence to the crusher at the hoisting
shaft.
The crushed ore is then stored in a
silo before transfer by conveyor to the
measuring pocket at the skip station,
from where it is hoisted to the surface
stockpile. To decide on the shaft bottom
and main haulage level elevations are
crucial, as these are permanent instal-
lations offering little or no flexibility in
the event that mining progresses below
these levels. Consequently extensive
exploration drilling has to be conducted
to identify sufficient ore reserves above
the main haulage level before final de-
sign of the permanent installations can
progress.
There is currently a strong tendency to
avoid shaft sinking by extending ramps
from the surface successively deeper, to
depths exceeding 1,000 m. There are a
number of locations where the deeper
ore is hauled by trucks up ramps to an
existing railbound haulage system to
the main crusher, from where it can be
hoisted to the surface.
Services
Electric power is distributed throughout
the mine, and is used to illuminate work
Ramp access for transport and haulage.
Underground mining infrastructure
Maximizing
recovery
The underground mine aims for
maximum economic recovery of
minerals contained in the bed-
rock. The orebody is the recove-
red volume containing valuable
minerals, taking ore losses and
dilution into account. The amount
of ore losses in pillars and rem-
nants, and the effects of waste
dilution, will largely depend on
the mining method to be applied.
Waste dilutes the ore, so miners
try to leave it in place, wherever
possible, especially when expen-
sive mineral dressing methods
are applied. Flotation of sulphide
ore is more expensive than mag-
netic separation of iron ore. Ore
close to the surface is mined by
open pit techniques, in which the
waste rock can be separated by
selective blasting and loading,
and trucked to the waste dump
instead of entering and diluting
the ore flow into the concentra-
tor. Subsurface orebodies are ex-
ploited by underground mining,
for which techniques are more
complex. A combination of open
pit mining and preparation for
future underground mining is
commonly used.

Mine Infrastructure
places and to power drill rigs, pumps
and other machines. A compressor plant
supplies air to pneumatic rock drills and
other tools, through a network of pipes.
Water reticulation is necessary in the
mine, wherever drilling, blasting and
mucking takes place, for dust suppres-
sion and hole flushing. Both ground
water and flushing water are collected
in drains, which gravitate to settling
dams and a pump station equipped with
high-lift pumps to surface.
Air quality in mine workings must
be maintained at an acceptable health
standard. The mine needs a ventilation
system, to remove smoke from blasting
and exhaust gases from diesel-powered
machines, and to provide fresh air for
the workers. This is normally provided
via downcast fresh-air shafts. High-
pressure fans on surface extract exhaust
air through the upcast shafts. Ventilation
doors control the underground airflow,
passing fresh air through active work
areas. Polluted air is collected in a sy-
stem of exhaust airways for channelling
back to the upcast shafts. As most of the
infrastructure is located on the footwall
side of the orebody, the fresh air is
normally channelled via the footwall
towards the hangingwall, from where
the exhaust air is routed to the surface.
Transport infrastructure
Each mining method requires a differ-
ent underground infrastructure, such
as access drifts to sublevels, drifts for
longhole drilling, loading drawpoints,
and orepasses. Together, they form an
intricate network of openings, drifts,
ramps, shafts and raises, each with its
designated function.
The shaft is a long-lived installation,
and may be more than 50 years old. The
hoist and cage provide access to the shaft
station, which connects with a main level
along which trains or conveyors may
run. The skip is the most efficient way to
hoist ore from underground to surface.
Materials handling may be by utility
vehicles or locomotive-hauled trains.
The co-ordination of train haulage with
shaft hoisting, from level to level, makes
the logistics of rail transport complex.
Workers in a rail-track mine are requi-
red to wait for cage riding until shift
changes, or scheduled hours, with ma-
terial transport only permitted at certain
periods. Ore hoisting takes priority over
manriding and material transport.
The Load Haul Dump (LHD) loader
introduced mines to diesel power and
rubber-tyred equipment in the 1970s.
This was the birth of trackless mining,
a new era in which labour was replaced
by mobile equipment throughout the
mine. Maintenance workshops are now
located underground at convenient
points, usually on main levels between
ramp positions.
The shaft remains the mine’s main
artery, and downward development is by
ramps to allow access for the machines.
On newer mines, as mentioned above, a
decline ramp from surface may facili-
tate machine movements and transport
of men and materials, and may also
be used for ore transportation by truck
or conveyor, eliminating the need for
hoisting shafts.
Ramps and shafts
Mine development involves rock excava-
tion of vertical shafts, horizontal drifts,
inclined ramps, steep raises, crusher sta-
tions, explosives magazines, fuel stores,
Settling
pond
Headframe
Production
plant
Tailings
Skip
Skip
Water basin
Pump station
Conveyor belt
Ore
bin
Skip filling
station
SumpMeasuring
pocket
Ventilation
shaft
Decline
Open pit
(mined out)
Producing
stopes
Development
of stopes
Mined out
and
backfilled
Abandoned
level
Sublevel
Internal
ramp
Haulage level
Future reserves?
Exploration
Drilling
Main level
Ore
pass
Ore
Cage
Crusher
© Atlas Copco Rock Drills AB, 2000
Workshop,
fuelling,
storage
Basic infrastructure required for a typical underground mine.

Mine Infrastructure
pumphouses and workshops. Drill/blast
is the standard excavation method for
drifting. Firing sequence for a typical
parallel hole pattern is shown to the
right. Note that the contour holes are
fired simultaneously with light explo-
sives, and that the bottom holes, or lift-
ers, are fired last to shake up the muck
pile for faster mucking.
A deep shaft may secure many years of
production, until ore reserves above the
skip station are exhausted. The shaft can
be rectangular, circular or elliptical in
profile. Extending the shaft in an ope-
rating mine is costly and difficult, re-
quiring both expert labour and special-
ized equipment.
Drifts and ramps are dimensioned to
accommodate machines passing through,
or operating inside. Space must include
a reasonable margin for clearance, walk-
ways, ventilation ducts, and other facili-
ties. Cross-sections vary from 2.2 m x
2.5 m in mines with a low degree of
mechanization to 5.5 m x 6.0 m where
heavy equipment is used. Only 5.0 sq m
section is sufficient to operate a rail-
bound rocker shovel, whereas 25.0 sq m
may be needed for a loaded mine truck,
including ventilation duct.
Normal ramp grades vary between
1:10 and 1:7, with the steepest grade to
1:5. The common curve radius is 15.0
m. A typical ramp runs in loops, with
grade 1:7 on straight sections, reduced
to 1:10 on curves.
Raising and winzing
Raises are steeply inclined openings,
connecting the mine’s sub levels at dif-
ferent vertical elevations, used for lad-
derways, orepasses, or ventilation. In-
clination varies from 55 degrees, which
is the lowest angle for gravity transport
of blasted rock, to vertical, with cross-
sections from 0.5 to 30 sq m. When the
excavation of raises is progressing down-
wards they are called winzes.
Manual excavation of raises is a
tough and dangerous job, where the
miner climbs the raise by extending the
ladderway, installs the temporary plat-
form, and drills and charges the round
above his head. As such, manual raises
are limited to 50 m-high. However, the
efficiency can be greatly improved by
using a raise climber up to 300 m.
The drop raise technique is used for
slot raises and short orepasses, using
longhole drilling and retreat blasting
from bottom to top, see figure below.
Inverted drop raising is performed the
other way around.
Raise boring
The raise boring machine (RBM) may be
used for boring ventilation raises, ore-
passes, rock fill passes, and slot raises.
It provides safer and more efficient me-
chanized excavation of circular raises,
up to 6 m-diameter.
In conventional raise boring, a down-
ward pilot hole is drilled to the target
level, where the bit is removed and re-
placed by a reaming head. The RBM
then reams back the hole to final dia-
meter, rotating and pulling the reaming
head upward. The cuttings fall to the
lower level, and are removed by any
convenient method. An RBM can also
1
1
2 2
3
3
3
44
44
3
Firing sequence of a typical hole pattern (*contour holes).
Long hole drilling alternative to raise boring.

Mine Infrastructure
be used to excavate raises where there
is limited, or no, access to the upper le-
vel. In this boxhole boring method, the
machine is set up on the lower level, and
a full diameter raise is bored upward.
This method is used for slot hole drill-
ing in sub level caving and block caving
methods. The cuttings are carried by
gravity down the raise, and are deflected
from the machine by the use of a muck
collector and a muck chute.
An alternative method to excavate
box holes is to use longhole drilling with
extremely accurate holes to enable bla-
sting in one shot. The Simba MC 6-ITH
shown below is modified for slot dril-
ling so that the holes will closely fol-
low each other, providing sufficient open
space for consecutive blasting. The dril-
ling and blasting results are shown below.
Hole opening, or downreaming, using
a small-diameter reamer to enlarge an
existing pilot hole, can also be carried
out by an RBM.
The capital cost of an RBM is high,
but, if used methodically and consis-
tently, the return on investment is very
worthwhile. Not only will raises be
constructed safer and faster, they will
be longer, smoother, less disruptive than
blasting, and yield less overbreak. The
rock chips produced by an RBM are con-
sistent in size and easy to load.
The BorPak is a small, track-mounted
machine for upward boring of inclined
raises. It starts boring upwards through
a launching tube. Once into rock, grip-
pers hold the body, while the head ro-
tates and bores the rock fullface. BorPak
can bore blind raises with diameters from
1.2 m to 1.5 m, up to 300 m-long.
Gunnar Nord
Atlas Copco Robbins 53RH-EX raise boring machine.
Simba MC 6-ITH with slot hammer.
Sufficient expansion space is created
for production blast holes to follow.
Holes at breakthrough after 32 m.

Raise Boring
Raise boring concept
The raise boring machine (RBM) is set
up at the surface or upper level of the
two levels to be connected, and a small-
diameter pilot hole is drilled down to
the lower level using a string of drill
pipes and a tricone bit. A reamer is then
attached to the drill string at the lower
level, and the RBM provides the rota-
tional torque and pulling power to ream
back to the upper level. The cuttings
from the reamer fall to the lower level
for removal. Raise bore holes of over 6
m-diameter have been bored in medium
to soft rock, and single passes in hard
rock can be up to 1 km in length.
Advantages of raise boring are that
miners are not required to enter the ex-
cavation while it is underway, no explo-
sives are used, a smooth profile is ob-
tained, and manpower requirements are
reduced. Above all, an operation that
previously was classified as very dan-
gerous can now be routinely undertaken
as a safe and controlled activity.
Specific applications of bored raises
in mining are: transfer of material;
ventilation; personnel access; and ore
Robbins 73RH C derrick assembly layout.
Principles of raise boring
Efficiency and safety
Raise boring is the process of me-
chanically boring, drilling or ream-
ing a vertical or inclined shaft or
raise between two or more levels.
Some 40 years ago, the world’s first
modern raise boring machine was
introduced by the Robbins Com-
pany. It launched a revolution in
underground mining and construc-
tion, and the technique is now ac-
cepted as the world standard for
mechanical raise excavation. New
products from Atlas Copco, such
as the BorPak, concepts such as
automatic operation and comput-
erization, and techniques such as
horizontal reaming, are creating
exciting new opportunities in the
underground environment. Atlas
Copco Robbins supplies the com-
plete raise boring package for all
situations, together with technical
and spares backup.
Raise boring process.

Raise Boring
production. Standard RBMs are capable
of boring at angles between 45 degrees
and 90 degrees from horizontal, and with
minor adjustment can actually bore at
angles between 45 degrees and hori-
zontal.
A whole host of methods of mechani-
cal raise and shaft excavation have been
developed around the use of the RBM.
These include boxhole boring, blind
shaft boring, rotary drilling, down rea-
ming, pilot up/ream down, pilot down/
ream down, hole opening, and BorPak.
Alternative boring
methods
Boxhole boring is used to excavate raises
where there is limited access, or no access
at all, to the upper level. The machine is
set up at the lower level, and a full dia-
meter raise is bored upward. Stabilizers
are periodically added to the drill string
to reduce oscillation and bending stress-
es. Cuttings gravitate down the hole and
are deflected away from the RBM at the
lower level.
Blind shaft boring is used where access
to the lower level is limited, or impos-
sible. A down reaming system is used,
in which weights are attached to the
reamer mandrel. Stabilizers are located
above and below the weight stack to
ensure verticality of the hole. Cuttings
are removed using a vacuum or reverse
circulation system.
Rotary drilling is used for holes up
to 250 mm-diameter, and is similar in
concept to pilot hole drilling in that a bit
is attached to the drill string to excavate
the required hole size.
Down reaming involves drilling a
conventional pilot hole and enlarging it
to the final raise diameter by reaming
from the upper level. Larger diameter
raises are achieved by reaming the pilot
hole conventionally, and then enlarging
it by down reaming. The down reamer
is fitted with a non-rotating gripper and
thrust system, and a torque-multiply-
ing gearbox driven by the drill string.
Upper and lower stabilizers are installed
to ensure correct kerf cutting and to re-
duce oscillation.
Pilot up/ream down was a predeces-
sor of modern raise boring techniques
using standard drilling rigs. Pilot down/
ream down, or hole opening, employs
a small diameter reamer to follow the
pilot hole. Stabilizers in the drill string
prevent bending.
The BorPak is a relatively new ma-
chine for blind hole boring which climbs
up the raise as it bores. It comprises a
guided boring machine, power unit,
launch tube and transporter assembly,
conveyor and operator console. Cuttings
pass through the centre of the machine,
down the raise and launch tube, and onto
the conveyor. The BorPak has the poten-
tial to bore holes from 1.2 m to 2.0 m-
diameter at angles as low as 30 degrees
from horizontal. It eliminates the need
for a drill string and provides the steer-
ing flexibility of a raise climber.
Raise boring machine
The raise boring machine (RBM) pro-
vides the thrust and rotational forces ne-
cessary for boring, as well as the equip-
ment and instruments needed to control
and monitor the process. It is composed
of five major assemblies: the derrick;
the hydraulic, lubrication, and electrical
systems; and the control console.
The derrick assembly supplies the ro-
tational and thrust forces necessary to
turn the pilot bit and reamer, as well as
to raise and lower the drill string. Base-
plates, mainframe, columns and head-
frame provide the mounting structure
for the boring assembly. Hydraulic cy-
linders provide the thrust required for
lowering and lifting the drillstring, and
for drilling and reaming. The drive train
assembly, comprising crosshead, main
drive motor, and gearbox, supplies the
Typical raise boring underground site showing overhead clearance.
Boxhole boring.
Clearance for derrick
erection from the
transporter system
Overhead
clearance
for complete
derrick
extension

Raise Boring
rotational power to the drill string and
cutting components.
Four types of main drive motor
systems are available:
AC, DC, hydraulic and VF. The gearbox
mounts directly to the main drive motors,
employing a planetary reduction for its
compactness. The hydraulic power unit
is skid-mounted, and comprises the ne-
cessary reservoir, motors, pumps, valves,
filters and manifolds.
The lubrication system ensures
proper delivery of lubricating oil to the
high-speed bearings and other selected
components of the drive train assembly
gearbox, and comprises pump, motor,
filter, heat exchanger, flow meter, and
reservoir with level gauge, thermometer
and breather.
The electrical system assembly con-
sists of an enclosed cabinet containing
the power and control distribution hard-
ware and circuitry for the entire raise
boring operation.
The control console provides for both
electrical and hydraulic functions, offe-
ring meter readouts for main operating
parameters.
Computerization of the raise boring
functions is also offered, using Atlas
Copco’s well-tried PC based RCS
system.
Acknowledgements
This article has been prepared using
The Raise Boring Handbook, Second
Edition, researched and compiled by
Scott Antonich, as its main reference.
Typical operating installation of the BorPak machine.
Robbins 73RM-VF set up in a workshop.

Robbins Raise Drills
... keep on raising
Fax: +46 19 670 7393
www.raiseboring.com
Ever since the first Robbins raise drill was built in 1962, it
has been a constant success. By meeting customer needs
through innovation, reliability and an unrivalled product
range, we have gained the lion’s share of the global market
– and we intend to keep it that way!
Robbins Raise Drill Systems produce shafts and raises from
0.6 m to 6.0 m in diameter, and up to 1000 m in length.

Mechanized Bolting
Specializing for safety
There was a time when underground
mining and safety were terms not com-
monly referred to in the same sentence.
However, times have changed, and today
safety is given a place of prominence in
the operational priorities of the mining
industry.
Freshly blasted openings leave con-
siderable areas of loose rock, which must
be removed to prevent fall-of-ground
injuries. Improvements in drilling and
blasting techniques have helped to signi-
ficantly reduce the amount of this loose
rock. Scaling, which is the most hazard-
ous part of the work cycle, is used to
remove loose rock.
Subsequent blasting might result in
additional rock falls, especially in frac-
tured ground conditions. Screening or
shotcreting, as a means of retention of
this loose rock, is often used in com-
bination with rockbolting. Screening,
which is a time-consuming operation,
is common practice in Canada and
Australia. Since the 1960s and 1970s,
considerable effort has been spent on
mechanizing underground operational
activities, including the rock excavation
cycle. Within the drill-blast-mucking
cycle repeated for each round, the drill-
ing phase has become fully mechanized,
with the advent of high productivity hy-
draulic drill jumbos.
Similarly, blasting has become an ef-
ficient process, thanks to the develop-
ment of bulk charging trucks and easily
configured detonation systems. After
only a short delay to provide for ade-
quate removal of dust and smoke by high
capacity ventilation systems, the mo-
dern LHD rapidly cleans out the muck
pile.
These phases of the work cycle have
been successfully mechanized, and mo-
dern equipment provides a safe operator
environment.
By contrast, the most hazardous ope-
rations, such as scaling, bolting and
screening, have only enjoyed limited
progress in terms of productivity im-
provements and degree of mechaniza-
tion. The development of mechanized
scaling and bolting rigs has been slower,
mainly due to variations in safety rules
and works procedure in specific rock
conditions.
To summarize, equipment manufac-
turers have had difficulty in providing
globally accepted solutions. Nevertheless,
there is equipment available from Atlas
Copco to meet most of the current de-
mands of miners and tunnellers.
Mechanization stages
Various methods of mechanized bolting
are available, and these can be listed
under the following three headings.
Manual drilling and bolting
This method employs light hand held
rock drills, scaling bars and bolt instal-
lation equipment, and was in wide-
spread use until the advent of hydraulic
drilling in the 1970s. Manual methods
are still used in small drifts and tun-
nels, where drilling is performed with
handheld pneumatic rock drills. The
bolt holes are drilled with the same
equipment, or with stopers. Bolts, with
or without grouting, are installed manu-
ally with impact wrenches. To facilitate
access to high roofs, service trucks or
cars with elevated platforms are com-
monly used.
Semi-mechanized drilling and
bolting
The drilling is mechanized, using a hy-
draulic drill jumbo, followed by manual
installation of the bolts by operators wor-
king from a platform mounted on the
Mechanized bolting and screening
Utilization is the
key
In tunnelling operations, it is quite
common to use the same equip-
ment for all drilling requirements.
These days, a single drill rig can
accommodate drilling for face
blasting, bolt holes, protection
umbrellas, and drainage. As there
are normally only one or two faces
available for work before blast-
ing and mucking, it is difficult to
obtain high utilization for special-
ized equipment such as mecha-
nized bolting rigs. By contrast, in
underground mining, especially
where a number of working areas
are accessible using methods such
as room and pillar, high utilization
of specialized equipment can be
expected. This is where mecha-
nized bolting and screening is rap-
idly taking root, for speed, safety
and consistency.
Mechanized scaling with hydraulic hammer.

Mechanized Bolting
drill rig, or on a separate vehicle. The
man-basket, as a working platform,
limits both the practical working space
and the retreat capability in the event of
falling rock. In larger tunnels, the bolt
holes are drilled with the face drilling
jumbo.
Fully mechanized work cycle
A special truck, equipped with boom
mounted hydraulic breakers, performs
the hazardous scaling job with the ope-
rator remotely located away from rock
falls. Blast holes are drilled in the face
using a drill jumbo, and all functions in
the rock support process are performed
at a safe distance from the rock to be
supported. The operator controls every-
thing from a platform or cabin, equipped
with a protective roof.
Where installation of steel mesh is
undertaken, some manual jobs may still
be required. Mesh is tricky to handle,
because of its shape and weight, and
this has hampered development of fully
automated erection.
Quality of bolting
In 1992, it was reported that independ-
ent studies were indicating that as many
as 20-40% of cement and resin grouted
bolts in current use were non-functional.
Tunnellers were reporting that they were
not installing bolts close to the working
face because they might fall out when
blasting the round. Obviously, a large
proportion of rockbolts were being in-
stalled for psychological reasons, rather
than for good roof and face support
and a safe working environment.
However, by using a mechanized in-
stallation procedure, the quality of in-
stallation improves. The bolt can be
installed directly after the hole has been
drilled; the grout can be measured and
adjusted to the hole size; and bolt instal-
lation can be automated, which is espe-
cially important when using resin car-
tridges, where time and mixing speed
are crucial. It can be proved that mech-
anization and automation of the rock-
bolting process offers improved quality
and safety.
While mining companies and eq-
uipment manufacturers, especially in
Canada, focused their development on
improving semi-mechanized roof sup-
port, evolution in Europe concentrated
on fully mechanized bolting. During the
1990s, progress accelerated, and today,
around 15% of all bolting in underground
mines worldwide is carried out by fully
mechanized bolting rigs.
However, compared to mechanization
of face drilling and production drilling,
this level of acceptance is far from im-
pressive, and the industry has been slow
to accept the principle.
The obvious positive safety aspects
of mechanized rockbolting have been
sidelined by considerations relating to
the scale of operations and the type of
equipment available. Hence the higher
acceptance in mining, where several fa-
ces are operated simultaneously. For
tunnelling applications, where the rate
of advance is of prime importance, the
economic criteria might be different.
Also, as there are more functions in-
corporated into the average rockbolter
when compared to a drill jumbo. Bol-
ting units are exposed to falling rock,
or cement from grouting, both of which
impact upon maintenance costs.
Significant improvements
When Atlas Copco introduced its cur-
rent series of mechanized rock bolting
units, a wide range of radical improve-
ments was incorporated.
Based on the unique single feed sy-
stem with cradle indexing, the latest me-
chanized bolting unit, MBU, is consid-
erably more robust, and less sensitive to
falling rock, than its predecessor. Holes
are easy to relocate, and the stinger cyl-
inder improves collaring and the ability
to install bolts under uneven, rugged roof
conditions.
Major re-engineering has resulted
in 30% fewer parts. Less maintenance
and stock inventory are required, and
high availability has been recorded.
Furthermore, the chain feeds used
in the new Boltec series feature an
automatic tensioning device, which
guarantees even and strong feed force
for the rock drill, while a stinger cylin-
der improves collaring and the ability
to work under uneven roof conditions.
The completely redesigned drill steel
support provides sufficient space for bolt
plates passing through, and facilitates
extension drilling.
The most outstanding benefit, how-
ever, is the computer-based Rig Control
System, RCS. This system, which has
already been successfully incorporated
Mechanized cablebolting with Cabletec LC.

Mechanized Bolting
on the latest Boomer and Simba series
of drill rigs, offers simplified fault de-
tection, operator interactivity, and the
basis for logging, storing and transfer-
ring of bolt installation production and
quality data.
The Boltec is equipped with the new
rock drill, the COP 1132, which is short
and compact, and features a modern
double damping system which, com-
bined with the RCS, transmits maxi-
mum power through the drill string. The
long and slender shaped piston, which
is matched to the drill steel, permits
high impact energy at high frequencies
resulting in long service life of drill-
ing consumables and efficient drilling.
Furthermore the COP 1132 is fully
adjustable for various rock conditions.
Versatility and ergonomics
Modern bolting rigs can handle instal-
lation of most types of rockbolts com-
monly used today such as Swellex, as
well as resin and cement grouted rebars.
Using the new Boltec series based on
RCS, the operator copes easily with the
more demanding cement grouting and
resin cartridge shooting applications, by
controlling all functions from the cabin
seat.
Up to 80 cartridges can be injected
before the magazine needs refilling.
Also, because meshing is often carried
out in combination with bolting, an op-
tional screen handling arm can be fitted
parallel to the bolt installation arm, to
pick up and install the bulky mesh scre-
ens. Up to 5 different pre-programmed
cement-water ratios can be remotely
controlled.
The new generation rigs offer the ope-
rator a modern working environment in
a safe position. Low positioned, power-
ful lights provide outstanding visibility
of the entire drilling and bolting cycle.
The new Boltec family has two mem-
bers equipped with RCS and the fully
automated cement handling system: the
Boltec MC, for bolt lengths of 1.5-3.5 m
and roof heights up to 8 m; and the
larger Boltec LC for bolt lengths of 1.5-
6.0 m, primarily for large tunnelling
projects having roof heights of up to 11
m. The positive response from operators
and mechanics confirms that this latest
generation of Boltec will pave the way
for further acceptance of mechanized
bolting.
Screen installation
In Canadian mines the combination of
rockbolts and screen, or wire mesh, is
commonly used for rock support. Since
rock reinforcement is potentially one of
the most dangerous operations in the
work cycle, mechanized rockbolting has
become more popular. A Boltec MC
using RCS, equipped with screen han-
dling arm, has been in use for a couple
of years at Creighton Mine installing
screen with split-set bolts.
In general, the screen is 3.3 m-long x
1.5 m-wide, and is installed in both roof
and walls, down to floor level. Typical
spacing of bolts is 2.5 ft. Three differ-
ent types of bolts are used, depending
on rock conditions, and all bolting must
be done through the screen, with the ex-
ception of pre-bolting at the face. In
general, galvanized split-set are used
for wall bolting, while resin grouted
rebar or mechanical bolts are used in
the roof, and Swellex in sandfill.
Once the screen handling arm has
picked up a screen section and fixed
it in the correct position, the powerful
COP 1132 hydraulic rock drill quickly
completes the 35 mm diameter, 6 ft
and 8 ft holes. The bolting unit remains
firmly fixed in position after the hole
is drilled, and the cradles are indexed,
moving the bolt, with plate, into posi-
tion. The bolt feed, combined with the
Boltec LC with screen handling arm.

Mechanized Bolting
impact power from a COP 1025 ham-
mer, is used for installing split-set bolts.
The complete rock reinforcement job is
finished in just a few minutes.
Boltec MC flexibility
The Boltec MC delivered to the Creighton
mine is capable of handling several ty-
pes of bolts: split-set, mechanical an-
chors, resin grouted rebar and Swellex.
The switch of accessories between dif-
ferent bolt types takes 5-10 minutes. To
minimize water demand during drill-
ing, water mist flushing is used. The
Boltec MC can also be equipped with a
portable operator’s panel connected by
a 50 m-long cable.
Cartridge shooting is remote con-
trolled for the Boltec MC, and up to
80 cartridges can be injected before
refilling is needed. A unique feature is
the possibility to use two different types
of cartridges, with fast or slower curing
times, housed separately in the dual
cartridge magazine. The operator can
select how many cartridges of each type
to inject into any hole. For instance, he
can inject two fast curing cartridges for
the bottom of the hole, and follow up
with slower-curing cartridges for the
rest of the hole, all without leaving his
operator’s panel!
Cabletec LC for cable
bolting
Atlas Copco has developed a fully mech-
anized rig for drilling and cable bolt-
ing by a single operator. The first unit
went into operation some years ago at
Outokumpu’s Kemi chromite mine
in northern Finland, and a second unit
went to Chile. Today, a significant nu-
mber of units are sold to many mines
around the world. The Cabletec LC is
based on the long hole production drill-
ing rig Simba M7, with a second boom
for grouting and cable insertion.
The booms have an exceptionally
long reach and can drill a line of up to
4.7 m of parallel holes from the same
rig setup. Likewise, the booms can reach
up to 8 m roof height, allowing the
Cabletec LC to install up to 25 m-long
cable bolt holes in underground mining
applications such as cut and fill mining
and sub level stoping. Furthermore, the
drill unit can rotate 360 degrees and
tilt 10 and 90 degrees, backwards and
forwards respectively. The new rig is
designed on proven components and
technology featuring two booms - one
for drilling and the other for grouting
and cable insertion. It also features an
on-board automatic cement system with
WCR (Water Cement Ratio) control.
All these features facilitate a true single
operator control of the entire drilling
and bolting process. The two-boom con-
cept has drastically reduced the entire
drilling and bolting cycle time and, by
separating the drilling and bolting func-
tions, the risk of cement contaminat-
ing the rig is eliminated. The operator
is able to pay full attention to grouting
and cable insertion, while drilling of the
next hole after collaring is performed
automatically, including pulling the rods
out of the hole.
Cabletec is equipped with the well
proven COP 1838 ME hydraulic rock
drill using reduced impact pressure with
R32 drill string system for 51 mm hole
diameter or R35 for 54 mm holes. Alter-
natively, the COP 1638 rock drill can be
used for soft rock conditions. Maximum
hole length is 32 m using 6 ft rods and
RHS. The cable cassette has a capacity
of 1,700 kg and is readily refilled thanks
to the fold-out cassette arm. The cement
mixing system is automated, comprising
a cement silo containing 1,200 kg of dry
cement. The cement is mixed accor-
ding to a pre-programmed formula, re-
sulting in a unique quality assurance
of the grouting process. The cement
silo capacity is adaptable for up to 25
m-long, 51 mm-diameter holes.
To date, most holes have been drilled
in the 6-11 m range, for which the rig
has grouted and installed cable at a rate
of more than 40 m/h. Depending on type
of geology and hole diameter chosen,
the drilling capacity can vary between
30 and 60 m/h.
Conclusion
Rock support, including scaling, bolt-
ing, screening, and cable bolting, is still
the bottleneck in the working cycle in
underground mining and tunnelling
applications. Clearly, any reduction in
the time required to install the neces-
sary support has a direct impact on the
overall cycle time, and consequently the
overall productivity and efficiency of
the operations. The fully mechanized
bolting rig of today, incorporating all of
the benefits of modern computer tech-
nology, constitutes a major leap towards
improved productivity, safety and ope-
rator environment.
Hans Fernberg and Patrik Ericsson
Cabletec drilling and installing cablebolts upwards, and Simba drilling blast holes downwards at Kemi mine.
Cabletec main technical data
Length: 13.9 m
Width: 2.7 m
Height: 3.3 m
Turning radius: 4.3m / 7.5 m
Cabletec
Simba

steep Mining
Sublevel open stoping
Sublevel open stoping (SLOS) is used
for mining mineral deposits with: steep
dip where the footwall inclination exce-
eds the angle of repose; stable rock in
both hanging wall and footwall; compe-
tent ore and host rock; and regular ore
boundaries. SLOS recovers the ore in
large open stopes, which are normally
backfilled to enable recovery of pillars.
The orebody is divided into separate
stopes, between which ore sections are
set aside for pillars to support the roof
and the hanging wall. Pillars are nor-
mally shaped as vertical beams, across
the orebody. Horizontal sections of ore
are also left as crown pillars.
Miners want the largest possible sto-
pes, to obtain the highest mining effi-
ciency, subject to the stability of the rock
mass. This limits their design dimen-
sions.
Mining in steep orebodies
Based on gravity
The different mining methods can
be divided into two groups based
on the dip of the orebody. Where
the dip exceeds 50 degrees, bla-
sted material will gravitate to a
collection level where loading and
main haulage are carried out. The
dimensions of mineral deposits
vary greatly, from massive for-
mations stretching over several
square kilometres, to half metre-
wide quartz veins containing
some 20 g/t gold. In recovering
the minerals, the miners attempt
to leave hangingwall and footwall
waste rock intact. In the larger
deposits, the drift size does not
normally restrict the size of eq-
uipment. When the mineraliza-
tion narrows to a few metres only,
it can become self-defeating to
excavate space for standard ma-
chines, because of dilution. For
such situations, a selection of slim
machines is available from Atlas
Copco, capable of mechanized
mining in drifts from 2 m-wide.
These include a face drilling jum-
bo for narrow drifting, a similar
longhole drilling rig, and a 2 cu m
loader.
Sublevel open stoping layout.
Long-hole
drilling and
blasting Drill
access 1
Drill
access 2
Stope
Blasted ore
Draw point
Undercut fan
blasting
Loading
crosscut
Transport drift
Bighole stoping layout.
Long-hole
drilling and
blasting
Stope
Blasted ore
Draw point
Undercut
Loading
crosscut
Transport drift

steep Mining
Sublevel drifts are located within the
orebody, between the main levels, for
longhole drilling of blast patterns. The
drill pattern accurately specifies where
the blastholes are collared, and the depth
and angle of each hole.
Drawpoints are located below the
stope to enable safe mucking by LHD
machines, which may tip into an adja-
cent orepass, or into trucks or rail cars.
The trough-shaped stope bottom is ty-
pical, with loading drifts at regular
intervals. Nowadays, the loading level
can be integrated with the undercut, and
mucking out performed by a remote
control LHD working in the open stope.
This will reduce the amount of drift
development in waste rock.
Sublevel stoping requires a straight-
forward shape of stopes and ore bound-
aries, within which only ore is drilled.
In larger orebodies, modules of ore may
be mined along strike, as primary and
secondary stopes.
Bighole stoping
Bighole stoping is an up-scaled variant
of sublevel open stoping, using longer,
larger-diameter DTH blastholes, rang-
ing from 140 to 165 mm. Blast patterns
are similar to SLOS, but with holes up
to 100 m-long. A pattern with 140 mm
blastholes will break a rock slice 4 m-
thick, with 6 m toe spacing. DTH drill-
ing is more accurate than tophammer
drilling, allowing the vertical spacing
between sublevels to be extended, from
40 m with SLOS mining, to 60 m with
bighole stoping. However, the risk of
damage to the rock structures has to be
taken into account by the mine plan-
ners, as the larger holes contain more
explosives.
Shrinkage stoping
In shrinkage stoping, traditionally a
common mining method, ore is excavated
in horizontal slices, starting from the
stope bottom and advancing upwards.
Part of the blasted ore is left in the stope,
to serve as a working platform, and to
give support to the stope walls.
Blasting swells the ore by about 50%,
which means that a substantial amount
has to be left in the stope until mining
has reached the top section, following
which final extraction can take place.
Shrinkage stoping can be used for ore-
bodies with: steep dips; comparatively
stable ore and sidewall characteristics;
regular ore boundaries; and ore unaf-
fected by storage (some sulphide ores
oxidize, generating excessive heat).
The development consists of: haulage
drift and crosscuts for mucking at stope
bottom; establishment of drawpoints and
undercut; and a raise from the haulage
level passing through the undercut to the
VCR primary stoping.
Loading draw
points
Primary stope no2
undercut and drilling
done
Drill
overcut
Crater
blasting
charges
Primary
stope no1
in production
Shrinkage stoping layout.
Drawpoints
or chutes
Transport drift
Ore left in stope
Cross cut for loading
Raise
Timbered manway
(also ventilation)

steep Mining
main level, providing access and venti-
lation to the working area.
Drilling and blasting are carried out
as overhead stoping. The rough pile of
blasted ore prevents the usage of mecha-
nized equipment, making the method
labour-intensive. As such, working con-
ditions are hazardous, and a large part
of the ore has to be stored until final
extraction. Despite these drawbacks,
shrinkage stoping is still used, espe-
cially for small-scale operations.
Vertical crater retreat
Vertical Crater Retreat (VCR) applies to
orebodies with steep dip and competent
rock in both ore and host rock. Part of
the blasted ore will remain in the stope
over the production cycle, serving as
temporary support. This mechanized
method can be regarded as a consider-
ably safer form of shrinkage stoping, as
no men have to work inside the stope.
VCR was originally developed by
the Canadian mining company INCO,
and uses the crater blasting technique
of powerful explosives in large diameter
holes. Concentrated spherical charges
are used to excavate the ore in horizon-
tal slices, from the stope bottom up-
wards. The ore gravitates to the stope
bottom draw points, and is removed by
loaders. Each stope is cleaned out before
backfilling with cemented hydraulic fill.
Development for VCR stoping con-
sists of: a haulage drift along the ore-
body at the drawpoint level; a draw-
point loading arrangement underneath
the stope; an undercut; and an overcut
access for drilling and charging.
The ore in a stope block is drilled from
the overcut excavation using DTH rigs.
Holes, mainly vertical, are drilled down-
ward, breaking through into the under-
cut. Hole diameters vary from 140 to
165 mm, commonly spaced on a 4 m x
4 m grid.
From the overcut, powerful spherical
charges are positioned by skilled crew
in the lower section of the blast hole,
at specified distances from the stope
roof. The hole depth is measured, and
it is stemmed at the correct height. Ex-
plosive charges are lowered down each
hole and stemmed, usually to blast a 3 m
slice of ore, which falls into the space
below.
VCR charging is complex, and its
techniques have to be mastered in order
to avoid damaging the surrounding rock.
Cut and fill mining
Cut-and-fill mining is applied to mining
steeply dipping orebodies, in strata with
good to moderate stability, and a com-
paratively high-grade mineralization.
It provides better selectivity than
SLOS and VCR mining, and is preferred
for orebodies with irregular shape and
scattered mineralization, where high
grade sections can be mined separately,
and low grade rock left in the stopes.
However, men and machines are work-
ing within the stope, which detracts
from the safety of the operation.
Cut-and-fill mining excavates the ore
in horizontal slices, starting from a bot-
tom undercut, advancing upward. The
ore is drilled, blasted, loaded and re-
moved from the stope, which is then
backfilled with deslimed sand tailings
from the dressing plant, or waste rock
carried in by LHD from development
drives. The fill serves both to support
stope walls, and as a working platform
when mining the next slice.
Before filling, stope entries are bar-
ricaded and drainage tubes installed.
The stope is then filled with sand to
almost full height, and cement is mixed
into the final pours, to provide a solid
floor for mobile machines to operate.
As no rib pillars are left, and the crown
pillar is commonly taken out in a single
large blast once sufficient expansion
room is available, most of the ore can
be recovered with a minimum of waste
dilution.
Development for cut-and-fill mining
includes: a footwall haulage drive along
the orebody at the main level; an under-
cut of the stope area, with drains for
water; a spiral ramp in the footwall,
with access drive to the undercut; and a
raise connection to the level above, for
ventilation and filling material.
The stope face appears as a wall, with
an open slot at the bottom, above the fill.
Breasting holes are drilled by a rig, char-
ged and blasted, with the slot under-
neath providing swell space for the bla-
sted rock.
The mineralization shows in the stope
face, where it can be inspected by geolo-
gists. The drill pattern can be modified,
to follow variations in ore boundaries.
Sections with low grade can be left in
place, or deposited in adjacent mined-
out stope sections. Mining can divert
from planned stope boundaries, and
Cut-and-fill stope layout.
Ramp
Ramp
Hydraulic
sandfill
Hydraulic
sandfill
Ventilation tube

steep Mining
recover enclosures of mineral from the
host rock. The smooth fill surface and
controlled fragmentation are ideal for
LHD loaders, the standard vehicle for
mucking and transport in cut-and-fill
mines. Tramming distances from stope
to orepass, located strategically for the
ramps, must be within convenient range.
Alternatively, the orepasses may be
constructed inside the stope using steel
lining segments installed in advance of
each sand layer. To increase productivity
and safety, there is a trend towards re-
placing cut and fill mining with bench
stoping and fill, as at Mt Isa, Australia,
and towards open stoping with paste
fill, as at Garpenberg, Sweden.
Sublevel caving
Sublevel caving (SLC) adapts to large
orebodies, with steep dip and continuity
at depth. Sublevel footwall drifts have to
be stable, requiring occasional rockbolting
only. The hangingwall has to fracture
and collapse, following the cave, and
subsidence of the ground surface above
the orebody has to be tolerated.
Caving requires a rock mass where
both orebody and host rock fracture un-
der controlled conditions. As the mining
removes rock without backfilling, the
hanging wall carries on caving into the
voids. Continued mining results in subsi-
dence of the surface, where sinkholes
may appear. Continuous caving is im-
portant, to avoid creation of cavities in-
side rock, where a sudden collapse could
induce an inrush.
SLC extracts the ore through sublev-
els, which are developed in the orebody
at regular vertical spacing. Each sublev-
el features a systematic layout with par-
allel drifts, along or across the orebody.
In wide orebodies, sublevel drifts start
from the footwall drive, and continue
across to the hanging wall. In narrow
orebodies, sublevel drifts branch off
longitudinally in both directions from
a central crosscut drive.
Development to prepare SLC stopes
is extensive, and mainly involves driving
multiple headings to prepare sublevels.
A ramp connection is needed to connect
different sublevels, and to communicate
with main transport routes. Orepasses
are also required, at strategic locations
along sublevels, connecting to the main
haulage level.
A section through the sublevel area
will show drifts spread across the ore-
body, in a regular pattern, both in verti-
cal and horizontal projections. The dia-
mond shaped area, which can be traced
above each drift, delineates the ore vo-
lume to be recovered from that drift.
Longhole rigs drill the ore section
above the drift, in an upwards fanspread
pattern, well ahead of production.
Blasting on each sublevel starts in
sequence at the hanging wall, common-
ly using an upwards raise to provide ini-
tial expansion, and mining then retreats
toward the footwall. Adjacent crosscuts
are mined at a similar pace, with upper
sublevels maintained ahead of lower
sublevels, to preserve the cave and avoid
undermining. Each longhole fan is bla-
sted separately, and the ore fills the
drawpoint. Mucking out by LHD con-
tinues until the waste dilution reaches
the set limit. See the figure showing ore/
Sublevel caving layout.
Caved
hanging wall
Production =
Blasting and
loading
Charging
Drilled
Sublevels
Footwall drift
Ore pass
Haulage level
Long-hole
drilling
Development of
new sublevels
000 20 40 60 80 100 120 %
20
40
60
80
100
Dilution
entry
point
77%Ore
33%Waste
Ore + Waste
Orevolumeinslice=100%
ore
Typical ore/waste
ratio during
a mucking cycle.

steep Mining
waste ratio during a typical mucking
cycle. The LHD then moves to a freshly
blasted crosscut, while the charging team
prepares the next fan for blasting.
Sublevels are designed with tram-
ming distances matched to particular
sizes of LHD loaders. Mucking out is,
like the other procedures in sublevel ca-
ving, very efficient, and the loader can
be kept in continuous operation. Waste
dilution in SLC varies between 15%
and 40%, and ore losses may be 15% to
25%, depending on local conditions.
Dilution is of less influence for ore-
bodies with diffuse boundaries, where
the host rock contains low-grade min-
erals. Similar rules apply to magnetite
ores, which are upgraded by simple mag-
netic separators. Sulphide ores, however,
are refined by costly flotation processes,
so dilution has to be closely controlled.
SLC is schematic, and repetitive,
both in layout and working procedures.
Development drifting, production drill-
ing of long holes, charging, blasting and
mucking out are all carried out separate-
ly, with work taking place at different
levels simultaneously.
There is always a place for the ma-
chines to work, which integrates mech-
anization into efficient ore production.
Consequently, the SLC method is well
suited for a high degree of automation
and remote operations, with correspon-
ding high productivity. Drawbacks are
high waste dilution and substantial ore
losses.
The Swedish iron ore producer LKAB
is one of the world's leading producers
of upgraded iron ore products. Vast ex-
perience and successful progress have
been accumulated at their two large un-
derground mines at Kiruna and Malm-
berget in northern Sweden by adop-
ting SLC as the predominant mining
method
The articles in the book Underground
Mining Methods, edited by William A.
Hustrulid and Richard L. Bullock, chap-
ters 43, 46 and 47 give valuable in-depth
information about the operations and
the caving parameters, both in general
and at LKAB in particular.
Block caving
Block-caving is a large scale production
mining method applicable to low grade,
massive orebodies with: large dimen-
sions both vertically and horizontally; a
rock mass that behaves properly, break-
ing into blocks of manageable size; and
a ground surface which is allowed to
subside.
These rather unique conditions limit
block-caving applications to special mi-
neral deposits such as iron ore, low-grade
copper and molybdenum mineraliza-
tions, and diamond-bearing kimberlite
pipes.
Block caving is based on gravity com-
bined with internal rock stresses, to frac-
ture and break the rock mass. The dril-
ling and blasting required for ore pro-
duction is minimal, while development
volume is huge. Blocks of orebody may
have areas of several thousands of square
metres, and development may have to
start as much as 10 years in advance of
production.
Caving is induced by undercutting the
block by blasting, destroying its ability
to support the overlying rock. Gravity
forces, in the order of millions of tonnes,
act to fracture the block. Continued pres-
sure breaks the rock into smaller pieces
to pass the drawpoints, where the ore is
handled by LHD loaders or trains. As
fragmentation without drilling and bla-
sting is uneven, a substantial amount of
secondary blasting and breaking can be
expected at the drawpoints.
Development for block caving ap-
plying conventional gravity flow re-
quires an undercut, where the rock mass
underneath the block is fractured by
longhole blasting. Drawbells with fin-
ger raises are excavated beneath the
undercut, to gather broken rock to the
grizzly level, where oversize boulders
are caught and then broken by blasting
or hydraulic hammer. A lower set of finger
raises channels ore from the grizzlies
to chutes for train loading on the main
level.
The intention is to maintain a steady
draw from each block, and records are
kept of volumes extracted from indi-
vidual drawpoints. It is often necessary
to assist the rock mass fracturing by
longhole drilling and blasting in widely
spaced patterns.
Drifts and other openings in the block
caving area are excavated with mini-
mum cross sections for man-entry. Still,
heavy concrete lining and extensive
rock bolting is necessary, to secure the
integrity of mine drifts and drawpoint
openings. Where LHD loaders are used
in the drawpoints, a ventilation level is
added into development plans.
Where the ore block breaks up suc-
cessfully, and the extraction is carried
out evenly from all of the drawpoints,
block caving becomes a low-cost, high-
productivity method, with good ore
recovery and moderate inflow of waste
dilutions. The risks are high, but the
result can be extremely favourable. This
method is often used when converting
an open pit operation into an under-
ground mine where surface production
can continue while the underground
infrastructure is prepared.
Hans Fernberg
Undercut
level
Drawbells
Picking
hammer
Haulage level
Production level
Ventilation
level
Ore pass
Pickhammer
level
Block caving layout.

We always take a hard view on costs
Working with Atlas Copco means working with highly
productive rock drilling solutions. It also means sharing a
common cost-cutting challenge. Like you, we are always
looking for new and effective ways to squeeze your
production costs – but never at the expense of quality, safety
or the environment.
Mining and construction is a tough and competitive business.
Fortunately, our view on cutting costs is just as hard.
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Fax: +46 8 670 7393
www.atlascopco.com

flat Mining
Room and pillar
Room and pillar is designed for mining
of flat, bedded deposits of limited thick-
ness. Examples are sedimentary depo-
sits, like copper shale, limestone or
sandstone containing lead, coal seams,
salt and potash layers, limestone and
dolomite.
The method recovers the mineraliza-
tion in open stopes, leaving pillars of
ore to support the roof. To recover the
maximum amount of ore, miners aim to
leave smallest possible pillars behind,
because these are difficult and expen-
sive to recover. The roof must remain
intact, and rockbolts are used exten-
sively as rock reinforcement. Rooms
and pillars are normally arranged in
regular patterns, and can be designed
with circular pillars, square pillars, or
elongated walls separating the rooms.
Classic room and pillar applies to
flat, bedded deposits with moderate to
large thickness, also to inclined depos-
its with larger thickness. Mining the
orebody creates large openings, where
trackless machines can travel on the
flat floor. Orebodies with large vertical
height are mined in horizontal slices,
starting at the top and benching down
in steps.
Post room and pillar applies to in-
clined orebodies, of dip angle from 20
to 55 degrees, with large vertical height,
where mined out space is backfilled.
The fill keeps the rock mass stable,
and serves as the work platform while
mining the next ore slice.
Step room and pillar is an adaptation
of trackless mining to orebodies with
too steep a dip for rubber-tyred vehi-
cles to operate in a regular room and
pillar layout. Haulage drifts and stopes
are therefore angled diagonally across
the dip, to create work areas with level
floors off which trackless equipment
can work. Mining advances downward,
along the step room angle.
Classic room and pillar
Very little development work is required
to prepare flat-bedded deposits for room
and pillar mining, because access for
ore transport and communication is
through the production rooms.
Ore production in flat room and pil-
lar uses the same drill/blast techniques
as in normal drifting. Where geological
conditions are favourable, large-capacity
drilling rigs and loaders can be used.
High orebodies are mined in slices,
starting at the top, rockbolting the roof
from each bench. Standard crawler rigs
are used for drilling vertical holes and
conventional bench blasting. Horizontal
drilling and flat benching is a more prac-
tical alternative, using the same drilling
equipment.
The blasted ore is loaded using
diesel or cable-electric LHD machines,
and, where height permits, dump trucks
may be used between stope and dump.
In thin orebodies, loading points may
be necessary for transferring ore from
loader to hauler. As all activities are car-
ried out on one or very few levels covering
a large area, there are many faces avail-
able at any time, so high equipment utili-
zation is possible.
Post pillar
Post pillar mining is a crossbreed of room
and pillar and cut and fill mining. Post
pillar mining recovers the mineraliza-
tion in horizontal slices, starting from a
bottom slice, advancing upwards. Pillars
are left inside the stope to support the
Vertical benching
Benching of thicker parts
Pillar
Pillar
Mining in flat orebodies
Nearly horizontal
extraction
Variations on room-and-pillar and
longwall mining techniques have
always been attractive proposi-
tions for mechanization, because
of the near horizontality of such
systems. Until recently, trackless
equipment was limited to a mini-
mum working headroom of 2 m
or more. However, major devel-
opments in Polish copper mines
and in gold and platinum mines
in South Africa have spawned a
new generation of thin-seam and
narrow mining equipment from
Atlas Copco that can work in sub-
stantially less space than previous-
ly thought possible. The Rocket
Boomer S1 L, for instance, has a
tramming height of just 1.3 m, yet
can cover a face area of up to 29
sq m. Likewise, the Scooptram
ST 600LP loader equipped with
video cameras to assist the driver
has a height of only 1.56 m, but still
carries a 6 t payload. Availability
of such machines is already revo-
lutionizing the design approach
to mining flat orebodies.
Classic room and pillar layout.

flat Mining
roof. Mined-out stopes are backfilled
with hydraulic tailings, which might con-
tain cement for added strength, to allow
the next slice to be mined working on
the fill surface. Pillars are extended
through several layers of fill, so that
the material contributes to the support,
permitting a high recovery rate. The fill
allows the stope layout to be modified
to suit variations in rock conditions and
ore boundaries.
Post pillar combines the advantages
of flat-floor cut and fill, with the spa-
cious stopes of room and pillar, while
easy access to multiple production points
favours efficient mechanization. Similar
to cut and fill mining, cable bolting is
commonly carried out to provide safe
reinforcement of the roof several slices
ahead of the current mining.
Step room and pillar
Step room and pillar mining adapts the
inclined orebody footwall for efficient
use of trackless equipment in tabular
deposits with thickness from 2 m to 5 m
and dip ranging from 15 to 30 degrees.
Stopes and haulageways cross the dip
of the orebody in a polar coordinate
system, orienting the stopes at angles
across the dip that can comfortably be
travelled by trackless vehicles. Parallel
transport routes cross the orebody to
establish roadway access to stopes and
for trucking blasted ore to the shaft.
Stopes are attacked from the trans-
port drifts, branching out at the pre-
determined step-room angle. The stope
is advanced forward, in a mode similar
to drifting, until breakthrough into the
next parallel transport drive. Next step
is excavation of a similar drift, or side
slash, one step down dip, adjacent to the
first drive. This procedure is repeated
until the full roof span is achieved, and
an elongated pillar is left parallel with
the stopes. The next stope is attacked
in the same way, and mining continues
downwards, step by step.
Longwall mining
Longwall mining applies to thin, bed-
ded deposits, with uniform thickness
and large horizontal extension. Typical
deposits are coal seams, potash layers
or conglomerates, and gold reefs.
Longwall mining extracts the ore
along a straight front, with large longi-
tudinal extension. The mining area close
to the face is kept open, to provide space
for personnel and mining equipment.
The roof may be allowed to subside at
some distance behind the working face.
Development involves excavation of
a network of haulage drifts, for access
to production areas and transport of ore
to shaft stations. As the mineralization
extends over a large area, haulage drifts
are paralleled by return airways, for ven-
tilation of the workings. Haulage drifts
are usually arranged in regular patterns,
and excavated inside the ore. Coal and
gold longwall production techniques are
similar in principle, but quite different
Post
Pillar
Post pillar mining layout.
1
2
3
4
Stope mined
Numbers indicate
sequence of extraction
Step room and pillar layout.

flat Mining
in terms of mechanization. In the coal
mine, shearers shuttle back and forth
along the face, cutting coal and depositing
it on chain conveyors. The gold reef con-
glomerate is much harder, and difficult
to tackle. South Africa gold mines have
developed their own techniques, using
handheld pneumatic rock drills in reefs
as thin as 1.0 m, which constitutes a
great challenge for equipment manufac-
turers to mechanize. Pillars of timber
or concrete are installed to support the
roof in the very deep mines.
Hans Fernberg
Complete package
Atlas Copco offers three key mining
tools to provide the total solution for
low seam mining applications: drill
rigs, loaders and bolting rigs. These
are all compact and technically ad-
vanced low profile versions, specially
designed for efficient production in
rigorous underground locations: the
Rocket Boomer S1 L face drilling rig
is adapted to this specific type of
mining, with a coverage area between
6 and 29 sq m in a tramming height
as low as 1.3 m; the Boltec SL bolt-
ing rig carrier, boom and bolting unit
have been designed for efficient ope-
ration in roof heights between 1.8 and
2.5 m; and the Scooptram ST600LP
can operate safely in 1.8 m headroom
as one of a range of loaders of vari-
ous capacities.
Dip 13 - 20 o
bench
bench
crosscut
benchingbenching
crosscut
drift
drift
Foot wall
(The Fossum formation)
Hanging wall
(The Venstop formation)
Limestone
(The Steinvika formation)
Horisontal pillar
8 m
Strike
Dip
approx.40m
Room and pillar with benching at Dalen mine, Norway.
Transport
drift
Slashing holes
Blasting barricade
Scraper
Pillars of
timber/concrete to
support roof
©
Atlas Copco Rock Drills AB, 2000
Typical longwall layout. Rocket Boomer S1 L, the cabin version.
Scooptram ST600LP.
Rocket Boomer S1 L, the rear view.

Fax: +46 19 670 7393
www.atlascopco.com
Working with Atlas Copco means working with world-
leading products and services. What’s more, the people
you work with are also the best – committed to creating
the ideal conditions for your mining and construction
operations.
It takes a strong will to get to the top, and a firm hand to
stay there. Our commitment to supply you with the best
rock-drilling solutions is just as strong.
Our commitment is just as strong

Backfilling
Functions of backfill
The original function of backfill in hard
rock mines was to support rock walls
and pillars, and to provide a working sur-
face for continuing mining. This was
initially accomplished by rock fill, and
more often in the present day by hydra-
ulic fill.
If 3-4% of cement is added to a hy-
draulic backfill of concentrator tailings,
and this is topped off in the stope with
a 10% mix, a smooth and hard surface
results. This is useful for mechanized
removal of broken ore from the subse-
quent mining operation, and reduces
dilution from the fill.
Backfill also affords the opportunity
for more selective mining and better re-
covery of ore and pillars, thereby in-
creasing both mine life and total return
on investment.
Other functions of backfill are the
prevention of subsidence, and better
control over ventilation flow through
the mine workings. Cemented hydrau-
lic fill (CHF) or paste backfill may
also be used to stabilize caved areas in
the mine. Backfill is also considered an
essential tool to help preserve the struc-
tural integrity of the mine workings as
a whole, and to help avoid stressing
ground to the point where rock bursts
take place.
Application and design
Fill preparation and placement systems
should be simple and efficient, with
special attention paid to quality control.
Two systems are used: cyclic filling and
delayed filling. In cyclic systems, the
fill is placed in successive lifts, as in
cut-and-fill mining sequences. The fill
can form a platform for the operation
of mining equipment, or mining may
be undertaken below, beside, or through
the backfill.
In delayed backfill, the entire stope is
filled in one operation. In this case, the
fill must be able to stand as an unsup-
ported wall rigid enough to withstand
the effects of blasting. It should allow
adjacent stopes to be extracted with mi-
nimal dilution from sloughing.
A whole host of factors have to be
taken into consideration when design-
ing a backfill regime. The geology and
dimensions of the orebody and its dip
and grade are important factors, as are
the physical and mechanical properties
of both the ore and its host rock. En-
vironmental considerations, fill material
resources, mining method, production
capacity and operations schedules bear
Drift and fill mining sequence.
Backfilling for safety and profit
Permanent support
Empty stopes are frequently back-
filled as a means of providing sup-
port for future mining. Other than
its own body weight, backfill is a
passive support system that has
to be compressed before exerting
a restraining force. Backfill mate-
rial is normally generated by the
mine as waste rock underground,
or as tailings from the surface con-
centrator, so backfilling may serve
a secondary purpose as a means
of disposal of otherwise useless
byproducts. The optimum back-
fill method is clearly related to the
mining method. Costs of backfill
typically range between 10-20% of
mine operating cost, of which ce-
ment represents up to 75%. Paste
fill is gaining in popularity because
it uses unclassified tailings and
less water, but the capital cost of
a paste fill plant is approximately
twice the cost of a conventional
hydraulic fill plant of the same
capacity.
Drift 1
Fill
Drift 2
Fill
Drift 3
Fill
Drift 4
Drift 1
Fill
Drift 2
Fill
Drift 3
Drift 1
Fill
Fencing
Drift 2
Fill
Drift 3
Drift 1
Cemented
Fill
Drift 2
Cemented
Fill
Drift 3
Fencing
A.
B.
C.
D.

Backfilling
on the design, as do the fill mix and
strength attainable using available ma-
terials. Fill quantities will determine the
size of the preparation and placement
systems, and the location and eleva-
tion of stope openings relative to sur-
face facilities such as tailing dams and
concentrator are major considerations.
Mine planners focus on tailormade fill
to save cement costs by strengthening
the fill only where it is required, close
to the stopes to be mined, such as at
Olympic Dam.
Hydraulic fill
Originally, backfill comprised waste
rock, either from development or hand
picked from broken ore. Some larger
mines in the US quarried rock and gra-
vitated it down fill raises to the mine
workings.
Nowadays, rock fill is used for fil-
ling secondary and tertiary stopes,
and is usually a convenient and econo-
mic means of disposal for waste from
development.
The first hydraulic fills were com-
posed of concentrator tailings that would
otherwise have been deposited on the
surface. The mill tailings were cycloned
to remove slimes so that the contained
water would decant.
This fill was transported under-
ground as slurry, composed of around
55% solids, which is the typical under-
flow for thickeners and is the pulp den-
sity normally used for surface tailings
lines.
When the grind from the mill was too
fine for decanting in the stopes, alluvial
sand was employed instead of tailings.
Particles of alluvial sand are naturally
rounded, enabling a higher content to
be pumped than for hydraulic fill made
from cycloned tailings. This type of fill
is commonly referred to as sand fill.
Many mines still employ non-cemented
hydraulic fill, particularly for filling ter-
tiary stopes.
The quantity of drain water from hy-
draulic backfill slurry containing 70%
solids is only a quarter that resulting
from a 55% solids mix.
The porosity of hydraulic backfill is
nearly 50%. It may be walked upon just
a few hours after placement, and will
carry traffic within 24 hours.
Secondary
Primary
Unmined
Tertiary
Unmined
Unmined
Unmined
Unmined
Unmined
Unmined
Unmined
Unmined
UnminedSecondary
PrimaryDesigned stopes
Primary stope extracted
CAF filled due to unmined adjacent stopes
CAF fill
ROCK fill
CAF fill
ROCK fill
2nd Primary stope extracted
CAF filled due to adjacent unmined stopes
Secondary stope extracted
Tertiary stope extracted
Secondary stope extraction
CAF filled on side adjacent to unmined stope
ROCK filled on side adjacent to mined stope
ROCK filled as no adjacent stopes
ROCK fill
CAF fill
CAF fill
Stope extraction and filling sequence at Olympic Dam.
Underhand cut and fill mining sequence.
Slice 1
Slice 2
Slice 3
Slice 4 Face 1 Face 2
Hydraulic fill
Low cement
content
High cement
content and
reinforcement

Backfilling
Planning considerations
Because the density of hydraulic fill is
only about half that of ore, a supplemen-
tary fill material will be needed when
less than half of the tailings can be re-
covered from the mill circuit.
When planning a hydraulic fill
system, a major consideration is water
drainage, collection and disposal, par-
ticularly on deep mines. Getting large
volumes of water back to surface can
be a costly exercise, and installing the
infrastructure may be difficult, expen-
sive and time consuming.
Portland cement added to hydraulic
fill as a binder also adds strength, and
this system of fill in normal and high
density is employed at many mines
around the world. A portion of the
cement may be substituted using fly
ash, ground slag, lime or anhydrite.
If cement is added in the ratio 1:30,
the backfill provides better support for
pillars and rock walls. If the top layer is
then enriched at 1:10, the backfill pro-
vides a smooth and hard surface from
which broken ore can be loaded and re-
moved. Addition of cement reduces ore
dilution from the fill and facilitates se-
lective mining and greater recovery
from both stopes and pillars.
Water decanted from cemented fill
has to be handled appropriately to avoid
cement particles reaching the ore passes
and sumps, where they can have great
nuisance value. One approach is to re-
duce the amount of water in the fill,
increasing solids content to 65-75% and
more in a high-density fill. Additives
can also reduce the water decant from
fill.
Paste fill
Paste fill originally used non-cycloned
mill tailings mixed with cement at the
stope. Coarse tailings permit a very high
solids content of up to 88% to be pum-
ped at high pressure, and high setting
strengths were achieved. Paste is cur-
rently used as a replacement for hydrau-
lic fill, with the cement added at sur-
face. It exhibits the physical properties
of a semi-solid when compared to high-
density fill, which is a fluid.
Because the slimes fraction of the
tailings forms part of the mix, cement
always needs to be added into paste fill,
with 1.5% as the minimum requirement
to prevent liquefaction. Very precise con-
trol of pulp density is required for gra-
vity flow of paste fill, where a 1-2%
increase can more than double pipeline
pressures.
Cemented rock fill
Cemented rock fill (CRF) originally
consisted of spraying cement slurry or
cemented hydraulic fill on top of stopes
filled with waste rock, as practiced at
Geco and Mount Isa mines. Nowadays,
cement slurry is added to the waste rock
before the stope is filled. Where rock is
quarried on surface, it is normally grav-
itated to the mining horizon through a
fill raise, from the base of which trucks
or conveyors are used for lateral trans-
port underground.
Advantages of CRF include a high
strength to cement content ratio, and
provision of a stiff fill that contributes
to regional ground support. CRF is still
selected for some new mines, and many
operators prefer this system.
Cement rich hydraulic fill was once
used for mats where poor ground con-
ditions dictated underhand cut and fill
mining. Since the major cost component
of backfill is the cement at a ratio of
1:2, this fill is not economical, and was
replaced with ready-mix concrete with
10-12% cement content for a standard
3,000 psi, or 20 Mpa, mix.
Ice fill has been used in Norway and
Russia in permafrost regions.
Hans Fernberg
Tailings from concentratorCyclone
Thickener
Vacuum filter
Mixer
Paste pump
Binder cement and/or slag
Paste to the mine
Paste factory – principal flowsheet.
Paste fill plant at Garpenberg, Sweden.

Atlas Copco rock bolts for mining
Energy absorber
(a sliding element)
Pre-calculated
maximum
deformation
1. Roofex at
installation
2.
Energy
absorbing
phase
3.
Roofex at
max load
and max
deformation
Pre-calculated
maximum
deformation
Modern computer-based geotechnical monitoring techniques
indicate that the greatest relaxation or movement of the rock mass
occurs immediately following excavation. They confirm that, after
a certain period, the rock will establish a new equilibrium based
on its own inherent self-supporting capacity. The best quality rock
will remain self-supporting for extensive periods of time without the
need for extra support. As the rock quality declines, support require-
ments increase proportionally. The poorer the quality of the rock, the
greater the degree of support required, and it becomes increasingly
crucial to install reinforcement as quickly and as close to the face
as possible after excavation. Engineers involved in the design of
rock reinforcement systems must satisfy ever increasing demands
to optimize the design to gain maximum safety and economy. The
primary objective in the design of the support system is to assist
the rock mass to support itself. Accordingly, quality and time are
the two main parameters which must be taken into account when
determining the type of rockbolt to be used for rock reinforcement,
in both mining and construction applications.
Swellex
The Swellex concept entails that the rock is secured by immediate
and full support action from the Swellex bolts. The moment the
Swellex bolt is expanded in the hole, it interacts with the rock to
maintain its integrity. The quality of the bolt installation is auto-
matically confirmed when the pump stops, and is independent of
rock mass conditions or operator experience. Controllability means
safety! The Swellex rockbolts are designed to optimize the effective-
ness of each bolt, so the bolting operation matches the required
safety levels as planned by the engineers. See pictures to the left.
Roofex
Roofex features a high quality steel bar inside a smooth plastic shea-
thing which is fixed inside the borehole with cement or resin grout.
The bolt also has an energy absorber which functions as a sliding
element over the steel bar. This allows the bolt to extend outwards
during sudden displacements such as rock burst or seismic events while
still providing constant load capacity. This capability makes the Roofex
rock bolt especially suitable for developing new, deep underground
excavations in poor quality rock or in areas where rock burst or sei-
smic events are frequent. The bolt can be produced in standard lengths
typically used in mining and tunnelling, and the displacement capa-
city can be pre-selected during manufacture. See picture below.
Mathias Lewén
rock reinforcement

Garpenberg, Sweden
History
Mining has been conducted at Garpen-
berg since the 13th century. The present
operations started in 1950-53, when
AB Zinkgruvor developed a new main
shaft and concrete headframe and the
adjacent concentrator. Boliden acquired
the mine in 1957 and completed the
development of a second shaft in 1972,
accessing the 800 m level at Garpenberg
North, having a hoisting capacity of
850,000 t/y and effectively creating a
second and larger mine.
Between these two shafts, the com-
pany located another orebody under a
lake at Dammsjön and, in the 1980s,
considered draining the lake in order
to develop an open pit.
The mineralization in the Garpen-
berg area occurs in a long, narrow syn-
clinal structure which is believed to be
Middle Precambrian, but may have been
remobilized later. The orebodies are
vertically extensive lenses that are usu-
ally narrow, much folded and therefore
twisting and irregular.
Cut and fill
Until very recently all of the ore, sub-
divided in 100 m-high slices, was ex-
tracted by cut-and-fill mining, taking
5-6 m-thick slices drilled horizontally
from 50-300 m-long and up to 15 m-
wide stopes. Rock fill was used in the
bottom cut, and either plain sand or
cemented hydraulic fill above. The
sand comes from the coarse fraction of
the mill tailings, and the fill is supple-
mented by development waste.
Mining starts normally at the centre
of the base level of the stope and pro-
gresses towards the ends and upwards.
The last cut, just below the crown pillar,
is heavily reinforced to facilitate the
recovery of the 8-15 m-high pillar using
up holes drilling and blasting.
The undercut-and-fill method, pro-
gressing downwards, was used in the
Strandgruvan section from the mid-70s
until 2001, when the ore was mined out.
This method provided a safe working
roof in the weak, fractured ore with
unstable footwall, for just the extra
cost of cement and rebar reinforcement.
The method was suited to the orebody
irregularities, and no crown pillar had
to be left or recovered. The introduction
of trackless mining and further explora-
tion of the mineralization in the North
Innovative mining at Garpenberg
One million
tonnes of ore
The Garpenberg mine, located
200 km northwest of Stockholm,
extracts more than 1 million t/y of
ore. The ore is polymetallic and
contains mainly zinc, silver and
also some lead, copper and gold.
Additionally, about 500,000 t of
development waste is excavated
annually. Over recent years, Gar-
penberg has been forced to add
reserves, or reconsider its future.
Happily, more orebodies have
been discovered, and new stoping
methods and drilling technology
introduced. Atlas Copco has co-
operated closely with Garpenberg
management to resolve techni-
cal issues, designing and sup-
plying equipment to suit the
evolving objectives. As a result,
the mine achieved over 1 Mt of
ore in 2005, at very acceptable
grades.
Garpenberg
Dammsjön
Dammsjön Kvarnberget
Lappberget
Finnhyttan
Lina shaft
Gruvsjö shaft
Capacity: 450 000 tpa Smältarmossen
Potential
Production levels
Potential areas outside ore reserves 2005-01
?
?
?
Dammsjö Agmin
500-785 Z
925-1100 Z
910 Z
870 Z
1000-1300 Z
700-
1000 Z
500-
800 Z
1100-
1400 Z
Shaft
Capacity: 850 000 tpa
Tyskgården
Kanal Ore Strand Ore
Kaspersbo
Gransjön
Garpenberg North
0 Z
400 Z
800 Z
1200 Z
0 Z
400 Z
800 Z
1200 Z
1600 Y 2400 Y2000 Y 2800 Y 3600 Y3200 Y 4000 Y 4400 Y 5200 Y4800 Y
Idealized long section at Garpenberg showing all orebodies and shafts.

Garpenberg, Sweden
mine led to the progressive extension
of a 1:7 ramp down to the 910 m level.
In 1998-9, it was extended to the 1,000
m level, increasing the overall length to
8.7 km.
To increase hoisting capacity at the
Garpenberg mine, the new Gruvsjö pro-
duction shaft was completed in 1997
and the original shaft was converted
for personnel and materials hoisting.
With a hoisting capacity of 450,000
t/y, the newer shaft connects with a
ramp accessing the Kanal and Strand
orebodies.
The present operating area extends
approximately 4.5 km SW to NE from
the original shaft to the Gransjön mi-
ning section.
Concentrate production
Upgraded in the early 1990s, the con-
centrator yields separate zinc, lead,
copper and precious metals concen-
trates. The zinc and lead concentrates
are trucked to Gävle harbour and ship-
ped either to Kokkola in Finland or Odda
in Norway. Copper and precious metals
concentrates are railed to the Rönnskär
smelter in Sweden. Since 1957, Boliden
has milled over 20 million tonnes of ore
at Garpenberg.
While the new shaft raised hoisting
capacity, and ramp extension accessed
new ore in the North mine, metals pro-
duction rose to record levels in 1998.
However, this improvement could not
be maintained. Zinc concentrate output
fell from 69,051 t in 1998 to 61,126 t in
2001, despite a rise in ore production.
And proven plus probable ore reserves
declined from 5.7 Mt in 1998 to 2.2 Mt
at 4.0% Zn in 2003, putting a question
mark on the future of the mine.
However, Boliden continued to make
investments in technology for the long
term at Garpenberg. The mine, the com-
pany and the market are now benefiting.
And the geologists are very popular.
New reserves
Probably the most significant event at
Garpenberg during the period of decline
was the discovery in 1998 of a new ore-
body between Garpenberg North and
Dammsjön, named Lappberget. This
encouraged the company to start deve-
lopment in 2000 of an approximately
3.0 km-long drift to connect the 900 m
level at Garpenberg North, first to Lapp-
berget for exploration access, and thence
to the ramp at the 800 m level at Garpen-
berg. During 2001, Boliden started core
drilling at the 800 m and 1,000 m levels
in Lappberget, and by February, 2003
was able to start mining ore from the
new source. Zinc concentrate produc-
tion in the year increased to 80,748 t.
In March, 2004 the connecting drift
was completed, and the formerly sepa-
rate mines have since been regarded and
managed as a single operation. The drift
allows access and infrastructure deve-
lopment of new mineable areas, and
Garpenberg quickly boosted mine output.
The main focus has been on Lappberget,
including driving a ramp close to the ore-
body from the 350 m level, with connec-
tion to the surface scheduled for 2007.
The Tyskgården mineralization, discov-
ered in the early 1980s, also became
accessible, and mining started there in
2003-4. In 2004 Boliden discovered an
extension of the Dammsjön mineraliza-
tion around the 800 m level, and during
2005 a new discovery was made, the
reportedly large and potentially high-
grade Kvarnberget deposit.
Higher output
In 2005, the mine produced 1,102,000 t
ore grading 5.75% Zn, 2.28% Pb, 0.09%
Cu and 117 g/t Ag. Approximately 40%
of the ore came from Lappberget. The
mill yielded 101,000 t of 55.3% zinc
concentrate; 29,000 t of 72% lead con-
centrate with 1,800 g/t silver; 2,800 t
of 15% copper concentrate with 40,000
g/t; and 120 t of precious metal con-
centrate grading 65% lead, 40,000 g/t
silver and 400 g/t gold. Some 967,000
t of tailings retained 0.34% Zn, 0.29%
Pb, 0.02% Cu and 25.5 g/t Ag. By end-
2005 Boliden employed 280 people at
Garpenberg, with a further 70 working
for contractors at the site.
The operation works around the
clock 7 days/week in both the con-
centrator and the mine, with mining
carried out by four production teams
supported by a development crew and
a charging crew. Garpenberg is the
Hedemora Community’s largest private
sector employer.
Since the start of 2005 exploration
has continued, not only adding tonnes,
but also raising average grade. Thanks
to the exploration effort, Garpenberg
also started 2006 with proven reserves
of 4.73 Mt grading 6.0% Zn, 2.5% Pb,
Simba M7 C production drill rig at Garpenberg.

Garpenberg, Sweden
0.1% Cu, 99 g/t Ag and 0.3 g/t Au.
Probable ore brought total reserves up
to 10.67 Mt. That compares with 3.63
Mt of reserves at the beginning of 2005.
Total resources were also increased, from
11.08 Mt in January, 2005 to 13.22 Mt.
This should be sufficient to add another
15-20 years to mine life.
These quantities should increase
further when portions of the orebodies
at Kaspersbo (from 1,000 m down to
1,300 m), Lappberget (500–800 m and
1,100–1,400 m), Dammsjön (500–785
m and 925–1,100m), and a smaller sec-
tion at Tyskgården are included in the
reserves figures. Kvarnberget is yet to
be added, and Boliden is also exploring
to the north of the Gransjön where the
property extends for several kilometres.
Sublevel stoping at
Lappberget
The geological and geotechnical char-
acteristics of significant portions of the
newly-discovered orebodies allow mi-
ning using more productive longhole
methods instead of cut-and-fill. Lapp-
berget ore, for instance, can be 60 m-wide
through considerable vertical distances,
and has proved to be suitable for sub-
level stoping using a system of primary
and secondary stopes progressing up-
wards. Primary stopes are 15 m-wide
and 40 m-high and filled with paste
made from concentrator tailings mixed
with about 5% cement. The 20 m-wide
secondary stopes are filled with devel-
opment muck without cement. High pre-
cision drilling is necessary to get opti-
mum ore recovery and fragmentation.
This mining method can possibly be
used in parts of the Kaspersbo orebody,
if rock quality is high enough. This will
help with cost control, which is crucial
for mining in Sweden. With Lappberget
alone containing 5.46 Mt of the current
reserves, grading over 7% zinc and 2.6%
lead, plus silver and gold, it is no sur-
prise that present development activities
focus on using longhole-based produc-
tion from these orebodies to raise total
metal-in-concentrate output. Presently
eight orebodies are being exploited.
Garpenberg has generated a strategic
plan for 2006–2019 allocating SEK 1
billion for developing Lappberget. The
overall programme includes: increasing
concentrator capacity to 1.2 Mt/y;
designing and building a paste fill pro-
duction/distribution system; and start-
ing longhole drilling. This latter project
involved rill mining in the Tyskgården
orebody, followed by sublevel stoping
in Lappberget.
Rill mining
A special mining method known as rill
mining has been developed for excavating
the Tyskgården orebody. The orebody
is relatively small, and large quantities
of development muck have to be accom-
modated underground as hoisting facili-
ties are used for ore only.
The method can be described as a
modified sublevel stoping with succes-
sive back fill as mining is progressing.
The 10 m-wide cut-off slots are drilled
across the orebody using up-holes and
blasted in one single firing, starting from
the centre. Seven 127 mm holes are left
uncharged to provide sufficient expan-
sion for the remaining 64 mm holes.
After the slot has been opened, 70 de-
grees up-holes fans consisting of eight,
Sublevel stoping layout and mining sequence for Lappberget orebody.
956 Z
996 Z
916 Z
896 Z
Secondary stope:
20 m wide x 40 m high
Rock fill
Note:
How this hole must be designed to just
miss the drift below to break properly
Primary stope:
15 m wide x 40 m high
Paste fill
Mined in
“Central Zone”
Possible
sequence
17.5 m
Drawpoint
spacing
3 m
3 9 4 10 5 11
6
Development and primary stoping layout 1080 level.

Garpenberg, Sweden
approximately 17 m-long, holes are
blasted into the void. Three rows having
a total of 24 holes are blasted simulta-
neously. After mucking out each blast,
new waste is discharged into the stope
forming a 45 degrees rill down into the
drawpoint. As the waste material will
stay quite stable at 45 degrees rill angle,
the risk of ore dilution is negligible.
Output limitations
The total mine output is restricted to
the 1.2-1.3 Mt/y hoisting capacity
available, with a limited amount of
truck ore haulage to surface possible.
And, although flotation capacity has
been improved, concentrator through-
put is now limited to the same sort of
tonnage by grinding mill capacity.
Assuming demand for Garpenberg con-
centrates increases in the near term, it
will be necessary for New Boliden to
decide whether to increase hoisting
capacity.
Developing the now-available reserves
for higher long-term production using ad-
ditional hoisting and processing capacity
might double the amount of investment
initially planned.
New drilling technology
Atlas Copco has supplied drilling equip-
ment to Boliden’s underground mines
for many years. Recently, the company
has worked particularly closely with
Garpenberg on the development of
computer-based technology for more
precise drilling and blasting to enhance
productivity and reduce ore dilution and
operating costs.
Drill pattern for cut off slot.
Refill of waste
Cutoffslot
Approx.15m
Waste
Blasted ore
1.8m8holesineachfanØ70mm
3fansinoneblast
70°
45°
Rill mining in progress
Max
2 m
Approx.15m
One fan
Rill mining in progress.

Garpenberg, Sweden
This joint development process star-
ted with the 1998-1999 ramp extension
at Garpenberg North. The complex geo-
logy results in winding cross sections
of varying width, and ore boundaries
which are difficult to predict by core
drilling. To enable the drifts in the cut
and fill stopes to follow the paths of the
orebodies, accurate production maps
and precise drill rig navigation are es-
sential. Producing drill plans in the
office is relatively easy. However, get-
ting drill plans that match the actual ore
boundaries is a challenge, and frequent-
ly the driller is obliged to improvize
while drilling, which can lead to poor
blasting results.
Drill plan generator
The drill plan generator overcomes the
ore navigation problem by assisting the
operator to create an optimum drill plan
right at the face. In case the generated
drill plan does not match the actual ore
boundaries, the operator can define new
coordinates to correct the situation. To
do this, having aligned the feed to the
laser beam to define the position of the
rig, the operator points the drill feeds
at the four corners of the face, in line
with the geologist’s marks. When all
adjustments have been made, the Rig
Control System RCS will develop the
most efficient round compatible with the
new parameters. The generated drill plan
is automatically entered into the Rocket
Boomer L2 C ABC Regular standard
drilling system, and the operator can
start drilling. While drilling, each com-
pleted hole is logged, and, if the Measure
While Drilling (MWD) option is acti-
vated, the drilling parameters along the
hole are recorded. All of the data is log-
ged on the PC card for off-line processing
in the Tunnel Manager support pro-
gram, and is then transferred to the
mine database. As a result of the Drill
Plan Generator and ABC Regular,
Garpenberg North increased the size
of the production rounds from 400 t
to 600 t, reduced drilling time from 5
to 3 h/round, reducing costs of explo-
sives, scaling and rock support and,
most important, minimizing ore dilu-
tion. Garpenberg now has one Rocket
Boomer L2 C30 rig with COP 3038
rock drills and one Rocket Boomer L2 C
with the COP 1838, as well as the
Rocket Boomer 352S.
Mine navigation
The availability of orebodies at Garpen-
berg suitable for mining with longhole
production drill rigs led to a further
collaboration. Having already transfer-
red RCS technology to the Simba long-
hole drill rigs, Atlas Copco provided
the mine with a Simba M7 C that is
additionally able to use new software
for precision longhole drilling. This
utilizes Garpenberg’s mine coordinate
reference, mapping and planning sy-
stem in a similar way to the software
developed for the Rocket Boomer L2 C
units.
Using a PC card, the Mine Navigation
package can effectively integrate the
Simba RCS with the mine co-ordinate
reference system, allowing the operator
to position the machine at the correct
vertical and horizontal coordinates in
the drilling drift for drilling planned
longhole fans in precisely the intended
place. Using the drill plan supplied by
Microsystem (or, in other mines, the Ore
Manager package) to the Rig Control
System, the operator can drill to the
exact x, y and z positions prescribed
for each hole bottom. Just as the Rocket
Boomers can use the MWD system
while face drilling, so the Simba can
use Quality Log to record drilling
parameters and compare the planned
and actual result, allowing holes to be
re-drilled if necessary.
This new technology will help Gar-
penberg to optimize economy and pro-
ductivity when applying long hole drilling
mining methods. The target for 2007
is to mine about 600,000 t of ore by cut-
and-fill, 300,000 t by sublevel stoping,
150,000 t by rill mining and 150,000 t
by crown pillar removal. Further ahead,
sublevel stoping may contribute 50%
of total mine production. However, at
present this mining method is com-
pletely new to the mining teams at
Garpenberg, and they have just started
the process of getting acquainted with
long hole drilling methods.
Acknowledgements
This article is based upon an original
report by Kyran Casteel. Atlas Copco
is grateful to the mine management at
Garpenberg for their assistance with
site visits, and in particular to Tom
Söderman and Lars Bergkvist for com-
ments and revision.
Z
X
Mine coordinate system
X/Y horizontal
Z vertical
Reference point
(x, y, z) Y
Reference line
Navigation system for downwards longhole production drilling.

Garpenberg, Sweden
Headframe at Garpenberg.

Zinkgruvan, Sweden
Methodology
Until the mid-1980s, upwards cut and
fill was the dominant mining method.
However, when mining began at the 650
m-level in Nygruvan, the first problems
with rock stress occurred, resulting in
the need for increased rock reinforce-
ment.
When mining reached the 566 m-
level, a borehole camera survey revealed
a roof split 6 m above the stopes, caus-
ing abandonment of cut and fill methods
on safety grounds.
Benching methods were introduced,
and have been under constant develop-
ment since, primarily because of high
rock stress. Using benching, no working
place need be developed wider than 7 m.
Over the years, benching has devel-
oped from longitudinal bench and fill.
The mined out bench is backfilled with
hydraulic fill before mining the next
bench above. Vertical pillars in the ore
are left to stabilize the surrounding rock.
Open stoping
Development continued towards sub-
level open stoping, which is a larger
scale stoping method than longitudinal
bench and fill, with improved rock
stress.
Sub-level open stoping as a pro-
duction method worked excellently in
Nygruvan, where the country rock is
of extremely good quality. The ore is
homogeneous, with distinct ore bounda-
ries where dip in the ore is greater than
75 degrees. The open room that is
formed after the stope is mucked has
height measurements of up to 70 m,
width of 15 m, and a length of 50 m.
After mucking is completed, the draw-
points are sealed with bulkheads, and
filled with hydraulic fill.
In the mid-1990s, the Burkland ore-
body was developed. Rock quality and
ore geometry were different compared
to earlier orebodies, and a project was
initiated to utilize a modified sub-level
open stoping method for orebodies with
weaker hanging walls, but retaining the
advantages of the stoping method.
In this method, open stopes have the
approximate dimensions 40 m-high x
50 m-long, and the orebody width up
to 30 m. Pillars up to 10 m-thick are
left between every stope to support the
hanging wall, so some 16% of the ore
is utilized as pillars. After the first stope
Changing systems at Zinkgruvan
Partners in
production
Zinkgruvan Mining, Sweden’s third
largest mining company, is owned
and operated by Lundin Mining
Group. Zinkgruvan Mining produ-
ces zinc concentrate (55% Zn) and
lead concentrate (73% Pb and
l,400 g/t Ag) and ships to smelt-
ers in northern Europe. The mine
has been continuously in produc-
tion since 1857, and ore output
in 2006 was 787,000 t, together
with around 250,000 t from waste
development. Average zinc grades
were high at 10.3%, whereas lead
grades fell to 4.6%, and silver to
93 g/t. For 2007, ore production
is planned at 850,000 t, and a pro-
ject to increase reserves is under-
way.
Zinkgruvan ore reserves total
11.2 million t, containing 9.3%
zinc, 4.3% lead and 107 g/t silver,
equivalent to approximately 15
years of production. Added to
this, discovered in the 1990s, is a
copper mineralization of 3.5 mil-
lion t containing 3.1% copper and
49 g/t silver.
Production is obtained from
open stopes where, following
difficulties with seepage from
hydraulic fill when rock quality
diminished, the mine now uses
paste fill. Rather than deepen
the main hoisting shaft, the main
ramp access was developed be-
low the 800 m level and will bot-
tom out at 1,100 m under present
plans. Key to Zinkgruvan produc-
tion efforts is equipment sup-
plied by Atlas Copco, which in-
cludes four Simba production
drill rigs, three Rocket Boomers
and two Boltec rigs, together
with long-term maintenance and
consumable supply contracts.
Longhole drilling with Simba M4 C in the Burkland stopes.

Zinkgruvan, Sweden
was mined in late-1998, the quality of
the hanging was found to be worse than
expected, with cave-ins, high waste rock
dilution, and difficult backfilling.
Burkland stopes
Earlier, a study of the new copper ore-
body had recommended that longhole
open stoping and paste backfill should
be used when the width of the copper
mineralization reaches up to 40 m. The
results of this study were adapted to
the Burkland orebody, where the 450
section was converted to longhole open
stoping with primary and secondary
stopes. The first two primary stopes
were mined out by October, 2000.
When the primary stopes are extracted,
they are paste filled. The secondary stope,
lying between two paste filled stopes,
can then be mined out and filled with
waste rock, or paste fill with a low ce-
ment content.
The stope design in the upper levels
in Burkland was chosen to facilitate the
change from sub-level open stoping to
longhole open stoping. The levels were
already arranged in 100 m sequences,
so the height of the stopes became 37 m.
Stope width was designed to be about
half the room length used for sublevel
open stoping. The primary stopes were
designed to be 20 m-long, with the sec-
ondary stopes 25 m-long.
The stope hanging walls are cable
reinforced from the ore drive on the
extraction level, and on the upper sub-
level, using 15.7 mm cables with maxi-
mum tensile strength of 265 KN. The
crosscuts are cable reinforced and shot-
creted to secure the footwall brow.
Mine-wide, four longhole rigs are
used for production and cable drilling.
Stopes are drilled downwards from the
orebody drives, and from the crosscuts
in the top sub-level. The benches are
opened on a 600-1,200 mm-diameter
raise bored hole, with an opening slot
along the hanging wall. Blasting is se-
quential, and rock is loaded from the
extraction level below. The transition to
Ergonomically-designed cab on the Simba M4 C drill rig.
45 m
Cable bolts
Drill level
(for below)
Development level
(for above)
Drawpoint level
(shown in plan view)
Cor/slot
A
A
10 m
Rib
pillar
Vertical section through stope looking east
Plan view of typical bottom drawpoint level
Rib
pillar
Rib
pillar
Ore outline
50 m
Robbins opening slots
1
3
7
5
11
2
4
9
10
6
8
Stope drilling and cable bolting. Stoping sequence.

Zinkgruvan, Sweden
longhole open stoping has contributed
to a lower production cost, but the fill
adds expense. However, because the
method does not normally require pil-
lars, no rock is sterilized when mining
the secondary stopes. These savings
offset the fill costs, and 800,000 t is
added to the ore reserves.
CMS surveys on the first two pri-
mary stopes in Bu 450 showed that
drilling and blasting had followed the
ore boundaries according to plan.
Paste fill
Hydraulic fill was introduced to Zink-
gruvan in the early 1970s when the new
mill was built, and was used success-
fully for many years. However, during
the transition to sub-level open stoping,
difficulties arose in sealing the open
stopes when using hydraulic fill. The
bulkheads could not be sealed against
the cracked rock in the draw points, and
there was also seepage through cracked
pillars. Because of the difficulties of
managing the fill, certain stopes have
not been filled, as the risk of fill col-
lapsing is greater than the chances of
a hanging wall collapsing in the open
stopes.
Alternatives that were studied includ-
ed hydraulic fill, with cement for about
50% solidity; paste fill, with cement for
70-76% solidity; and high-density fill,
with cement for greater than 76% solid-
ity. Paste fill with cement was selected
for longhole open stoping with primary
and secondary stopes. Investments
required in the paste plant, and for pipe
installations underground, reached
about 45 million SEK. Golder Paste
Technology, together with Zinkgruvan
personnel, handled the design, construc-
tion and building.
Stope design criteria
The design of stope sizes was based on
the developed levels in the Burkland
ore. The paste fill is horizontally trans-
ported 1.4 km in order to reach these
stopes, so has to be pumpable. The fill
also has to have a minimum strength
of 0.35 Mpa, to handle a free-standing
height of 40 m.
The uni-axial pressure test and pump-
ability test resulted in the specifications
for paste fill in the two orebodies shown
in the table above.
Paste fill is transported to the 350 m-
level of the mine through two boreholes,
Rocket Boomer M2 C developing the sublevels.
Paste fill specifications
Nygruvan Burkland
Primary stope 4 % cement 6 % cement
Secondary stope 1.5 % cement 2 % cement
Slump 150-180 mm 200-250 mm
Waste shaft
Ore shaft
Ventilation
Ramp
Transport drift
Ore drive
Footwall drive
Ore outline
P
P
P
P
P
S
S
S
S
P = Primary
S = Secondary
Plan of stope extraction level.

Zinkgruvan, Sweden
a 165 mm hole for gravitating into Ny-
gruvan, and a 300 mm hole for pumping
under high pressure into Burkland.
The fill is transported through 6 in
steel pipes along the distribution levels,
connected by plastic pipes into the
stopes.
Advantages of longhole open stoping
with paste fill are: improved working
environment for all underground activi-
ties with regards to exposure of open
stopes and backfill; reduced pillar
reservation, leading to increased ore
reserves; increased flexibility, with
more stopes in simultaneous production
and lower grade fluctuation; all tailings
can be used; no bulkheads required;
reduced drainage water; and possibility
of filling abandoned stopes.
Disadvantages are: higher costs than
conventional hydraulic fill; and plugged
fill pipes and drill holes require more
effort.
The long-term focus is directed to-
wards optimization of the water/cement
ratio in the paste fill, with a view to
reducing the amount of cement used.
Lower development
In order to mine below the 800 m level,
the mine uses three Kiruna Electric
trucks for ore and waste haulage to the
main crusher. A Simba M4C longhole
drill rig is used on production, drilling
up to 40 m-long x 76 mm or 89 mm-
diameter blastholes. The machine pro-
duces some 50,000 drillmetres/year,
while an older Simba 1357 drills a simi-
lar number of metres in the 51-64 mm
range. The mine is so impressed with
the stability of the Simba M4C rotation
unit that it has had an old Simba 1354
rebuilt to incorporate the same unit. A
new Simba M7C handles the cable bolt
drilling. The drilling consumables are
supplied by Atlas Copco Secoroc under
contract. The ramp will be driven from
the current 980 m to the 1,100 m level.
An Atlas Copco Rocket Boomer L2 C
is used on ramp and sublevel develop-
ment, where the requirement is for 18
rounds/week on a 2 x 7 h shift basis.
The mine has purchased a second twin-
boom Rocket Boomer, this time an M2 C,
which is the mining version of the
Rocket Boomer L2 C.
Rock reinforcement
The mine installs up to 20,000 resin an-
chored rockbolts each year, and, having
upgraded its production process, found
that bolting became the new bottleneck.
After prolonged testing of the latest
Atlas Copco Boltec LC, they ordered
two units.
Using these machines, the working
environment for the bolting operatives
has improved immeasurably, since the
continuous manual handling of resin
cartridges has been eliminated. The
Boltec LC is a fully mechanized rock-
bolting rig, with computer-based control
system for high productivity and preci-
sion. The Zinkgruvan models feature a
new type of magazine holding 80 resin
cartridges, sufficient for installation of
16 rockbolts. It is equipped with a
stinger, which applies constant pressure
to keep it stable at the hole during the
entire installation process. The operator
can select the number of resin cartridges
to be shot into the hole, for which the
blow capacity is excellent.
The Rig Control System (RCS) fea-
tures an interactive operator control
panel, with full-colour display of the
computer-based drilling system. Auto-
matic functions in the drilling process,
such as auto-collaring and anti-jamming
protection, as well as improved regula-
tion of the rock drill, provide high per-
formance and outstanding drill steel
economy. There is integrated diagnos-
tic and fault location, and a distributed
hydraulic system, with fewer and shorter
hoses for increased availability. Data
transfer is by PC-card, which also
allows service engineers to store opti-
mal drill settings.
The MBU bolting unit on the Boltec
LC features a single feed system, uti-
lizing a cradle indexer at the rear end,
and a robust drill steel support plus
indexer for grouting at the top end. It is
equipped with a low-mounted magazine
for 10 bolts, designed for maximum
Boltec LC installing rockbolts in a development drift.

Zinkgruvan, Sweden
flexibility during drilling and bolting.
The COP 1432 rock drill was, before be-
ing replaced with COP 1132, the short-
est in its class, with modern hydraulic
reflex dampening for high-speed drill-
ing and excellent drill steel economy. It
has separately variable frequency and
impact power, which can be adapted to
certain drill steel/rock combinations.
The BUT 35 HBE heavy-duty boom
is perfect for direct, fast and accurate
positioning between holes, and, at Zink-
gruvan, this has been extended by 700
mm. Large capacity working lights and
a joystick-operated spotlight ensure that
the operator has outstanding visibility.
Profitable collaboration
The Rig Control System (RCS), origi-
nally developed for Boomer rigs, is now
also installed on Simba and Boltec rigs,
so the mine benefits from the common-
ality. Atlas Copco has total responsibility
for all service and maintenance opera-
tions on its equipment at Zinkgruvan,
and has three service engineers sta-
tioned permanently at site. The com-
pany is also under 3-5 year contract for
the supply, maintenance and grinding of
Secoroc rock drilling tools, overseen by
a Secoroc specialist.
From the mine point of view, they be-
lieve they have profited by their collabo-
ration with Atlas Copco, particularly in
the field testing of the new generation
rigs. Early exposure to the capabilities
of these machines has allowed them to
adapt their mining and rockbolting
methods to the new technology, giving
them a head start on the savings to be
achieved. Also, by leaving the long-term
maintenance and supply of rock drilling
tools in the hands of Atlas Copco, they
are free to concentrate on their core
business of mining. Above all, it ena-
bles them to make accurate predictions
of drilling and bolting costs, which will
improve overall cost control.
Acknowledgements
This article is based on a paper written
by Gunnar Nyström. Atlas Copco also
gratefully acknowledges the inputs of
Jonas Södergren, Hans Sjöberg and
Conny Öhman, all of Zinkgruvan
Mining.
Crown pillar
Typical
cable
bolting
∅ 51 mm
drill bit
4.5 m
8-15 m
Production
drilling
∅ 74 mm
drill bit
Drawpoint level
Typical cross section of the orebody looking east.
30m
Opening slot
Opening raise
Cut off raise
Top view
Front view
Primary stope drilling layout.

Experience and Knowledge
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rock drilling solutions. What’s more, the people you work with are
the best – with the ability to listen and to understand the diverse
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It means making customer relations and service a priority.
Through interaction, innovation and a continuous drive to improve
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Kiruna, Sweden
Continuous quest
The Swedish state-owned mining com-
pany LKAB is on a continuous quest
for the most favourable balance possible
in the relationship between ore recov-
ery, waste dilution, overall costs and
productivity. Much of the development
work done here has been carried out in
close cooperation with equipment sup-
pliers, including Atlas Copco.
LKAB's relationship with Atlas Copco
began in the early 1960s, with mecha-
nized drilling equipment which was the
predecessor of today’s automated long-
hole production drilling system.
In 1997, Atlas Copco supplied LKAB
with four Simba W469 drill rigs equip-
ped with a PLC control system. This
technology is now being successively
upgraded with the latest generation
of rigs equipped with a PC-based Rig
Control System RCS, the Simba W6 C
fitted with LKAB's Wassara W100 in-
the-hole hammer.
LKAB operates two large mines
north of the Arctic Circle, where its
Kiruna and Malmberget mines together
supply about 4% of the iron ore require-
ments of the world’s steel industry. With
no sign of a slow down in demand, the
company has ambitious plans for the
future. These include new main haulage
levels at both mines, which this year
alone will require the development of
some 40 km of new drifts.
The modern Simba production drill-
ing rigs have made a clear difference in
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2005
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Nivå m
1045 m Main haulage level
Sea level
Railway to Narvik port
1365 m New haulage level
Exploration drift
1060 m
Ore buffer
pockets
Skip hoisting
Crusher
Skip hoisting
Crusher
Ore beneficiation plant
Mining of the
Kirunavaara orebody
Mining of the Kirunavaara orebody over the last century.
Increasing outputs at LKAB
iron ore mines
Optimum
techniques
For more than 40 years, the miners
of LKAB in the far north of Sweden
have been working to get as close
as possible to the optimum un-
derground mining technique. At
Kiruna, in what is the world's larg-
est underground iron ore opera-
tion, many milestones have been
reached and passed. Now another
is on the horizon as the mine takes
new steps to go deeper and ex-
pand. Sister mine Malmberget is
also expanding output, albeit on
a lesser scale. Key to both is a
collaboration with Atlas Copco
that is providing specialized drill-
ing equipment together with the
means of maintenance.

Kiruna, Sweden
LKAB performance, increasing output
by 40%. In 2007, Kiruna will extract
around 27 million t of crude ore, with a
plan to increase to 30 million t in 2009.
Malmberget’s plan is less ambitious, but
significant, in moving production up
from its 2007 base of 16 million t to 17
million t in 2012.
Optimizing ore recovery
The Kiruna orebody is a single large
slice of magnetite about 4 km-long and
80 m-wide, extending to a depth of 2 km
with a dip of around 60 degrees. Sub-
level caving is used, drilling upward fans
of 115 mm-diameter holes. The method
lends itself to a high degree of automa-
tion, resulting in high productivity.
LKAB is constantly striving to mini-
mize ore losses and waste dilution,
seeking the best combination to achieve
optimum results.
Under investigation are: analysis of
the positive effects of accurate drilling
on ore recovery rates, waste dilution and
fragmentation; the impact of alternative
drill fan configurations and hole burdens
on mucking and operating costs; and
the optimum distance between levels.
All agree on one thing: straight, ac-
curate holes which reach their preplan-
ned target points are vital, because hole
deviation has a negative impact on all
aspects of the production operation.
Thanks to the improving ability to
drill straight holes, LKAB has been
able to gradually increase the spacing
between the sublevels from 12 m in the
mid-60s using compressed air-pow-
ered, tophammer rock drills, to today's
30 m using water powered ITH ham-
mers. This has resulted in controlled
levels of ore losses and waste dilution.
However, the mine wants to raise the
bar even higher, believing there is still
much more that can be done to increase
efficiency, productivity and overall
economy.
Increasing outputs
From their control rooms, the LKAB ope-
rators run several drill rigs out in the pro-
duction areas via remote control. The
fans are drilled forwards, 10 degrees off
vertical, generally with a burden of 3 m,
although a 3.5 m burden is used in some
parts of the Malmberget mine. Pumped
emulsion and Nonel detonators are the
standard explosives.
Kiruna mine is aiming to achieve one
million metres of production drilling in
2007. Malmberget, on the other hand, is
going for 0.6 million metres. But both
will need to increase their capacity in
order to maintain and increase the buffer
between production drilling and loading.
It was in 2005 that LKAB took the
decision to install three Simba W6 C
units which are modified versions of the
Simba L6 C. Two of these are designed
for optimized production drilling at
Kiruna Mine with the Wassara water
hammer.
The third, a Simba W6 C Slot, was
redesigned for optimized up-hole slot
drilling in the Malmberget mine. This
rig has the ability to drill production
holes around the slot, with the added
benefit of drilling parallel rings from the
same set-up with a burden of 500 mm.
The criteria from LKAB were high
productivity, efficiency and accuracy.
The rigs in the Kiruna mine will have
to drill 60 m-long holes in order to meet
future targets.
Such long holes have to be very
straight, and with the new rigs LKAB
has high expectations for both produc-
tion rates and precision, with the flex-
ibility of being able to run the rigs
manually as well as automatically. The
Wassara hammer has the advantage that
it does not leak oil into the environment.
Setting up a Simba W6 C for production drilling.
Simba W6 C drilling upholes at Kiruna mine.

Kiruna, Sweden
For each of the Simba W6 C rigs
LKAB has set targets of 80,000 drill-
metres/year. Since October 2006, the
two drill rigs at Kiruna have achieved
65,000 and just over 70,000 drillme-
tres/year respectively, with an average
monthly performance of 10,000 drill-
metres.
Alternative configurations
The rigs drill alternative configurations
with holes 15-58 m long. The fans are
spaced at three metre intervals, and any
deviation of more than 2% might cause
the fans to overlap. The average pene-
tration rate is 0.65 m/min over the entire
hole, which can be compared to top-
hammer drilling where the penetration
rate drops with hole depth, and the risk
of deviation increases.
All of the rigs have drill tube maga-
zines which are sufficient for drilling the
required hole lengths, thereby eliminat-
ing the need for manual addition of tu-
bes. They are also equipped with a
PC-based Rig Control System (RCS)
specially designed for ITH applications.
The new water pump system reduces
water spillage and lowers the overall
cost. The pump pressure control has
been modified to optimize hammer
efficiency.
With increased automation and re-
duced manning there is a growing need
for remote surveillance. Atlas Copco's
Rig Remote Access (RRA) interface
allows the user to connect the drill rig
to an existing network system via LAN
or WLAN. RRA is used for remote su-
pervision when drilling unmanned in full
fan automation, as well as for transfer-
ring drill plans and log files and hand-
ling messages from the rigs' control
systems.
If manual operation is preferred, the
rig cabin offers a good working environ-
ment with vibration damping and noise
insulation.
The LKAB rigs are working with
ABC Total, the highest level of auto-
mation, facilitating drilling a full fan in
automatic mode with only some initial
steps needed from the operator. Within
the ABC Total package, there is also
the possibility to drill manually or with
one-hole automatics if preferred. The
Groups of ore passes
2
7
11
16
20
25
29
34
38
43
1048 m
Development of 1365 m haulage level at Kiruna.
The Wassara W 100 hammer on the Simba W6 gives good penetration and, as it is water-powered, does not release any oil into the air.

Kiruna, Sweden
automatic systems also enable the rigs
to run unmanned during shift changes,
lunch breaks and night shifts.
Service agreements
Both LKAB mines have full service
agreements with Atlas Copco, who pro-
vide continuous preventive maintenance
for their fleet of 20 rigs. Under the terms
of the agreement, Atlas Copco runs a
thorough check on each rig at the rate of
one per week. The agreement, which is
based on the number of metres drilled,
also includes the supply of all spare
parts. Only genuine Atlas Copco parts
are used on contract maintenance, guar-
anteeing longer service life and greater
availability.
The availability target is 92%, and
penalties are payable on underper-
formance, with bonuses awarded if the
targets are exceeded. LKAB is pleased
with the agreements and the way they
have been designed, feeling they can
let go of the maintenance responsibility
and concentrate on drilling.
Many changes have been introduced
to ensure communication between mine
and manufacturer on a regular basis,
resulting in a mutual approach to prob-
lem solving with a focus on proactive
and preventive maintenance.
One of the most important changes
was to reorganize the service intervals
to better fit in with LKAB schedules.
Another was to move the service centre
for the team of 18 service and mainte-
nance staff from underground to sur-
face.
LKAB confirms that the improve-
ments have had the desired effect, with
more consistent maintenance. Regular
meetings, spontaneous as well as planned,
ensure a more structured approach to
problems. As a result Atlas Copco is
seen by LKAB as safe and reliable.
Acknowledgements
Atlas Copco is grateful to the manage-
ments of Kiruna and Malmberget mines
for their assistance in the production of
this article.
Alternative drilling configurations under consideration by LKAB.
All on the same team: From the left, Robert Wetterborn, Construction Supervisor, Mining Dept. at LKAB, Patrik
Kansa, Atlas Copco Service Manager and Roger Lärkmo, Production Manager, Production Drilling at LKAB.

Kemi, Finland
Introduction
Outokumpu is one of the world’s largest
stainless steel producers, accounting for
about 8% of global stainless slab output,
and a similar share of cold rolled pro-
duction. These are hugely significant
proportions of a market that has risen
by an average of 5.5% per annum over
the last 20 years, and is currently enjoy-
ing 7% growth.
Mainstay of the Outokumpu strategy
is its highly cost-efficient fully integrat-
ed mine-to-mill production chain in the
Kemi-Tornio area of northern Finland.
An ongoing investment programme of
EUR1.1 billion will expand total slab
capacity from 1.75 million t to 2.75 mil-
lion t, and coil rolling capacity from 1.2
million t to 1.9 million t.
Ore reserves at Kemi chrome mine
are abundant, and the efficiency of the
Tornio smelter is enhanced by its prox-
imity to both the mine and harbour
facilities. Mining production has been
progressively switched from surface to
underground, where intensive use is
being made of information technology
to optimize the overall mining and pro-
cessing operation. Underground mining
started in 2003 at 150,000 t/y, and pro-
duction will increase to the planned level
of 1.2 million t/y by 2008.
Reserves
The Kemi deposit is hosted by a 2.4 bil-
lion year old mafic-ultramafic layered
intrusion extending for some 15 km north-
east of the town itself. The chromite-rich
horizon appears 50-200 m above the
bottom of the intrusion, and has an
average dip of 70 degrees northwest.
The main immediate host rock is weak
talc-carbonate, in which the hanging
wall contact is clearly defined. At the
footwall, the chromite and host rock is
inter-layered, and must be mined selec-
tively. However, there is strong granite
some 80 m below the footwall.
The Kemi chrome deposit comprises
11 mineralizations within a 4.5 km-long
zone varying from 5-105 m in width,
with average thickness of 40 m, a min-
eral resource of over 150 million t of
28.6% Cr2O3. Of this, there are 50 mil-
lion t proven reserves underground be-
tween the 500 m level and the bottom of
the open pit. The ore body continues at
depth, probably to 1,000 m, with 750 m
having been reached by the deepest
exploratory hole. The 1.5 km-long x
500 m-wide main pit has a final planned
depth of 220 m.
A two shift/day, five day/week pat-
tern is worked in the mine, from which
about 1.2 million t/y of ore grading
24-26% Cr2O3 is processed continu-
ously by the concentrator. The yield
is 220,000 t/y of 12-100 mm lumpy
concentrate with 35% Cr2O3, and
420,000 t/y metallurgical grade con-
centrate at 45% Cr2O3. Over the years,
more than 30 million t of ore have been
From surface to underground at
Kemi chrome mine
Intelligent mining
The large chromite deposit being
mined by Outokumpu at Kemi,
Finland has a lower than average
Cr2O3 content of about 26%, so
chromite and ferrochrome pro-
duction technology has had to be
continuously upgraded to remain
competitive.
The Intelligent Mine Implemen-
tation Technology Programme of
14 projects achieved real time con-
trol of mine production in precise
coordination with the needs of the
mineral processing plant and the
ferrochrome smelter. The system
utilizes a fast, mine-wide infor-
mation system that can help opti-
mize financial results for the whole
operation. Computerized drilling
with Atlas Copco Rocket Boomers
and Simbas, accurate coring with
Craelius rigs, reliable rock reinfor-
cement with Cabletec and Boltec
rigs with Swellex bolts, and the
dependability and longevity of
Secoroc drilling consumables sup-
port this unique mine strategy. The
result is cost-efficient, integrated
production, on a model which may
form the basis of the next genera-
tion of mining techniques.
A 3D impression of Kemi mine showing the open pit, the underground development and the orebodies.

Kemi, Finland
produced from open pits, resulting in
130 million t in the waste heaps.
Ore grade control
Ore grade control in both the open pit
and the underground mine involves in-
tensive wire line diamond core drilling,
to determine boundaries and qualities
of specific ore types. In addition, all
blast holes in the open pit are sampled.
Technical innovations for ore charac-
terization and quantification include
OMS-logg down hole logging, and auto-
mated image analysis for establishing
grain size distribution.
Basic production data about mineral-
ogical and process histories are logged
for each ore stope on a daily basis, and
this is merged and compared with daily
and blast-specific production histories
from the database.
Each ore blast is treated selectively at
the concentrator, in order to minimize
feed variation and maximize process
stability.
In the concentrator, total chromite
recovery is around 80%, depending on the
proportion of lumpy ore. Metallurgical
grade concentrate contains about 45%
Cr2O3 of 0.2 mm grain size, while up-
graded lumpy ore is about 35% Cr2O3
with 12-100 mm size. The former is pel-
letised at Tornio, and then mixed with
upgraded lumpy ore before smelting to
produce ferrochrome.
Concentrator operation is optimized
by accurate calibration of the feed slurry
analyzers, and control of product quality
from each unit process, both by com-
pensating for changes in feed type, and
measuring product quality on-line.
Manual input can be used, as well as
on-line information.
A Craelius Diamec 264 APC drill rig
carries out 10 km of coring each year.
Drill sections are established every 10
m and downhole survey is standard pro-
cedure, using a Maxibore system. Based
on the drill hole data, a 3D model of the
orebody is created and used as a basis
for production planning. Tying all these
streams of collected data and planning
outputs together requires an extremely
fast communications network, interfac-
ing with a single master database.
Underground infrastructure
The main decline starts at a portal in
the footwall side of the pit, at about 100
m below the rim. The decline is mostly
8 m-wide x 5.5 m-high, to accommo-
date passing vehicles. It descends at 1:7
to a depth of 600 m at the base of the
hoisting shaft, and connects with sev-
eral intermediate sublevels. The decline
is asphalted throughout most of its
length.
There is also a 5,000 cu m repair
shop for open pit equipment at the 115 m
level, and a larger 14,000 cu m work-
shop at the 350 m level for the under-
ground mobile equipment fleet. The
final 23,000 cu m main workshop is at
the 500 m level. The 350 m level work-
shops are enclosed by megadoors, which
keep in the heat so that an ambient 18
degrees C can be maintained. The ser-
vice bay is equipped with a 10 t travel-
ling gantry and 16 m-long inspection
pit. The washing bay is equipped with
two Wallman hydraulically controlled
washing cages, so there is no need for
operatives to climb onto the mobile
equipment.
The main pumping station is located
at the 350 m level, and has pumping
capacity of 2 x 250 cu m/h. The slurry-
type pumps, with mechanical seals,
pump the unsettled mine water to the
surface with a total head of 360 m. Two
other dewatering pumping stations are
located at the 500 m and 580 m levels.
Kemi underground mine – simplified long section.
Atlas Copco Diamec U6 APC at work underground.

Kemi, Finland
The crusher station at the 560 m level
is equipped with a 1,000 t/h Metso
gyratory crusher. This is fed from two
sides by vibrating feeders from separate
8 m-diameter main ore passes from the
500 m level, and from one side by a plate
feeder, to which the ore can be dumped
from the 550 m level. A 40 t travelling
gantry crane services the entire crusher
house. Crushed ore gravitates onto a
conveyor in a tunnel below the crusher
for transport to the shaft loading pock-
ets 500 m away.
Underground production
Trial stopes in three areas accessed
from the 275 m and 300 m levels were
mined to determine the parameters of
the bench cut-and-fill technique to be
used. These had a width of 15 m, and
were 30-40 m-long, with 25,000-30,000
t of ore apiece. Both uphole and down-
hole drilling methods were tested, and
51 mm-diameter downholes selected as
being the safest.
For production purposes, 25 m-high
transverse stopes are laid out, with cable
bolt and mesh support to minimize dilu-
tion. Primary stopes are 15 m-wide, and
secondary stopes 20 m-wide. Cemented
fill, using furnace slag from an iron ore
smelter and fly ash from local power
stations, is placed in the primary stopes,
while the secondary stopes will be back-
filled with mine waste rock. The pri-
mary stopes are being extracted one or
two levels above the secondary stopes.
Mining sublevels with 5 m x 5 m cross
sections are being established at 25 m
vertical intervals, using an Atlas Copco
Rocket Boomer L2 C drill rig equipped
with COP 1838ME rock drills and 5
m-long Secoroc steel and bits. Rounds of
60-80 holes take about 2 hours to drill,
charge and prime. An emulsion charging
truck with elevating platform and Atlas
Copco GA15 compressor provides fast
and efficient explosives delivery. The
footwall granite is very competent, but
lots of rock reinforcement is required
in the weaker host rock, where all drives
are systematically rock bolted and secu-
red with steel fibre reinforced shotcrete.
The planned nominal capacity is 2.7
million t/y of ore, which allows for
increased ferrochrome production at
Tornio when Outokumpu decides to
expand the smelting operation. Budgeted
cost for mine development is EUR70
million.
Rock reinforcement
2.4 m-long Swellex Mn12 bolts are used
for support in ore contact formations.
These are being installed at a rate of
80-120 bolts/shift using an Atlas Copco
Boltec LC rig, which is returning drilling
penetration rates of 3.2 to 4 m/min. The
Boltec LC rig, featuring Atlas Copco
Rig Control System RCS, mounts the
latest Swellex HC1 pump, for bolt infla-
tion at 300 bar pressure, and reports
progress on the operator’s screen.
The HC1 hydraulic pump is robust,
simple, and with low maintenance cost.
Coupled to an intelligent system, it rea-
ches the 300 bar pressure level quickly,
and maintains it for the minimum time
for perfect installation. Combined with
the rig’s RCS system, the pump can
confirm the number of bolts successfully
installed and warn of any problems
Rocket Boomer L2 C is used for sublevel development.
Stoping sequence at Kemi mine.

Kemi, Finland
with inflation. A series of slip-pull tests
carried out throughout the mine pro-
ved the strong anchorage capacity of
Swellex Mn12, both in the orebody and
for the softer talc-carbonate and
mylonite zone.
Cable bolting
Kemi installs some 80 km of cable bolt
each year using its Atlas Copco Cabletec
L unit, which is based on the longhole
production drilling rig Simba M7, with
an added second boom for grouting and
cable insertion. The Rig Control System
enables the operator to pay full attention
to grouting and cable insertion, while
drilling of the next hole after collaring
is performed automatically, including
pulling the rods out of the hole. The
main benefit of the two-boom concept is
to drastically reduce the entire drilling
and bolting cycle time. Also, separat-
ing the drilling and bolting functions
prevents the risk of cement entering the
rock drill, thereby reducing service and
maintenance costs.
Kemi tested the prototype Cabletec L
and eventually purchased the unit after
minor modification proposals. During
the testing period, where most holes
were in the 6 to 11 m range, the rig grou-
ted and installed cables at rates of more
than 40 m/hour. The capacity of the unit,
which is governed by the rate of dril-
ling, provided around 50 per cent extra
productivity compared with alternative
support methods.
The Cabletec L is equipped with a
COP 1838ME hydraulic rock drill using
reduced impact pressure with the R32
drill string system for 51 mm hole
diameter. The machine's cable cassette
has a capacity of 1,700 kg and is easy
to refill, thanks to the fold-out cassette
arm. It features automatic cement
mixing and a silo with a capacity of
1,200 kg of dry cement, which is mixed
according to a pre-programmed for-
mula, resulting in unique quality
assurance for the grouting process.
Bench cut and fill
The current mining method is bench cut
and fill, a type of sub-level stoping with
downhole production drilling, in which
primary stopes are 25 m-high, 15 m-
wide and between 30 and 40 m-long.
Using a Rocket Boomer L2 C rig, the
drifts for the primary stopes are devel-
oped laterally from the footwall through
the ore zone. Then a Simba M6 C pro-
duction rig drills down 51 mm diameter
blastholes in fans 2 m apart. Each stope
yields between 25,000 and 35,000 t of
ore.
Tests showed that drilling upwards
would be about 30 per cent more effi-
cient, but because of safety issues relat-
ed to the poor rock conditions, it was
decided to start with downhole drilling
while getting experience with the rock
and the mining method. Meantime,
Kemi ordered a Simba M7 C rig with
long boom to be delivered in August,
2005. With Simba M6 C and Simba M7 C,
operators are able to cover all kinds of
drilling patterns.
Mining of the 20 m-wide secondary
stopes started in 2005, while sub-level
caving with uphole drilling was tested
at one end of the main pit in 2006.
Secoroc rock drilling tools are used
for production drilling. The previous 64
mm holes over-fragmented the ore, but
a switch to 51 mm resulted in lower spe-
cific charges and better fragmentation,
while retaining the same number of
holes. When developing the secondary
stopes, the mine can go back to 64 mm
drilling if there are problems keeping
the holes open due to the stresses and
rock movements.
Boltec LC installing Swellex Mn12 rockbolts.
Cabletec L installing cable bolts at Kemi.

Kemi, Finland
Kemi is carrying out slot hole drill-
ing with a truck-mounted Simba M4 C
rig. The front part of the rig has been
redesigned to accommodate the Secoroc
COP 84L low volume DTH slothammer,
which is used to drill the 305 mm-
diameter opening hole for the longhole
raises. The blasting holes are drilled
off using a COP 54 with 165 mm bit
with the same tubes. The 20 m raises
are blasted in two 10 m lifts.
Rig Remote Access
The drill rigs at Kemi are integrated
into the Ethernet WLAN communica-
tions network that eventually will cover
the whole mine. Currently, this 1 GB
network, which is based on commer-
cially available equipment, covers the
declines, the workshops and parts of the
production area.
This network infrastructure not only
allows effective underground communi-
cation but also means that all the Atlas
Copco drill rigs equipped with the Rig
Remote Access (RRA) option are logi-
cally integrated into the information
systems in Outokumpu's administrative
organization. The RRA is installed on
the Rocket Boomer and Simba rigs.
The RRA, which consists of a com-
munication server onboard the rig and
a network adapter, integrates with the
mine's network to allow data transfer and
remote monitoring and troubleshoot-
ing. It works as a two-way communica-
tion system, since data can be sent and
received in real time between Atlas
Copco and the mine.
For instance, should one of the drill
rigs encounter a problem, the warning
seen by the operator will also be shown
in the mine office, which can then con-
tact Atlas Copco immediately, enabling
them to enter the rig's electronic system
and diagnose the fault. The main bene-
fits of RRA are: the administrative sy-
stem can be updated automatically with
the latest information with no manual
handling; the rig operator always has
access to the latest production planning;
there is no need to write work reports
after each shift, since all log files are
automatically saved to the planning
department; work orders can be issued
during the shift and directed onto the
specific drill rig instead of being written
before each shift; and fault diagnostics
can be conducted remotely, which al-
lows the service technician to diagnose
the problem and choose the correct spare
parts before travelling to the drill rig.
Acknowledgements
Atlas Copco is grateful to the mine and
concentrator management at Kemi for
assistance in producing this article.
The 350 m-level workshop at Kemi.
Simba M6 C at work in the sublevels at Kemi mine.

Kemi, Finland
Access to the underground operations.

Jelsˇ ava, Slovakia
Producing clinker
The fully mechanized underground mine
at Jelsava, operated by SMZ, feeds high
grade magnesite to on-site conversion
facilities with a capacity of 370,000 t/y
raw clinker. The process includes pri-
mary and secondary crushing, followed
by dense medium separation to produce
a concentrate for thermal treatment in
shaft and rotary kilns. Electromagnetic
separators differentiate magnetic brick-
making clinker from non-magnetic
steelmaking clinker.
SMZ’s raw Jelšava clinker is con-
verted to materials for metallurgical,
ceramic and agricultural use. Annual
production is around 352,000 t, com-
prising 167,000 t steelmaking clinker,
160,000 t of brickmaking clinker, and
25,000 t of basic monolithic refractory
mixes. Overall, 85% of SMZ output is
exported to 28 different countries.
To contain production costs SMZ has
been investing in more cost effective
mining, and plans to replace the rotary
kilns with more efficient twin-shaft
kilns that emit very little dust.
Geology
The Dúbrava-Miková orebody that SMZ
exploits is the largest of 12 significant
magnesite deposits in Slovakia. These
extend from Podrecany in the west to
Bankov, near Košice, in the east and were
all mined for varying periods during the
20th Century. The mineralization is part
of a magnesite belt extending from cen-
tral Austria to the Slovakia-Ukraine bor-
der. Within Slovakia, the deposits occur
mainly in the Slovenské Rudohorie
mountains, and Jelšava is in the deeply
dissected Revűcka highland area of this
range. The magnesite deposit extends
over 325 hectares within a spur of the
Magura hill mass, and the maximum
altitude of this spur is 675 m asl. The
underground mine is accessed laterally
from portals in the sides of the spur,
and mineral moves through the proc-
ess plant downhill from the primary
crusher, which is outside the mine on
the same level as the main haulage.
The magnesite is part of a sedimen-
tary sequence that has been subjected
to tectonic forces and metamorphism,
especially during the Variscan and Al-
pine events. This sequence, underlain by
Map of Slovakia showing Jelsˇava location (Industrial Minerals).
Rocket Boomer M2 C moving towards the faces.
Mining magnesite at Jelšava
Mechanization of
overhand stoping in
thick deposits
As Slovakia moved from central-
ized control in the early 1990s, the
management of Jelsava magne-
site mine faced the accumulated
problems of over-exploitation and
under-mechanization. In the inter-
vening years, the mining method
has been revised, the equipment
inventory renewed, and the out-
put quality improved. Despite the
sometimes difficult economic situ-
ation, accompanied by political
upheavals, the employee-owned
company SMZ that controls the
mining operation is doing well.
Atlas Copco and its local distribu-
tor ISOP have been there to lend a
helping hand, as a result of which
Rocket Boomer drill rigs and Simba
longhole drill rigs have become
Jelšava’s main production tools.

diabase, comprises graphitic slate,
bench-like dolomite, and the dolomite
which hosts the magnesite. Graphitic
slate also overlies the dolomite.
Magnesite formation has been dated
at 320 million years and the mechanism
is thought to have been hydrothermal
alteration of a fine-grained Carboni-
ferous limestone bioherm. The orebody
is estimated to be 4,000 m-long,
1,000 m-wide and 400 m-thick, but is
irregular in shape and contains cavities
often filled with ochre. However, it is
structurally sound, to the extent that it
could be mined with pillar support and
no rock reinforcement. The raw mag-
nesite analyses 36-44% MgO, 48-50%
CO2, 0.1-12% CaO, 0-2.3% SiO2 and
3.2-6% Fe2O3. The specific mineral-
ogy makes Jelšava magnesite a unique
source of ferric magnesium, this being
one reason why it is imported by con-
sumers so far away. SMZ estimates a
reserve sufficient for 150 years’ mining
at the present production rate of 1.2 mil-
lion t/y.
Room and pillar
Around 35% of the ore is mined by the
room and pillar method in blocks which
are up to 100 m-long, 50 m-high and 30
m-wide, with 10 m-wide pillars along
the short and long walls of the chamber,
and a crown pillar at the top. Within
these blocks, it is impossible to avoid
mining some lower grade material, and
this is stored in surface dumps.
Parallel uphole and inclined hole
drilling up to 30 m was initially used
for blasting the chambers, but the mine
later switched to fan drilling in order
to achieve better mining efficiency and
safety.
This method again allows the mining
of long, high blocks of magnesite up to
200 m x 300 m x 60 m, mined in up to
five ascending slices.
The technique provides much greater
stability in the rock mass because, not
only are the rooms lower at 4.8 m to
Idealised section of the mining operations and process plant at SMZ (Industrial Minerals).
1. Ventilation (in) raises or airway raises 2. Ventilation (out) raises or exhaust airway
3. Ore passes (raises 4. Re-fill raises 5. Inner pillar 6. Re-fill
1
2
3
4
4
5
5 6
500 m a.s.
450 m a.s.
400 m a.s.
220 m a.s.
323 m
Dúbrava
Milková
Jedlovec
Sequence of room and pillar mining.
1
2
4
3
5
6
1. Fresh air ventilation raises 2. Exhaust airways 3. Ore passes
4. Re-fill raises 5. Pillars 6. Re-fill
Main Level
1. Crushing 1st level
2. Crushing 2nd level
3. Suspension separator
4. Rotary kiln, shaft kiln
5. Electro-magnetic separation
6. Forwarding department

5.0 m-high, but also the voids are filled,
providing a bench for drilling the next
slice as mining proceeds up each block.
Pillars are 5 m x 5 m at 12 m spacing.
The smaller rooms allow more selective
mining, producing a higher proportion
of processable magnesite, while the 4.4
million t of waste material dumped on
surface during chamber mining can
now be used as fill. The fill rate is up
to 300,000 t/y.
In 1971, a new rail haulage was in-
stalled, equipped with locomotives and
20 t-capacity bottom-dump wagons.
The rail system still handles ore from
the core area of the mine, but it is more
cost effective to use truck haulage from
more peripheral parts.
Overhand stoping
Chamber and pillar mining has created
a huge void within the mine, now total-
ling 13 million cu m, and undercut sec-
tions of the hanging wall have collapsed
in places.
Studies resulted in an overhand stop-
ing method being introduced in some
of the mining blocks above the 323 m
level from 1990 onwards, and this now
accounts for 65% of production.
By 1998, SMZ was looking to increase
production and productivity in the over-
hand stoping blocks. In consultation with
Atlas Copco, the mine trialled a Rocket
Boomer 282 equipped with a COP 1432
rock drill. This rig achieved the expect-
ed performance improvement, and was
bought by SMZ, together with a Rocket
Boomer 281 and a Simba H357, for pre-
cise and rapid pillar recovery. The latter
unit was equipped with a COP 1838 rock
drill. Switching from pneumatic to hy-
draulic drilling using the two Rocket
Boomers increased overhand stoping
magnesite output by a factor of four.
In the overhand stoped sections muck
is loaded by a fleet of three LHDs and
two wheel loaders. The LHDs typically
tram to the ore passes that supply the
rail haulage system, while the wheel
loaders dump into trucks that may go
either to the ore passes or directly to the
primary crusher.
New level development
In 2000-2001 SMZ started to develop a
new mining level at 220 m asl. Whereas
extraction had thus far all been above
the local erosion base level, providing
natural drainage at 287 m asl, this new
level is below the water table. The am-
ount of water to be pumped out is equal
to the amount of ore to be extracted.
For initially driving the access ramp,
and later development, plus some pro-
duction drilling, Atlas Copco offered
SMZ a new Rocket Boomer M2 C twin-
boom rig, and helped train six Simba
operators to use it.
Work on the ramp and some lateral
development started in 2001 and was
scheduled to take 3-4 years. The Rocket
Boomer M2 C normally works either
one or two of the mine’s three eight-
hour shifts on the ramp, but also works
on production. The new level will be
worked in 10 m-high slices, improving
geotechnical conditions and saving on
primary development costs. However,
although many blocks of high quality
magnesite are directly accessible using
overhand stoping from the new level,
Overhand stoping room and pillar system at SMZ.
Open stope
Pillar with loading crosscut
and transport drifts
Front
pillarPillar
between
stopes
Rocket Boomer 281 drilling a crosscut entry.
boundary
pillar

some ore is located between access levels,
some is distant from the core facili-
ties, and some occurs as layers too thin
for overhand stoping. Extraction tech-
nology for all these various sources
will require new drilling, loading and
hauling equipment.
Although the new mining level is be-
low the rail haulage, and ore will prob-
ably be delivered directly to the primary
crusher, SMZ expects the rail system to
remain in use for another 10 years.
Grade improvement
Secoroc equipment supplied through
ISOP is used for the Atlas Copco rigs
at Jelšava. Despite the very abrasive
nature of the magnesite, bit life ranges
from 600 m to 1,500 m. The three
Rocket Boomers use 51 mm bits, and
the Simba H357 drills with 64-65 mm
bits. The mine does 80% of its blasting
with ANFO, and uses plastic explosive
for wet holes.
Of the annual mine production of
1.2 million t, around 1.16 million t is
magnesite, and concentrate output is
approximately 700,000 t. Back in 2001,
chamber and pillar mining supplied
430,000 t, overhand stoping 705,000
t and development 28,000 t. By 2002,
70% of drill/blast production came
from overhand stoping with the Rocket
Boomers, 20% from pneumatic drilling
in chamber and pillar sections, and 10%
from pillar recovery with the Simba
H357. The improvement in average
grade achieved by the more selective over-
hand stoping with hydraulic drills has
increased the output of clinker, despite
lower gross output.
Atlas Copco
representation
Atlas Copco has a Customer Center in
Prague, serving the Czech Republic and
adjacent countries. In 1992 ISOP, based
at Zvolen in the centre of the country,
was appointed as its sole distributor in
Slovakia. The Rocket Boomer 282
provided for trials in 1998 was the first
two boom hydraulic rig supplied to
a Slovakian mine, and the Rocket
Boomer M2 C was also a first.
Including the units at SMZ, ISOP
presently supports nine Atlas Copco
underground drill rigs in mines. Other
customers include Siderit, which has
two Boomer H104 drill rigs and several
Atlas Copco hydraulic breakers work-
ing at its iron-manganese ore mine at
Nižná Slaná, not far from Jelšava. ISOP
modified these Boomer H104 rigs at
the workshop in Zvolen so they could
work as longhole drilling rigs. Siderit
delivers ore to the US Steel plant in
Košice, and to the Novy Huta works at
Ostrava in the Czech Republic.
There are also six Atlas Copco sur-
face drilling rigs in the country, five of
which are DTH machines and the sixth
a Coprod-fitted hydraulic rig. This latter
machine yields 500,000 t/y limestone
for supply to US Steel Košice.
Acknowledgements
ment of SMZ for its assistance with the
production of this article.
Geological section of Dúbrava Massif (Industrial Minerals).
Graphitic slate
Magnesite
Dolomite
Bench-like dolomite
Diabase
Ochre

Kure, Turkey
Access
The vehicle access adit is horizontal,
and connects with the spiral ramp
developed in the footwall of the
orebody down to the sump level. The
orebody, which dips at between 45 and
60 degrees, is accessed from the ramp,
along levels spaced at 12 m vertical
intervals.
The 20 sq m oval-plan spiral ramp
was driven at 5-7 degrees from 932 m
level to 792 m level by hand between
1998 and 2000 using Atlas Copco BBC
16W pneumatic rock drills with jack-
legs. This work was carried out under
contract by STFA tunnelling division.
Average advance was 120 m/month.
The top half of each round was drilled
from the levelled muckpile. The total
development carried out prior to produc-
tion was 1,954 m of ramp drivage, 815 m
of shaft sinking, and 3,331 m of other
development.
The sump at the base of the mine
has 2,560 cu m capacity, and there is a
natural water make of 12 lit/sec. Two
vertical shafts to surface and one sublevel
shaft facilitate ventilation. The exhaust
shaft is equipped with a cover, which
can be raised in winter to induce natural
air movement.
View of Asikoy open pit mining operation.
All change for Asikoy copper mine
Moving ore
production
underground
Copper has been mined for many
years at the Asikoy open pit,
located in Kure county, some
60‑km north of Kastamonu in the
western part of Turkey’s Black
Sea Region. Kure itself is 25 km
from the Black Sea coast, and 300
km from Ankara. A major open
pit operation was established in
the mid-sixties, and production
continues to this day. However,
reserves were diminishing, and,
with the available orebody exten-
sions at depth, a plan for under-
ground mining was evolved. This
required excavation of a conveyor
adit to transport rock from under-
ground to the existing mill, and
a vehicle access adit, together
with a spiral ramp to the base
of the known deposit. Shafts for
backfill and ventilation were also
needed. Production commenced
in 2001, when STFA Construction
and STFA Tunnelling Corporation
Joint Venture took over the under-
ground mining operation as con-
tractor, using a fleet of Atlas
Copco equipment which includes
production and development drill
rigs, loaders, and trucks. Monthly
ore production is around 45,000 t
at average grade 2% Cu, with cut-
off grade of 0.5%.
Portal entrance to Asikoy underground mine.

Kure, Turkey
Development
An Atlas Copco Rocket Boomer 282
equipped with COP 1838ME rock drills
is used to develop the ore and waste
drifts.
The Rocket Boomer has one extend-
ing boom to facilitate drilling off the first
rounds in strike drifts at right angles.
Drill hole diameter is 45 mm,
and hole length 3.5 m. The mine has
conducted trials of bits from differ-
ent manufacturers, and has settled
on Secoroc as the most cost-effec-
tive. Around 250 m/month of drivage
is required to keep pace with the
stopes, all of which are mined on the
retreat.
Most development is within the com-
petent footwall rock mass. The orebody
exhibits different rock mass character-
istics. Ground support is by shotcrete,
bolting with mesh, mesh reinforced
shotcrete, standard Swellex in 2.4 m
and 3.3 m lengths, and cement grouted
bolts in 3 m, 4 m and 6 m lengths.
Two manually-controlled Atlas Copco
Scooptram ST6C loaders are used for
mucking development faces.
The Rocket Boomer 282 handles all
rockbolt drilling, with 37 mm holes for
Swellex and 64 mm holes for grouted
rebar. The mine is working with Atlas
Copco to increase the use of Swellex,
because of its better controllability.
Production
The mining method is longhole bench
stoping with post backfill. The ore is
developed by driving strike access drifts
with cross sectional area of 21.68 sq
Scooptram ST6C, one of three at Asikoy.
Line-up of Atlas Copco equipment at Asikoy mine.

Kure, Turkey
m along the footwall contact, or in the
centre of the orebody. Stope preparation
is carried out by driving 7 m-wide x
4.5 m-high sill drifts across the strike,
to the hangingwall or footwall. These
drifts vary in length, depending on the
thickness of the orebody.
An Atlas Copco Simba H1254 with
top hammer is used for stope drilling.
Blast holes with a diameter of 76 mm
are drilled downwards on several pat-
terns, according to ore and stope type.
The mine prefers downhole drilling as
the most practical for their patterns,
while reducing the safety risk.
At the end of the sill drifts, a 1.5 m
x 1.5 m drop raise is opened by long-
hole blasting, and this is widened out to
create a free breaking face. Thereafter,
the bench between the sill drifts is
blasted towards the open slot one or two
rows at a time. The main blasting agent
is ANFO, which may be diluted with
polystyrene beads for the profile holes,
with Powergel primers and Nonel initia-
tion. The ore is mucked from the lower
sill drift using a remote controlled Atlas
Copco Scooptram ST6C. After complet-
ing the extraction of the ore between the
sill drifts, the open stope is backfilled
to the floor level of the upper sill drift.
Once two adjacent primary stopes are
backfilled, the primary pillar can be
mined as a secondary stope.
The production stopes can be up to
60-70 m-long, but average around 30 m-
long. Currently, 8 m is left between
Production drilling with Simba H1254.
Production flow from orebody to surface.
Stoping sequence at Asikoy.
Belt conveyor
Surface
Sill drift development
Muckpile
Stoping
Flexowell
Ore pass
Ore
Grizzly
Crusher
Cemented backfill
Development Production drilling
Blasting and mucking
Filling
HW
HW HW
slot
HW
Belt conveyor
Feeder

Kure, Turkey
sublevels, and the extraction drives are
4.5 m-high. The latest stope, which lies
between 894 m and 912 m levels, has a
height of 12 m, and this larger dimen-
sion will be increasingly used.
Rock handling
The 2.5 m-diameter main orepasses are
also longhole drilled using the Rocket
Boomer 282, or hand drilled. An ore-
pass system to the 804 level feeds the
underground crusher. Crushed ore sized
at –10 cm travels along a conveyor belt
to a feeder, and into a Flexowell verti-
cal conveyor belt system at 792 level.
A trunk conveyor at average grade of 8
degrees transfers the ore to the surface
primary crusher.
There are four vertical shafts for
backfilling at Asikoy, with three sub-
vertical shafts.
Two types of fill are used for backfill-
ing. These are cemented rock fill (CRF)
and uncemented waste fill (WF). CRF,
with a cement content of 5% by weight,
is used for backfilling of primary stopes.
Secondary stopes are waste filled.
Minetruck MT2000 trucks are used for
both types of backfilling.
SFTA has a ten-year contract
to produce 30,000 t/month of ore
grading 2% copper at a fixed price per
tonne, although 414,000 t was produced
over the last year. The ore is concen-
trated to 17% at site, and is trucked to
the port of Inebolu, some 25 km away,
from where it is shipped to a smelter
located in Samsun, along the Black Sea
coast, and to export markets.
Training
This is the first mining operation where
SFTA has been involved and, being the
only Turkish-operated mechanized
mine, the company takes education
and training very seriously. Atlas
Copco undertook the training of the
mine instructors, and SFTA has car-
ried on, giving every man on the mine
specific education, each with a course
every three months. The average age of
operators is around 30, and most have
been with the group for many years.
There are 140 men on the mine. In total,
thirteen engineers have been employed
for production and engineering. Atlas
Copco has a maintenance contract for
its equipment at the mine, and provides
a workshop container manned by a
fitter.
Acknowledgements
Atlas Copco is grateful to the man-
agement of Asikoy copper mine for
the opportunity to visit the project.
Particular thanks are due to Kenan
Ozpulat, project manager, and Serkan
Yuksel, chief mine engineer, for their
assistance at site and in reading draft.
Rocket Boomer 282 on surface. Unique Flexowell vertical conveyor installation.
Minetruck MT2000 discharges cemented backfill into a primary stope.

El Soldado, Chile
History
The El Soldado and Los Bronces copper
mines and the Chagres smelter, all lo-
cated in Chile, are operated by Compañía
Minera Disputada de las Condes.
In addition to its record as a success-
ful mining company, Disputada's oper-
ations achieved recognition in 1999
when it became the first industrial
company to receive Chile’s National
Environment Award, recognizing its
leadership in environmental practices
and its high standards in environmental
management.
Disputada produces around 250,000 t/
year of copper. When, in 2002, Anglo
American plc agreed to purchase Dis-
putada from Exxon Mobil, it substan-
tially enhanced the quality of its base
metals portfolio, in addition to offering
significant synergies with its other
Chilean copper operations, the Doña
Inés de Collahuasi and Mantos Blancos
mines.
El Soldado mine is located 132 km
northwest of Santiago, on the western
slopes of the Coastal range, at about
830 m asl. El Soldado produces around
64,000 t copper in concentrate and
5,000 t copper cathode, and its reserves
are estimated to be 115 million t grad-
ing 1.0% copper.
The total workforce of El Soldado is
under 280 people, of which one third
are employed in the underground mine.
Of these, 24 technicians are employed
in maintenance. The mine operates
Monday to Friday in three shifts of 8 h.
Mining at El Soldado started in 1842.
Since 1978, when Exxon Minerals ac-
quired the operation, about 70 million t
of ore containing 1.8% copper have
been mined by the underground sub-
level open stoping method. In 1989, the
El Morro open pit commenced produc-
tion to increase output to the present
18,000 t/day. Today, the underground
mine provides less than 30% of the
Atlas Copco ROC L8 crawlers at El Soldado open pit.
El Soldado location in central Chile.
SOUTH AMERICASOUTH AMERICA
CHILE
71° 70°
33°
34°
SANTIAGO
VALPARAISO
QUILLOTA
LOS ANDES
LOS BRONCES
EL TENIENTE
EL SOLDADO
SAN ANTONIO
RANCAGUA
CHAGRES
ARGENTINA
El Soldado's deposites
Mining challenge at El Soldado
Integrated operation
El Soldado is a tightly integrated
operation consisting of an under-
ground and open pit copper mine,
a concentrator and an oxide plant.
In order to increase production
underground, El Soldado intro-
duced a variation to its standard
sublevel open stoping mining
method in 1983. Six years later,
the open pit section of the mine
was started, posing an additional
complication for the geotech-
nical and mine design teams.
These days, the engineers enjoy
the challenge of an underground
mine, which features a com-
plex layout and problematic rock
conditions with numerous open
cavities, irregular orebodies of
variable dimensions and in situ
stresses that vary in magnitude as
well as in orientation. Extraction
of the reserves must also follow a
sequence that minimizes impacts
on the overlying surface opera-
tions. A committed user of Atlas
Copco drill rigs, the mine depends
upon Rocket Boomer M2 Cs for
development and Simba M6 Cs
for production, all featuring a high
level of computerization.
SOUTH AMERICASOUTH AMERICA
CHILE
71° 70°
33°
34°
SANTIAGO
VALPARAISO
QUILLOTA
LOS ANDES
LOS BRONCES
EL TENIENTE
EL SOLDADO
SAN ANTONIO
RANCAGUA
CHAGRES
ARGENTINA
El Soldado's depositesEl Soldado deposits

El Soldado, Chile
total concentrator feed, but rather more
of the contained copper.
The sulphide plant's current capac-
ity is 6.5 million t/year, of which the
underground mine supplied 2 million t
in 2006. This is expected to decrease to
1.6 million t in 2007 as open pit output
increases.
Problematical geology
The El Soldado deposit is located in the
Lower Cretaceous Lo Prado formation,
and is thought to be of epigenetic origin.
The main host rocks are trachytes, fol-
lowed in importance by andesites and
tuffs. Copper mineralization occurs as
numerous isolated orebodies, with a
strong structural control, located through-
out an area 1,800 m-long by 800 m-
wide. The lateral limits of the orebodies
are characterized by abrupt variations
in the copper grade. The transition from
high-grade mineralization of 1.2%
to 2% Cu to low grade areas of 0.5%
El Soldado underground mining schematic overview.
Development
Extraction level
Simba
drilling
Transport level
Ore-pass
DTH Drilling
Raise
Boomer drilling
5½ Simba
DTH drilling
2½Simba
radial drilling
Scooptram
loading
Section of El Soldado mine and plant process.

El Soldado, Chile
to 1.2% Cu takes place within a few
metres. Orebodies typically exhibit an
outer pyrite-rich halo, followed inwards
by an abundant chalcopyrite and bor-
nite core, with minor chalcocite and
hematite. The main gangue minerals
are calcite, quartz, chlorite, epidote
and albite.
The orebodies are of tabular shape,
with dimensions that vary from 100 to
200 m in length, 30 to 150 m in width,
and 80 to 350 m in height. The ground
conditions are classified as competent,
with an intact rock strength greater than
200 Mpa, in a moderate stress regime
ranging from 15 to 30 Mpa. These geo-
technical conditions facilitate the devel-
opment of large open cavities, normally
as large as the orebodies, with dimen-
sions from 40 to 90 m width, 50 to 290
m length, and up to 300 m height.
The nature of the major structures,
and the inherent condition of the rock
mass, play a critical role in determin-
ing the extent of any likely instability
surrounding excavations at El Soldado
mine. Seven main fault systems, and a
system of bed contacts, have been de-
fined within the ore deposit limits as
being significant in geotechnical terms.
The induced state of stress after excava-
tion is a significant mine design crite-
ria, and a monitoring objective. In an
attempt to obtain information on the in-
situ stress in critical areas of the mine,
measurements have been carried out.
Mine stability
Mine stability is a matter of prime im-
portance in the planning process, particu-
larly as the El Morro open pit is situated
immediately above the underground
mine. An integral mine plan is there-
fore required, in which the sequence
of extraction, both in the open pit and
underground, needs to satisfy safety
and efficiency criteria. In particular,
the design and extraction sequence of
underground stopes have to be managed
in such a way that they do not affect
the open pit operations, and minimize
disturbance to unmined areas, enabling
maximum resource recovery. This has
to be balanced with the need to main-
tain high-grade feed, and the selectivity
that comes with underground mining.
There has been a large amount of de-
velopment in the underground mine,
creating a large number of stopes, and
a complex layout.
Because of all the aspects that need
to be taken into account before mining
can start, extensive geotechnical moni-
toring is applied to rock conditions, to
detect and identify failures and insta-
bilities, to collect data for mine plan-
ning and stope design, and for ongoing
assessment of mine stability. Over the
longer term, the collected data provides
control points to update the geotechni-
cal database, and to verify the assump-
tions made in the design.
Underground layout
The access points to the orebodies are
located on the slope of the Chilean coa-
stal range hosting the mine, several
Rocket Boomer M2 C underground .
Extraction level layout.
= 1.5 m
10.0 m
40-50o
40-50
o
40-50o
40-50
o
2.5 x 2.5 m
Shaft
Shaft
Shaft
2.5 x 2.5 m
+
++
++
+
++
+ + +
+ + +
+ + +
E
B
Shaft
17to22m
18.0 to 20.0 m
Max 15.0 m
10.0 m 17 to 22 m
17 to 22 m
17 to 22 m
10.0 m
18.0 to 20.0 m
18.0 to 20.0 m
50.0m
Max.transportdistance
Max.transportdistance
150.0m
150.0m
Ventilation
shaft
Ventilation
shaft
Ventilation
shaft
Max 15.0 m
18.0 to 20.0 m
Max15.0m
Max15.0m
Max15.0m
OP
OP
Extraction level layout
Surface workshop at El Soldado.

El Soldado, Chile
hundred metres above the valley floor.
Today, the main entry is located at -100
level (730 m asl) and the haulage level is
at 300 m below datum (530 m asl). The
mine has been developed by a network
of sublevels, providing access to the
tops and bottoms of the mining areas.
Sublevels are linked by ramps, with a
maximum slope of 15%. Ore is loaded
directly into ore passes with an overall
capacity of 10,000 to 30,000 t, which
connect sub levels with the haulage
level. This ore is transported to a crush-
er located on surface, near the concen-
trator, using 50 t-capacity, highway-type
trucks. Some ore is mined below the main
haulage level, and this material is trans-
ported directly to the surface crusher
using trucks and ramps.
Historically, the massive, but irregular,
orebodies and the competent ground
conditions made sublevel open stoping
the preferred mining method. However,
in 1983, fully mechanized sublevel and
large-diameter blast hole open stope
(SBOS) was introduced as a variation
of the standard method, enabling an
increase in production rates. Nominal
stope dimensions are 30 to 60 m-
wide, 50 to 100 m-long, and up to 100
m-high, though large orebodies are
divided into several units, leaving rib
and crown pillars as temporary sup-
port structures. Rib pillars are 30 to 50 m-
wide, and crown pillars 25 to 40 m- thick.
The stopes are mined progressively down-
wards by a traditional SBOS method,
and are left unfilled. Pillars are subse-
quently recovered by a mass blast tech-
nique, and are sometimes designed
to break more than 1 million t of ore
each.
The rock is very competent, and the
stope cavities can be left open, sometimes
standing for 5 or 10 years, depending
on the sector and the rock structure.
Smaller stope cavities normally have
stable geometries, with less than 5%
dilution from back extension or wall
failure. However, three large open sto-
pes, the Santa Clara, California and
Valdivia Sur stopes, have experienced
controlled structural caving, filling the
existing void and breaking through to
the surface. If it is decided to fill a stope,
then waste rock from development is
used.
Production stopes
Production block access is provided by
developing sublevels, with a pattern of
5.0 m x 3.7 m LHD drawpoints at the
base of the stope. Block undercutting is
accomplished with a fan pattern of 60 to
75 mm-diameter holes up to 25 m-long
loaded with ANFO and HE boosters.
Slots are made by enlarging a 2.5 x 2.5
m blast hole slot raise, at one end, or in
the middle, of the stope. Blast holes of
165 mm-diameter and up to 80 m-long
are drilled with an underhand pattern.
Blast size and blasting sequence is
defined for each stope, according to
major structural features and the prox-
imity of existing cavities. Dilution con-
trol is improved, and blast hole losses
avoided, by carefully considering the
particular geometries created by the in-
tersection of major discontinuities and
the free faces of the planned excavation.
Often, faults present geometries which
generate wedges that can slide into the
cavity, affecting fragmentation and gen-
erating oversize rock at drawpoints. The
presence of cavities, or simultaneous
mining in nearby locations, also impose
restrictions in the mining sequence and
size of blast.
Production ore from stopes is loaded
out with 10 cu yd LHDs. One-way dis-
tances of 100 to 150 m are maintained
to orepass tips, which are not equipped
with grizzlies as oversize rock is drilled
and blasted in place at the drawpoints.
Orepasses terminate in hydraulically-
controlled chutes at the –300 haulage
level, where the 50 t trucks are loaded
with run-of-mine ore or development
waste.
A square pattern of 1.90 m x 1.7 m
split set bolts, 2.05 m-long, in combina-
tion with wire mesh, is used to maintain
working areas free of rock fall, and to
protect personnel and equipment. This
approach to ground control is not in-
tended for heavy rock loads or massive
stress-induced instabilities, though
is adequate for local support. Where
needed, cable bolting is used to sup-
port unfavourable geometries, such as
large wedges or low dip bedding layers,
Uphole production drilling pattern.
Downhole production drilling pattern.
Parallel hole drilling
45°
45°
A
C
C´
B
A´
adp 450
Nonel
Radial hole drilling
50 to 75 m
50 to 75 m

El Soldado, Chile
and also to support drawpoints and ore
passes where the rock conditions have
changed dramatically. Occasionally,
cable bolts are used to minimize or pre-
vent caving in the sublevel stopes.
Development headings average 18.5
sq m cross section, in which the intro-
duction of the Rocket Boomer M2 Cs
has increased the incremental advance
from 3.9 to 4.2 m/round. The number
of holes/round has meanwhile been de-
creased by changing from 45 mm to 51
mm-diameter bits and a 5 in cut hole.
Large-diameter blast hole open stop-
ing has worked well at El Soldado. The
mine drills up to 53,000 m/year using
DTH, and 32,000 m/year with topham-
mer drilling. The current method allows
the exploitation of larger units, reducing
preparation costs and improving pro-
ductivity costs. Another advantage of
the method is that it is selective, allow-
ing extraction of only the mineral. The
current cost distribution is: development
32%; service and other 28%; drilling
and blasting 17%; extraction 12%; and
transport 11%.
Equipment maintenance
El Soldado has been through a phase
of equipment replacement. Two of the
three Atlas Copco Boomer H127s
equipped with COP 1032 rock drills have
been replaced by new Rocket Boomer
M2 C units featuring Advanced Boom
Control (ABC) system. These work al-
ongside the remaining Boomer H127
unit drilling 43 mm holes. The old ma-
chines have been rebuilt, one as a secon-
dary drill rig, and the other as a scaler.
For production, El Soldado employs
three Atlas Copco Simba 264 rigs equip-
ped with the COP 64 DTH rock drill
for 5.5 in holes. There are also an Atlas
Copco Simba H221 and a Simba H252,
both used for radial drilling of DTH
holes ranging between 65-75 mm. The
Simba H252 drills the 75 mm-diameter
upholes for the undercut.
The Simba 264 machines are being
replaced by the new generation Simba
M6 C DTH drill rigs, which along with
the Rocket Boomer M2 C units, feature
the ABC Regular, which will be up-
graded to ABC Total in due course.
El Soldado obtains 20% to 30% more
drilling capacity per hour with the new
Simba M6 C machines, on account of
mechanized tube handling and better
control of drilling parameters.
The robust design offers better utili-
zation and lower maitenance. Three
PT-61 ANFO chargers, built on Atlas
Copco DC carriers in co-operation with
Dyno Nobel, are used for both face and
long hole charging. A fourth unit, a
Rocmec DC 11 built on an Atlas Copco
carrier, is equipped with an Atlas Copco
GA 11 compressor and an ANOL CC
type of charging vessel.
For loading and transportation, three
Atlas Copco Scooptram ST8B loaders
are employed. The mine also has three
13 cu yd Scooptram ST1810 loaders
equipped with monitoring systems which
are employed on waste haulage.
Rock reinforcement is carried out
with an Atlas Copco Boltec H335 bolting
machine.
El Soldado has installed a computer-
based system to monitor the condition of
its mobile equipment. The underground
leaky feeder communication system is
linked to the loaders and drill rigs.
Both the open pit and the under-
ground areas have equipment mainte-
nance workshops. A preventive mainte-
nance workshop located on the surface
further serves the underground area,
and field maintenance is carried out on
the Simbas.
Outlook
El Soldado's main objective is to con-
tinue with its tradition of excellence in
safety and cost competitiveness. The
underground mine production is being
reduced as open pit output increases,
and variants of the exploitation method
will be introduced to recover minor
volume reserves using automated radial
drilling to over 40 m depth.
El Soldado's mining plan is intrinsi-
cally linked to its geotechnical and geo-
metric conditions, and so improvements
to the monitoring and data-collection
systems, in order to obtain more precise
geotechnical engineering, are constantly
being studied.
Acknowledgements
This article is based on interviews with
Nelson Torres, Mine Superintendent at
El Soldado, and extracts from the fol-
lowing paper: Contador N and Glavic
M, Sublevel Open Stoping at El Soldado
Mine: A Geomechanical Challenge.
Simba M6 C drilling radial holes.

Fax: +46-(0)19 6707393
www.atlascopco.com
A winning combination
The Rocket Boomer E-series. A new face drilling rig that
features the super-fast, prize-winning COP 3038 rock drill. It
also introduces the BUT 45, a superb new boom that reduces
hole deviation, provides extra large coverage area and slashes
positioning time between holes by 50%. The result?
A winning combination that significantly cuts tunnelling
costs and leads to real operational economy.

El Teniente, Chile
Largest copper producer
Owned by the Chilean state, Codelco
is the world’s largest copper producer.
It produces more than 1.5 million met-
ric fine tonnes (mft) of copper/year,
representing 16% of western world pro-
duction. In addition, Codelco is the world’s
second largest molybdenum producer,
with an output of around 25,000 t/y. The
corporation's other competitive strengths
are its cost efficiency of around 40 US
cents/pound and its reserves, which com-
prise about 21% of the world's total, and
are sufficient for more than 70 years of
mining at current production levels.
Codelco operates five mining divi-
sions at Chuquicamata, Radomiro Tomic,
Salvador, Andina and El Teniente, and
a service division located at Talleres
Rancagua. It also participates in other
mines, including El Abra, and also
has several joint ventures involved in
geological exploration and different
associations in new business.
The company’s vision of the future
aims to consolidate its leadership of the
world copper industry in terms of com-
petitiveness and operating excellence,
thus reinforcing its position in the global
economy. In line with this, Codelco set
itself the goal of doubling its value to
some US$18 billion by 2006, through
higher productivity, market develop-
ment and synergies. Achieving this de-
pended, amongst other factors, on the
successful and opportune implementa-
tion of the US$4.3 billion investment
contemplated in the company six-year
strategic plan.
El Teniente
El Teniente is the world’s largest under-
ground mine, with over 2,400 km of
development to date. The mine is loca-
ted at 2,200 m asl, some 80 km south of
the capital city of Santiago. The total
geological resource at El Teniente above
1,720 m asl is over 10 billion t at 0.65%
copper, and the mining reserves above
1,980 m asl and 0.6% copper cut-off
grade are over 3 billion t at 1.0% cop-
per. El Teniente produces anodes, re-
fined copper, electro-won cathodes and
molybdenum concentrate, all of which
is shipped out through the Port of San
Antonio.
Currently, El Teniente Division em-
ploys 5,219 workers, a decrease of 22%
from the 6,652 it employed in 1996.
During the same period, the total acci-
dent rate was reduced over 50%, while
the cost of production was reduced by
more than 10 US cents/pound. In terms
of productivity, each employee currently
achieves 71 t/y of copper, an increase of
25% since 1996.
History
According to legend, El Teniente was
discovered by a fugitive Spanish official
Isometric representation of El Teniente mining sectors.
Pioneering mass caving at
El Teniente
Mining in primary
rock
One of the five mining divisions of
the Corporación Nacional del Cobre
de Chile, Codelco, El Teniente is an
integrated copper operation com-
prising mine, concentrator and
smelter installations. Faced with
the depletion of its reserves of
high-grade secondary mineraliza-
tion, the division has completed
the change to mining in primary
rock. The early years were trauma-
tic, with major geotechnical prob-
lems including a series of fatal
rockbursts and the collapse of
significant areas of the production
levels. However, El Teniente rose
to the challenge and, following
an extended period of study and
trial mining, is successfully using a
variation of the Panel Caving me-
thod in the new Esmeralda Sector.
This method is now being applied
to future development plans for
the New Mine Level project, which
starts production in 2014.

El Teniente, Chile
in the 1800s. Exploitation first began in
1819, when the highest-grade minerals,
from what became the Fortuna sector,
were mined manually and transported on
animals to the coast. In 1904, William
Braden, an American engineer, founded
the first El Teniente company, Braden
Copper Company, and built a road for
carts and a concentration plant.
In 1916, Braden Copper became a sub-
sidiary of the Kennecott Corporation,
which was able to supply the funds nec-
essary to expand the mine. Kennecott
operated El Teniente until 1971. In April,
1967 the Chilean Government acquired
a 51% interest in the property, and foun-
ded the Sociedad Minera El Teniente.
Following this agreement, major mine
expansion was undertaken, and a new
concentration plant was built in Colón,
which increased total production capac-
ity to 63,000 t/day. Full nationalization
followed in 1971, and El Teniente mine
became a fully state-owned company.
In 1976 Codelco was formed, and El
Teniente became part of it.
Reserves
In total, the El Teniente orebody meas-
ures 2.8 km-long, 1.9 km-wide, and 1.8
km-deep. Schematically, the deposit is
formed around a central, barren, brec-
cia pipe of 1.0 to 1.2 km diameter, sur-
rounded by a mineralized rock mass.
The bulk of the mineralization within
the orebody is typical of massive, homo-
geneous copper porphyries. In fact, El
Teniente is one of the largest porphyry
deposits of copper in the world. The main
rock types of the deposit are: andesite
73%, diorite 12%, dacite 9% and breccia
6%. At some time during its history,
the deposit was affected by supergene
alteration through percolation of mete-
orological water close to surface, which
gave rise to secondary mineralization.
This secondary ore is high in copper
grade, but weak, and of good fragmen-
tation and caveability. In contrast, the
deeper primary mineralization is rela-
tively low in copper grade, harder, and
of moderate fragmentation and cavea-
bility. As can be appreciated, secondary
ore and primary ore require very differ-
ent approaches in terms of mining.
Mining method
El Teniente produces some 334,000 t fine
copper and 4,720 t molybdenum each
year. Mass caving methods are employed
to deliver approximately 98,000 t/day
of ore to the mill from several sectors
underground, each sector being, in effect,
a large mine in its own right. This case
story focuses on the Esmeralda Sector,
which is set to become the most impor-
tant section of the mine, producing
45,000 t of the 130,000 t/day planned
for El Teniente.
Since El Teniente began operations
in the early 1900s, several exploitation
methods have been used, though the se-
condary mineralization was ideally sui-
ted to conventional block caving.
However, the last mining sector lo-
cated in secondary ore, Quebrada
Teniente, was exhausted in 2003, and
all current mining is in primary ore
for processing at the expanded Colón
concentrator.
El Teniente started large-scale mi-
ning of the primary ore in 1982, using
LHDs and the fully mechanized panel
caving method. The essential difference
between panel caving and conventional
block caving is that the former is a dy-
namic method in which the undercut is
being continuously developed, and
drawpoints incorporated at the extrac-
tion front, rather than being fully de-
veloped before caving is started. This
method has been broadly successful at
El Teniente, and close to 250 million t
of ore have been extracted using panel
Traditional block caving layout.

El Teniente, Chile
caving in primary rock. Currently, two
forms of panel caving are in use: stan-
dard panel caving as applied in the
Teniente 4 Sur Sector; and panel
caving with pre-undercut as used in the
Esmeralda Sector.
Exploitation sequence
The panel caving exploitation sequence
initially used involved development
and construction of production levels,
undercutting at the undercut level, and
ore extraction. However, the dynamic
caving fronts, under high stress condi-
tions of 40-60 Mpa, resulted in sub-
stantial damage to the infrastructure.
Indeed, extraction in El Teniente Sub
6 Sector had to be stopped in March,
1992 after several rockbursts caused
fatal accidents, reflecting the low level
of knowledge at the time about mining
in primary rock.
Between June, 1994 and August, 1997,
El Teniente carried out experimental
mining in a pilot area of 12,000 sq m.
This process was closely monitored, and
the data served as the basis for a full
geomechanical study. From September,
1997 to June, 1998, during the pre-
operational phase, it was realized that
it was necessary to research the rela-
tionship between seismic potential,
undercutting speed and the mining of
new areas. Because of this, and for the
first time since the 1992 production
freeze, El Teniente carried out prepara-
tory work in a 6,000 sq m area using
simultaneous production techniques.
The test succeeded, with no significant
rockbursts, thus proving the relation-
ship between seismicity and caving
speed. Indeed, it is now recognized that
the uncontrolled seismicity induced by
the mining extraction rate of advance
of the caving face and extraction speed
has been the main cause of damage to
the tunnels and infrastructure on the
lower levels.
Nowadays, there are variables incor-
porated into the mining design and plan-
ning concept to control the excess of
seismic activity, not only improving the
working conditions on the production
level, but also increasing productivity.
During the pre-operational phase, over
2 million t were removed from Teniente
Sub 6, with only two small rockbursts.
Esmeralda pre-undercut
Following on from the studies and con-
trolled tests, El Teniente introduced a
variation of its conventional panel ca-
ving undercut sequence. Known as
pre-undercut, it essentially consists of
developing the production level behind
the undercut, rather than the more
typical method where the production
development is carried in parallel with
the undercut ahead of the caving face.
The pre-undercut achieves a better re-
distribution of the stresses ahead of the
production development, resulting in
less damage and improved safety.
Although the pre-undercut variant
had been tested in some small sectors of
the mine, it was first used on an indus-
trial scale in the new Esmeralda sector.
Occupying a total area of 714,000 sq
m, Esmeralda is located at 2,210 m asl
within the El Teniente deposit, bounded
on the west by the Braden breccia pipe,
and in the north by El Teniente Sub 6
Sector, and is below the Teniente 4 Sur
Sector. Lithologically, it occurs mainly
in andesite, and contains a total mineral
reserve of 365 million t, with an average
grade of 1.01% of copper and 0.024%
of molybdenum. The total investment
for Esmeralda was US$205.6 million,
with conceptual engineering and design
initiated in 1992, and caving starting in
August, 1996. Ore production started in
September, 1997, and has built up from
an average of 4,000 t/day in 1998 to
19,500 t/day in 2001, and full produc-
tion of 45,000 t/day from 2005.
Caving at Esmeralda was achieved
with 16,800 sq m of available produc-
tion undercut, once a problem of 'sup-
port points' was solved. These formed
above the apex of the crown pillar, and
reduced the interaction between draw-
points, making the flow of ore from
Panel caving with pre-undercut at Esmeralda.

El Teniente, Chile
the undercut level difficult. The effec-
tive extraction rate defined for the Es-
meralda sector was 0.14 to 0.44 t/day/
sq m at the initial caving stage, and
reached 0.28 to 0.65 t/day/sq m at the
steady-state caving stage. The height
of primary ore column to be exploited
is around 150 m, relatively low if com-
pared with Teniente 4 Sur, where the
height is over 240 m.
At Esmeralda, 7 cu yd LHDs work-
ing on the production level load and tip
into 3.5 m-diameter ore passes. Here,
teleremote controlled hydraulic break-
ers positioned above 1 m x 1 m grizzlies
break any oversize rock before it goes
through the ore pass and into the loa-
ding bin. On the haulage level, the
mineral is loaded into trains featuring
Automatic Train Protection (ATP) and
consisting of a locomotive with eight 50
t cars. These trains, which were retrofit-
ted with an Automatic Train Operation
(ATO) system, tip into storage bins
which feed a 5.0 m-diameter orepass
to the main transport level Teniente 8.
Trains with 90 t electric locomotives
and 18 cars each of 80 t capacity carry
the mineral out to the Colón concentra-
tor. The main haulage level at Teniente
8 was recently upgraded, incorporating
new technology similar to Esmeralda.
Basic concepts
In the conventional panel caving and the
pre-undercut variant, the same basic con-
cepts apply. The main difference is the
sequence of each of the operational ele-
ments. In the conventional panel caving
method, the sequence of activities is:
development of tunnels on each level
for production and undercut; drawbell
opening; undercut blasting; and extrac-
tion. In the pre-undercut variant, the un-
dercut is excavated first, and the pro-
duction level is developed subsequently
within the stress-relieved zone: devel-
opment of the undercut level; undercut
blasting; development of the production
level; drawbell opening; and extraction.
The main challenge associated with
this variant involved the undercutting.
Several alternatives were tried, with
the current preference being a flat, low
height 3.6 m undercut. The undercut is
blasted some 80 m ahead of the actual
production zone, with the production
level and drawbell development follow-
ing around 22.5 m behind the undercut,
and 57.5 m ahead of the production
zone.
The undercut comprises drives, 3.6
m-wide by 3.6 m-high, developed paral-
lel to each other on 15 m centres. The
excavation of the undercut is achieved by
blasting three- or four-hole fans, some
7 m to 10 m length, drilled into the side-
wall. The drill holes are fanned slightly,
to ensure an undercut height equal to
the height of the drives. Swell material
from each undercut blast is removed by
LHD to provide a free face for the next
blast. The production haulage level is
developed 18 m below the undercut,
giving a crown pillar thickness of 14.4
m through which the drawbells are then
developed straight into the pre-blasted
undercut. The production level requires
substantial support, with fully grouted
2.3 m rebar installed in a 0.9 m x 1.0
m pattern immediately behind the face,
followed by chain mesh and shotcrete.
Permanent support is added around 15 m
behind the face, and consists of fully
grouted long cable bolts, with additional
reinforcement at drawpoints. One of the
challenges of this method is that two
mining fronts have to be managed, one
on the undercut level, and the other lo-
cated on the production level, and these
Plan of pre-undercut holes.
Drilling patterns in andesite and breccia.
HW FW FWHW
HW FW FWHW
Standard drill plan with 4 hole-fans
Drill plan with 3 x 3 hole-fans Drill plan with 4 x 4 hole-fans

El Teniente, Chile
in turn are related to the scheduling of
the development of the drawbells, and
construction of the drawpoints.
The pre-undercut variant has been a
substantial success in the Esmeralda sec-
tor, with only minimal damage occur-
ring on the production level, and its
associated orepasses and drawpoints.
There was a significant reduction of
damage to the drifts located under the
undercut level, as well as a significant
reduction of rockburst occurrence by
better draw management. The stability
and rock condition with the pre-under-
cut variant dramatically improves, so it
was possible to reduce the cost of sup-
port, and increase the availability of the
area by nearly 90%.
Some optimization of the pre-under-
cut is still continuing, in particular some
fine-tuning of undercut level pillars and
improvement of the co-ordination and
scheduling of the development activi-
ties. It is vital that the spacing of the ac-
tivities is maintained, so as to keep the
production development ahead of the
active cave, but still within the destres-
sed area.
Current productivity obtained at
Esmeralda is over 115 t/day/worker. In
comparison with other methods such as
sublevel caving, panel caving gives El
Teniente more advantages. The direct
cost of the sublevel caving method is at
least double that of panel caving, and
the current direct cost for mine at El
Teniente is US$2.5/t of ore, and indirect
costs close to US$1/t
The average cost of panel caving is
US$3.5/t, compared to more than US$5/t
for sublevel caving. Hence, El Teniente
is developing its new productive sectors
using the panel caving method with pre-
undercut, though other variants could
be used, depending on the local condi-
tions, lithology, stresses and economics
of each sector.
Production at Esmeralda
Cave undercutting at Esmeralda is pres-
ently carried out with the 'parallel long
hole' technique, which basically consists
of excavating an 855 cu m pillar of solid
rock 11.4 m-wide, 25 m-long and 3 m-
high. A triangular pattern of 14 parallel
long holes of 3 in-diameter, with 9 rows
of 2 holes and 1 hole each is used. This
pattern has better efficiency, absorbs
blast hole deviation, and avoids forma-
tion of residual pillars.
Drilling is carried out with an Atlas
Copco Simba H157 drill rig, whose out-
put is 60 m/shift of 3 in-diameter holes
and 85 m/shift of 2.5 in-diameter holes.
Standard ANFO is the column charge,
with 300 gm cylindrical pentolite as the
booster, detonated using Nonel.
Atlas Copco equipment at Esmeralda
includes one Rocket Boomer, two Boltec
rigs, two Simba rigs and one 3.5 cu yd
Scooptram loader.
In the production level, a fleet of
nine LHDs is used, including Atlas
Copco Scooptram ST6C and ST1000
loaders of capacities 6 cu yd and 7.3 cu
yd respectively.
The support methods used in Es-
meralda include 22 mm-diameter and 2.3
m-long bolts, 6 mm-diameter by 10 cm
spacing mesh, 10 cm-thick shotcrete, and
6 in-diameter cable bolts. There are two
types of cable bolts, plain and birdcage,
which are 4 m to 10 m-long, and 5 m to
7 m-long respectively.
Raise boring
In an interesting application during the
development of Esmeralda, two Atlas
Copco Robbins raise boring machines,
a 34RH and a 53RH were used. These
are multipurpose machines, and can be
employed for upwards boxhole boring
or down reaming, as well as conven-
tional raiseboring.
At Esmeralda, the Robbins 34RH unit
was used in the production level to drill
draw bell slot vertical holes approxi-
mately 15 m to 20 m-long and 0.7 m-
diameter. The machine worked three
shifts/day, giving a penetration rate of
2.1 m/h. It had a capacity of 93 m/month
and a utilization rate of 39%.
The Robbins 53RH was employed to
bore 1.5 m-diameter boxholes up to 75
m-long for use as ventilation shafts, and
inclined pilot raises for orepasses, with
an average length of 24 m. The machine
worked three shifts/day, giving a pen-
etration rate of 1.8 m/hr. It had a capa-
city of 111 m/month and a utilization
rate of 57.3%.
Atlas Copco trained the operators
from El Teniente, and was in charge of
the equipment maintenance during the
first few months.
Rocket Boomer drill rigs
Shortly after acquiring the raise boring
machines, El Teniente acquired two
Atlas Copco Rocket Boomer 282 drill
rigs for drift development at Esmeralda.
In order to increase the drilling pre-
cision, the mine installed the Atlas
Copco Feed Angle Measurement (FAM)
instrument on the Rocket Boomer units.
The machines also featured the direct
controlled drilling system, which in-
corporates the anti-jamming function
Rotation Pressure Controlled Feed Force
(RPCF).
The Rocket Boomer rigs were fitted
with COP 1838 rock drills with 20 KW
impact power and dual-damping system,
giving high speed drilling and good steel
economy.
Principle of pre-undercut at Esmeralda.
80 m
57,5 m 22,5 m
1. Development
2. Drilling blasting to start caving
3. Development
4. Open trenches (boxholes + drilling)
5. Extraction
Production
area
Undercut area
Preparation area
12
3
4
5
80 m
57,5 m 22,5 m
1. Development
2. Drilling blasting to start caving
3. Development
4. Open trenches (boxholes + drilling)
5. Extraction
Production
area
Undercut area
Preparation area
12
3
4
5

El Teniente, Chile
According to Atlas Copco Chilena,
which delivered the equipment, the
Rocket Boomer units exceeded the ma-
nagement's expectations, and showed
better results in comparison with the
other rigs owned by the mine. For in-
stance, in the development of 4 m x 4
m drifts, where each round required a
total of 48 drill holes of 45 mm and two
cut holes of 4 in-diameter, the Rocket
Boomer rigs drilled holes 4.0 m-long,
whereas the other rigs drilled holes 3.1
m-long. The Rocket Boomer rigs also
surpassed the older drill rigs in penetra-
tion rate (1.9 - 2.0 m/min vs 1.23 - 1.28
m/min), drill m/effective hour (150 vs
77.5), drill m per round (200 vs 155),
drilling time per round/min (85 vs 155)
and advance rounds/shifts (3 vs 1.0 - 1.5).
Maintenance programme
Today, in terms of maintenance, El Ten-
iente is close to being self-sufficient, and
does most of its own work. Maintenance
programmes for all the units are based
on the suppliers' information, plus ex-
perience gained in use. All this data is
held on a centralized system that moni-
tors all machines, checks when they need
maintenance, and organizes what spares
will be required. There are centralized
maintenance workshops for drill rigs,
LHDs and utility vehicles, with one
major workshop for each machine type.
In this way, the maintenance department
and its team provide a central technical
and maintenance service to all the sec-
tors within El Teniente. Smaller
workshops dispersed throughout the
complex are used for repair or main-
tenance jobs of less than four hours
duration. Major rebuilds and repairs
are handled at the central workshops
on surface, one for component rebuilds,
and the other for major machine over-
hauls.
Atlas Copco maintains a team of
technicians permanently at the mine,
working with the maintenance depart-
ment on the commissioning of new
equipment, and providing support and
operator training during the warranty
period of the units.
Recent developments
Framed within Codelco's current US$4.2
billion strategic plan, the US$1.1 billion
Plan de Desarrollo Teniente (PDT) is the
great mining, technical and management
strategic plan of El Teniente Division
for the next 25 years. Its objective is to
expand the production capacity at all
levels, including mine, concentrator,
smelter, hydrometallurgy and services,
and increase El Teniente's economic
value by over 90% from US$2 billion to
US$3.8 billion.
Amongst other things, the plan con-
templates the incorporation of world-
class technology.
Occupying an area of 190,000 sq m,
Reservas Norte/Sector Andesita is lo-
cated north of the Teniente Sub-6
sector. Its reserves are estimated to be
125 million t, with an average grade
of 1.14% copper. Its useful life will
last until 2019, and during operation it
will require a workforce of 280 people.
Construction was started in 2000 for
production commencement in 2003.
Production is planned to reach 35,000 t/
day and, like Esmeralda, Reservas Norte
is being exploited by panel caving with
the pre-undercut variant. Main equip-
ment includes 14 LHDs of 7 cu yd ca-
pacity, 16 plate feeders, eight 80t trucks,
four hydraulic breakers, and five 1,400
HP fans. On the production level, the
LHDs tip into 34 m-long orepasses.
On the haulage level, the 80t trucks,
loaded by plate feeders, empty the min-
eral into four storage bins fitted with
large hydraulic breakers and grizzlies.
One of the objectives of this project
was to automate and remotely control
the operations of truck haulage, plate
feeder loading, and rock reduction by
breakers.
With an area of 57,600 sq m, Pipa
Norte is located north of the Braden pipe
and south of the Quebrada Teniente
sector. Its reserves are estimated to be
27.1 million t, with an average copper
grade of 1.024%. Construction started
in 2001 for production commencement
in 2003, with a peak rate of 10,000 t/day
by 2005 and a useful life of 10 years.
The exploitation method is panel caving
with pre-undercut and low excavation,
with a labour force of 43 people and a
planned personal average productivity
rate of 220 t/day. 13 cu yd capacity die-
sel LHDs are part of a semi-automated
loading operation, with an operator on
surface remotely controlling three load-
ers. LHD transport and unloading is
fully automated.
Located south of the Braden pipe,
Diablo Regimiento takes up an area
of 201,200 sq m. Its reserves include
98.9 million t, with an average grade of
0.94% of copper. Construction started
in 2001 for commencement of produc-
tion in 2004, aiming at 28,000 t/day by
2011 with a planned life of 16 years.
Average productivity is estimated to be
230 t/day, with a peak labour force of
115 people. The exploitation method
Undercut drilling to start the caving process.

El Teniente, Chile
used is again panel caving with pre-
undercut. With a main equipment fleet
of 13 cu yd LHDs, Diablo Regimiento is
planned as a semi-automated operation,
similar to Pipa Norte.
Occupying an area of 160,000 sq m,
Pilar Sub 6/Esmeralda is bounded in the
south by the Esmeralda sector, and in the
north by the Andesita and Dacita areas,
which are located west of Quebrada
Teniente. Its reserves are estimated to
be 76.6 million t, with an average grade
of 1.27% copper. Construction started
in 2003 for first production in 2005,
and a peak rate of 18,000 t/day between
2009 and 2016. Productivity has been
estimated as being 150 t/day per worker,
with a labour force during operation of
120 people. The exploitation method
is panel caving with pre-undercut, and
main equipment includes LHDs, 80 t
trucks, plate feeders, breakers, crushers,
and drill rigs for secondary reduction.
New mine level
From 2014 onwards, El Teniente will in-
corporate the New Mine Level (NML)
project into its production plan. This
will become the most important under-
ground panel caving project, and will
sustain the production plans in the long
term, exploiting only primary ore from
an undercut level located at 1,880 m asl.
The new level will be divided into five
mining sectors, with 1,371 million t of
total ore reserves of 0.96% copper grade
covering an area of 1.6 sq km. Initial
production rate will be 2,000 t/day,
reaching 130,000 t/day ultimately.
The NML will deepen the exploi-
tation of the deposit 100 m below the
current main transport level, and will
incorporate blocks with an average of
300 m height. New infrastructure in-
cludes the transport level, service shafts,
primary crusher chambers, and drain-
age and ventilation levels.
References
This article is based in interviews with
management from El Teniente and the
following papers:
P Yanez and R Molina, New Mine
Level Project at El Teniente. Massmin
2004.
F Varas, Automation of Mineral Ex-
traction and Handling at El Teniente.
Massmin 2004.
M Larraín, Overview El Teniente Di-
vision, Presentation to MBA Students
Vanderbilt University USA, 2002.
M Barranza and P Crorkan: Esmeralda
Mine Exploitation Project. Massmin,
2000.
E Rojas, R Molina, A Bonani and H
Constanzo: The Pre-Undercut Caving
Method at the El Teniente Mine,
Codelco, Chile. Massmin, 2000.
M Larraín, P Maureira, Plan de Desar-
rollo 2000, Division El Teniente, UGA
MINCO, Executive Summary, 2000.
Atlas Copco Robbins 53RH raise borer.

Fax: +46 19 670 7393
www.atlascopco.com
Working with Atlas Copco means working with highly productive
rock drilling solutions. What’s more, the people you work with are
the best – with the ability to listen and to understand the diverse
needs of our customers. This approach requires experience and
knowledge, presence, flexibility and involvement in their proc-
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Through interaction, innovation and a continuous drive to improve
the way we do things – we help our customers achieve results.

Boxhole Boring at El Teniente
Introduction
Codelco, renowned for its refined copper
output, is also the second ranked world
supplier of molybdenum, as well as being
a major producer of silver and sulphuric
acid, both of which are by-products of its
core copper production.
The El Teniente mine, located high
in the Andes at an elevation of 2,100 m,
has been producing copper since 1904.
The orebody is 2.8 km-long by
1.9 km-wide, and is 1.8 km-deep, with
proven reserves of some 4,000 million t,
sufficient for a mine life of 100 years.
Approximately 2,800 miners work
seven levels on a 24 h/day, 7 day/ week
operation.
El Teniente production increased si-
gnificantly in 2005, when its new Es-
meralda section came on line, using the
pre-undercut panel caving method. Over-
all mine output has increased by 31,000
t/day, with 45,000 t/day coming from
the Esmeralda Project, making it the
most important sector in the mine. The
two new boxhole boring systems sup-
plied by Atlas Copco Robbins are a
vital part of this production system.
Boxhole boring at El Teniente
The lieutenant
marches on
State owned Codelco is Chile’s lar-
gest company and the world’s lar-
gest producer of refined copper.
The Codelco-owned El Teniente
(The Lieutenant) mine is presently
the world’s largest underground
mining operation. The mine ave-
rage production rate is currently
126,000 t/day. Boxhole boring be-
tween the production and haulage
levels using Atlas Copco Robbins
machines is a major component in
achieving such high outputs.
Recently, two raise borers mo-
dified to suit the El Teniente mine
conditions were commissioned by
Atlas Copco. They were evaluated
for three months, during which
time the crews were trained in
their operation. Both exceeded the
set target performance criteria.
Mining method at El Teniente.
Loading, LHD
Dumping
Robbins
34RH
Transportation level
Production level
Ventilation level
Robbins
53RH
Orepasses
Ventilation shaft,
1.5 m diameter
35 m long
Ventilation
shaft, 1.5 m
diameter
45 m long
(max: 75 m)
Slot hole
0.7 m diam/15 m long
Basic facts in new operation
Main caving level
Level: 2,210 m above sea level.
Drifts: 15 m. Section: 3.6 x 3.4 m.
Caving with horizontal cut: 4 m in height.
Production level
Level: 2,162 m above sea level.
Drifts: 30 m. Sections: 4.0 x 3.6 m.
Draw Bell: 17.3 m
Orebody (narrow cut)
Tapping
The 3.6 x 3.6 m operating limits at
the mine work sites demanded an
extremely low reamer design with
a quickly detachable stinger.
This reamer is bolted onto the
machine when not in use.
When piloting, the stinger is
removed from the reamer, to allow
the drill string to be fed through.
In reaming mode, the stinger is
refitted using the pipe loader,
and the locking bolts are
tightened manually.

Mine requirements
El Teniente tendered for the purchase of
two boxhole boring units to excavate
the draw bell slot holes for the panel ca-
ving operation. These units would also
be used to bore ventilation raises and
ore passes between the production and
the haulage level. The vertical draw bell
slots are generally 15 m-long and 692
mm-diameter. A total of 800 m, com-
prising 45-50 shafts, are bored annu-
ally.
Because drifts have not been deve-
loped on the production level, all venti-
lation raises and ore passes are bored
from the haulage level and upwards
using the boxhole boring technique. The
average length of the vertical and in-
clined ventilation raises is 25-50 m. The
inclined ore passes average 25 m-long,
but this varies up to 75 m-long. The total
annual requirement for 1.5 m-diameter
bored raises is 1,000 m.
Restrictions are placed on the ma-
chine design by the size of the under-
ground sections. Work sites measure
3.6 x 3.6 m, and maximum transporta-
tion dimensions are 2.5 m-wide x 2.5 m-
high x 4.8 m-long. The machines must
either be self-propelled or transported
on rail, and have to have tramming and
directional lights, as well as a fire extin-
guisher system. The mine electrical in-
stallations provide power at 575-4,000
V, 3-phases at 50 Hz, and 24-220 V, sin-
gle phase at 50 Hz. Each machine is de-
signed for three, or less, operators per
shift.
The operating environment is 2,300 m
above sea level, with teperatures from
+25 degrees C to 0 degrees C. Relative
humidity varies from 15% to 90% in
the mine, where acid water and occa-
sional blast vibrations may be experi-
enced. Both machines are operated 24
h/day, 7 days/week, with a maximum
machine utilization of 15-16 h/day.
Evaluation period
An evaluation period of three months
was established to study the performance
capabilities of each machine. Target per-
formance criteria for the smaller slot
hole machine was set at 264 m bored
during the three month period, and 330
m for the larger boxhole machine.
This performance target was based
on a 24 h/day operation, with net av-
ailable operating time of 15-16 h. The
number of operating personnel required,
set-up and moving time, the rate of pe-
netration and machine availability were
all recorded during evaluation period.
Atlas Copco boxhole boring units
Robbins 34RH and 53RH were found
to meet the requirements of the up-hole
boring tender, and were selected by the
mine. Built on the experience of the
52R, the 53RH multi-purpose machine
has been developed since the early
1980s. The 34RH has been used as a
raiseboring and downreaming machine
for a similar period, and was first intro-
duced in the boxhole configuration in
1998. To accommodate the restricted
working space in the mine, the already
low-profile 34RH and 53RH had to be
redesigned to further decrease the wor-
king height. Both machines are self-
propelled, and equipped with efficient
muck collectors, remote-controlled pipe
handling and automatic data logging.
Atlas Copco Robbins 34RH
The Robbins 34RH is a low profile,
small diameter raise drill, designed for
applications such as slot raises, backfills
and narrow-vein mining. This multi-
purpose, lightweight raise drill can be
used for downreaming and upward
boxhole boring, as well as for conven-
tional raise boring.
The machine features a variable
speed hydraulic drive with a two stage
planetary gearbox, and hollow-centre
shaft to enable pilot-hole flushing. To
change boring methods, the Robbins
34RH is easily turned upside down, to
orient the drive head into either upward
or downward boring position.
The Robbins 34RH was already a
true low-profile raise drill. However, to
accommodate the restricted site dimen-
sions, and to allow room for a muck-
handling system on top of the machine,
the maximum working height had to
be lowered further. This was achieved
through the use of shorter high-thrust
telescopic cylinders, and by utilizing
750 mm-long by 254 mm-diameter drill
rods.
This reduced the working height of
the assembly to 3.6 m, including the
muck handling system.
The new muck handling arrange-
ment, which had been fitted on two ear-
lier Robbins 34RH machines commis-
sioned in 1998 and 1999, has been
further developed for efficient muck
collection in the boxhole boring mode.
The remote controlled and hydrauli-
cally operated muck collector is fully
integrated into the derrick assembly, and
remains on the machine, even during
transportation.
Boxhole equipment.

During pilot hole drilling and rea-
ming, the rubber sealed muck collector
is applied adjacent to the rock face. The
muck slides on a chute assembly to the
rear of the machine.
The two earlier Robbins 34RH ma-
chines featured a 270 degree working
range, with muck spilling to either side
or to the rear end of the machine, whereas
the muck chute on the new El Teniente
34RH machine has a working range of
90 degrees, due to simpler and more
compact design.
The Robbins 34RH features a remote
controlled hydraulically operated slide-
opening worktable for use in both down-
reaming and boxhole boring applica-
tions. The entire drill string, including
boxhole stabilizers and reamer, can pass
through the worktable of the machine.
The standard frame Robbins 34RH
currently in use at El Teniente accom-
modates a 692 mm-diameter reamer
through the worktable, while a wide
frame model of the 34RH accommo-
dates a 1,060 mm-diameter reamer.
The Robbins 34RH worktable is
equipped with semi-mechanized wren-
ching, which features a hydraulically
powered forkshaped wrench mani-
pulated from the operator’s control
console.
The rod handler is designed to pick
up all drill string components, includ-
ing boxhole stabilizers and reamer.
Robbins 53RH
The Robbins 53RH is a low profile,
medium-diameter raise drill, suitable
for boring orepasses and ventilation
shafts. It is a versatile multi-purpose
machine, capable of boring upwards
boxhole, downreaming, or conventio-
nal raise boring, without modification
to the drive assembly.
It has a hydraulic drive to enable
variable rotation speeds and has dual
drive motors placed offline on a gather-
ing gearbox that transmits torque to the
drive heads.
The Robbins 53RH features a raise-
boring and a boxhole float box, which
allows the boring methods to be chan-
ged by simply installing drill rods in
either the upper or lower float box. In
addition, this multi-purpose unit is pro-
vided with a removable water swivel, to
facilitate pilot bit flushing in both raise
boring and boxhole boring modes.
The El Teniente machine has been
substantially upgraded from previous
versions of the Robbins 53RH, to in-
crease its productivity and working
range. The input power has been increa-
sed by 31% to 225 kW, the torque has
been increased by 44% to 156 kNm,
and the thrust by 21% to 3,350 kN.
To achieve the same low profile as
standard Robbins 53RH machines, high
thrust telescopic cylinders have been
used. This has resulted in a machine
with an overall height of just 2.9 m that
utilizes 750 mm-long drill rods with an
outer diameter of 286 mm.
For ease of operation, the unit is
equipped with semi-mechanized wren-
ching in the worktable, as well as the
headframe. This features a hydrauli-
cally powered forkshaped wrench ma-
nipulated from the operator’s control
console.
The larger Robbins 53RH does not
feature an opening worktable, as the
wings of the stabilizers and the reamer
are attached on top of the machine.
Muck is handled by a separate col-
lector system designed to suit the ma-
chine. Unlike the Robbins 34RH, this
muck collector is not integrated into
the machine design, but is attached to
the rock face by means of rock bolts.
As it is separated from the derrick
assembly, this remote controlled, hy-
draulically operated system provides a
360 degree working range for channel-
ling the muck away from the machine.
The remote controlled rod handling
system on the Robbins 53RH is used for
side and ground loading of drill pipes.
This configuration of pipeloader has
previously been used on all other
Robbins models, and is now available
on the 53RH. Due to the restricted ma-
chine dimensions, it is not possible to
add the stabilizers within the machine
frame. Instead, the pipeloader inserts
a stabilizer pipe with stabilizer wing
attachment sleeves.
Once this is pushed through the
headframe, the lightweight stabilizer
wings are attached to the sleeves be-
fore continuing on through the muck
collector, and into the hole.
A new reamer handling system has
been integrated into this machine de-
sign to eliminate the handling of the
reamer at each set up. The reamer has
been designed to bolt on top of the head-
frame during transport and erection.
The hollow centre design of the reamer
still allows prepiloting of the hole if de-
sired, in which case a special stinger
is inserted through the headframe and
into the reamer, whereas the reamer is
unbolted from the machine frame and
attached to the stinger. The diesel trans-
porter used for this machine is sized to
Robbins 53RH set up underground.

accommodate the derrick, including the
attached reamer.
Additional equipment
The boxhole boring machines working
in El Teniente were each delivered with
a diesel powered crawler, for rapid
movement of the derrick from site to
site. The newly designed crawler fea-
tures a cordless remote controlled ope-
rating system and a high-power Deutz
diesel engine for high-altitude operation
and minimal environmental impact.
To give the mine better control over
machine productivity, a Data Acqui-
sition System was delivered with each
machine. This records operating vari-
ables in real time, and stores them on
a memory card. It also features a dis-
play panel that shows the parameters
being recorded. The machine operator
can view any variable, as well as current
time and date, and battery life during
operation.
The recording brick is configured to
log data to the memory card every 30
seconds. During the interval, variables
are continuously monitored and key
points are logged. The Data Acquisition
System is provided with a data analysis
software package which processes the
output from the recording brick stored
on the memory card, and creates gra-
phical plots of the data. The software
also generates data files that can be
inserted into spreadsheets.
Raise drill performance
As the use of boxhole boring units was
new to El Teniente mine, the evaluation
period was preceded by startup and
commissioning of the machines. After
approximately four weeks of training
and commissioning, the machines went
into full 3-shift production, and the three
months evaluation began.
Robbins 34RH evaluation
The startup period for this machine type
included classroom and maintenance
training, and the drilling of three rai-
ses. The average net penetration rate
achieved was 0.8 m/h, or 3.9 m/day. The
startup period was strongly affected by
lack of water to flush the pilot bit, poor
ventilation, and availability of concrete
pads in the working area. However, lear-
ning progressed steadily, and the ope-
rating crew was ready to begin the eva-
luation period at the completion of one
month’s training.
During the three-month evaluation
period, seven raises of approximately
14 m in length were drilled each month.
The average production rate was 93.3 m/
month, with a total production of 280.1
m for the entire period. This exceeded
the monthly target rate of 88 m and
264 m for the full period. The average
rate of penetration during the three
months was: 1.80 m/h; 2.15 m/h; and
2.17 m/h. Machine utilization during
the evaluation period was 29.8%, with a
mechanical availability of 95.5%.
Lack of access to the machine due
to shift changes, blasting and non-worked
weekends had the greatest negative
affect on machine utilization. The se-
cond largest contributing factor was
lack of site availability. During the com-
pletion of 20 production holes, the ave-
rage move and set-up time was between
10 and 12 h. Drilling each hole took two
days, which compensated for the low
machine utilization, and provided a high
rate of production.
Some downtime resulted from the
replacement of instruments broken by
rock falling from the face, and time
was also taken to improve the protec-
tion of these parts. The boring cycle in-
cluded pre-piloting of 1 to 2 m, depen-
ding on the ground conditions. After
that, the hole was bored to full diameter
in a single pass. The 692 mm reamer
mounts two RCC raise boring cutters,
and an attachment for the bit sub and
pilot bit. During single pass boring, the
279 mm pilot bit is also engaged in cut-
ting the rock. To ensure adequate flush-
ing of the cuttings past the bit-sub, water
was pumped through the centre of the
drill string to the tricone bit.
As the drilling took place on the
production level of the block caving
operation, the hole actually broke
through into the broken ore. As there
is no access to the head, it was critical
to observe any changes to thrust and
torque on the machine, to know when
breakthrough occurred. The moment
breakthrough was achieved, boring was
stopped, as any further advance could
result in the reamer getting stuck.
Robbins 53RH evaluation
In addition to classes and maintenance
training on the Robbins 53RH, a couple
of holes were drilled as part of the com-
missioning. Again, the startup period
was strongly affected by lack of water,
poor ventilation, and availability of
concrete pads in the working area. How-
ever, as the personnel were, by this time,
well-trained raise boring operators, the
evaluation period could begin within a
few weeks.
During the three month evaluation
period, three raises of approximately
Diesel powered crawlers are used for transporting Robbins 34RH and Robbins 53RH.

40 m in length were drilled each month.
The average production rate was 111.1 m/
month, and total production was 333.2 m
for the entire period. This exceeded the
monthly target rate of 110 m and 330
m for the full period. The average rate
of penetration during the three months
was: 1.12 m/h; 2.60 m/h; and 1.63 m/h.
Machine utilization during the evalua-
tion period was 40.3%, with a mechani-
cal availability of 91.3%.
Machine utilization was again nega-
tively affected by non-worked week-
ends, blasting near the drill site, and
shift changes. The next largest factor
contributing negatively to machine uti-
lizations was site availability due to site
cleaning, waiting for concrete pads, and
the availability of electricity and water.
During the completion of nine produc-
tion holes, the average move and set up
time for the machine was between 13
and 15 h. As drilling of a hole could be
completed in a little more than 6 days,
a high production rate was achieved,
despite the low rig utilization.
The boring cycle included pre-piloting
of 2 to 3 m, to ensure the straightest
hole possible. This also facilitated easier
reamer collaring, by reducing devia-
tion caused by the dead weight of the
reamer head.
Following completion of the pilot,
the hole was bored to full diameter in
a single pass. The 1.5 m reamer mounts
eight RCC raiseboring cutters, and an
attachment for the bit sub and 311 mm
pilot bit. As with the smaller machine,
water was pumped through the centre
of the drill string to the tricone bit, to
ensure adequate flushing of the cut-
tings past the bit-sub.
Conclusion
The application environment in the
El Teniente mine placed high demands
on the boxhole boring equipment sup-
plier, both in size constraints, and in
operation of the equipment. The mine
personnel also had aggressive perfor-
mance expectations, in keeping with
the established high productivity of the
mine.
Atlas Copco chose to offer its proven
34RH and 53RH boxhole machines with
customized features to meet the special
needs of El Teniente. Most of these
features were focused on accommoda-
ting the restrictive work environment
and high performance expectations.
After thoroughly monitoring the ca-
pabilities of both machines, the project
in El Teniente has provided important
Robbins 34RH.

input to future development of boxhole
boring technology. With production re-
sults exceeding expectations, it has also
proved to be a new milestone in the ap-
plication of boxhole boring machines.
Acknowledgement
ment and staff at El Teniente for their
help and assistance with this article.
Rock properties at El Teniente.
RockType Composition Density UCS Young’s Poisson’s
[%] [ton/m3] [MPa] Modulus Ratio
[MPa] [---]
Andesite Fw 36 2.75 100 55 0.12
Andesite Hw 24 2.75 125 55 0.17
Anhydrite Breccha 20 2.70 115 55 0.17
Andesite Breccha 12 2.70 100 50 0.12
Diorite 8 2.75 140 60 0.15
Robbins 53RH-EX under test.

Antofagasta, Chile
Large operation
The Sierra Miranda Mine, located about
60 km northeast of the city of Antofa-
gasta, is one of Chile’s largest under-
ground mining operations and has a his-
tory of using the most modern mining
techniques and equipment available.
Sierra Miranda lacks a substantial
power facility, with the exception of
electricity for lighting and ventilation,
and has no water or air supply lines.
As a result, to mechanize effectively,
all of its underground equipment has
to be self-sufficient. The drill rigs, for
example, are all diesel-hydraulic with
independent water-mist flushing sys-
tems.
The mine’s total production is 3.3
million t/y, 1.1 million t of which is
waste rock from development work, and
the remaining 2.2 million t is copper
ore with an average grade of 0.75%.
The host rock is volcanic andesite
and the mineral deposit is principally
copper malachite, a combination of
copper pitch ore and chryssocholla, with
sporadic atacamite.
Three years ago, the mine owner star-
ted the first stage of modernizing the
mine’s operations. This required the
latest generation of equipment in order
to improve the systems for extraction
and the mining processes.
Atlas Copco fleet
Sierra Miranda is one of the few, and
possibly the only mine of its size in the
world, that is equipped with diesel-
hydraulic machines.
Currently, the mine production drill-
ing fleet is all Atlas Copco, including
a Simba M6 C, four Rocket Boomer
L1 C drill rigs equipped with the RCS
computerized rig control system, and a
Scaletec scaling rig, which is the first of
its kind in Latin America.
In addition, the mine has five Atlas
Copco ROC 460 PC drill rigs, and
Diamec U6 and CT14 exploration rigs,
as well as various mobile compressors.
The production fleet of mobile eq-
uipment comprises four Scooptram
ST1020 remote controlled loaders. A
Scooptram ST2G loader and an addi-
tional Simba are also expected to join
the fleet this year.
The owner is investing in the latest
generation of equipment in order to
grow the mine as quicly as possible, and
the selection of Atlas Copco machines
has provided the exact match for this
requirement.
Efficient production
Sierra Miranda has a workforce of about
300, including contractors’ personnel.
The mining method is sub-level stop-
ing, without backfill. As the orebody is
relatively narrow at 4-10 m-wide it is
necessary to use an extraction method
that is both precise and focused.
The deposit is situated near the
surface, which from a geo-mechanical
point of view is favourable, as the sup-
port pillars in the mine are not subjected
to excessive pressure.
Until recently, Atlas Copco ROC 460
truck-mounted drill rigs with short
feeds and DTH hammers were used
Modernization at Sierra Miranda
Computerized
systems
The Sierra Miranda copper mine
in Chile has undergone a complete
transformation over the last year,
as a result of which it is now rated
as one of the most modern mines
in Latin America. Along the way,
the mine has acquired a purpose-
matched fleet of new generation
Atlas Copco equipment, capable of
high output without the availabil-
ity of a high tension underground
electricity supply. To support this
process of modernization, pro-
active and preventive service and
maintenance is essential, and the
management at Sierra Miranda
know that good aftermarket sup-
port for this type of advanced eq-
uipment is vital in order to achieve
their production goals. It was for
this reason that the mine entrusted
Atlas Copco as a true partner, ha-
ving confidence in their reputation
as a serious company with a lot of
experience.
At the controls of a Rocket Boomer L1 C drill rig. Operators at the Sierra
Miranda mine appreciate the benefits of the computerized systems.

Antofagasta, Chile
for drilling the blast holes, and also for
developing 40 m-deep raises between
the levels.
In order to minimize dilution in the
narrowest veins, it was decided to em-
ploy a Simba M6 C drill rig equipped
with a COP 2550 rock drill on pro-
duction drilling of downholes in this
narrow vein/sub-level stoping opera-
tion. At the same time, the distance
between levels was reduced to 25 m and
the hole diameter was reduced from 4
in to 3.5 in.
The Rocket Boomer L1 C rigs are used
both for development and production.
Each rig, equipped with a single COP
1838HF rock drill, advances at a rate
of 800 m/month in galleries that are 5
m-wide x 5 m-high. Scooptram ST1020
loaders are used for hauling and trans-
port during the development of galleries
and ramps.
The Scaletec is used throughout the
mine for preparing faces for loading and
for general roof scaling, mechanizing an
operation that was previously time-con-
suming and sometimes dangerous.
The ore is transported to the surface
by conventional 40 t-capacity trucks.
Change for good
The technological changes at Sierra
Miranda have been rapid. In less than
a year, the entire mine fleet has been
upgraded to modern equipment. In ad-
dition, the operators have acquired new
skills and the whole team is now focused
on increasing the planned production
levels and on improving risk and secu-
rity standards.
Furthermore, productivity has in-
creased beyond all expectations. While
the improvements continue, the mine is
also making every effort to achieve ISO
9000 certification.
At Sierra Miranda Atlas Copco works
in a very proactive way. The fleet is
checked daily for the number of hours
each machine has worked, and the
causes of any breakdowns. It is then
decided which machines will be re-
quired for work over the following few
days, and Atlas Copco makes sure that
they are available. This entails a very
flexible programme of maintenance
and follow-up procedures, which can
change from one day to the next.
At the start of the contract, the mine
stipulated that it required 90% equip-
ment availability. This took a little time
to achieve while training was underway.
However, once all systems were up and
running, availability increased to its
present level of more than 95%.
Acknowledgements
Atlas Copco is grateful to the owner
and management at Sierra Miranda
mine for their assistance with the pre-
paration of this article which first
appeared in Mining Construction
1-2007.
Schematic of sublevel stoping in a narrow vein using the Simba M6 C to drill down holes.
Scaletec in action at Sierra Miranda. Close-up of the Scaletec at work.

Mount Isa, Australia
Geology
The mineral deposits zone at the central
Mount Isa mining complex lie in an ap-
proximate North-South orientation, and
dip towards the West.
Economic copper sulphide miner-
alization lies within a brecciated sili-
ceous and dolomitic rock mass, known
locally as ‘silica-dolomite’, which is
broadly concordant with the surround-
ing Urquhart Shale. There are several
copper orebodies. The silica-dolomite
mass which hosts the 1100 and 1900
orebodies has a strike length in excess
of 2.5 km, a maximum width of 530 m,
and a height of more than 400 m. The
recently developed 3000 and 3500 ore-
bodies lie as deep as 1,800 m. Copper
mineralization is truncated by a base-
ment fault, bringing altered basic volcan-
ic rocks (Greenstone) into contact with
the Mount Isa Group sediments. The
dominant sulphide minerals are chal-
copyrite, pyrite and pyrrhotite forming
complex veins and irregular segregations
within the breccia mass.
Mount Isa’s stratiform silver-lead-
zinc sulphide mineralization occurs with
pyrite and pyrrhotite in distinct bands
dipping to the west, concordant with
weakly bedded carbonaceous dolomitic
sediments of the Urquhart Shale. The
mineralization is intermittent through a
stratigraphic interval of over 1 km, but
the major orebodies are restricted to the
upper 650 m. The orebodies occur in
an echelon pattern, interlocking at the
southern and lower sections with the
extremities of the silica-dolomite mass
hosting the copper orebodies.
The position, extent and metal con-
tent of copper and silver-lead-zinc
Mount Isa at sunset.
Boltec 335S at Mount Isa.
Mount Isa mines continues to
expand
Quadruple ores in
Queensland
Mount Isa Mines, located in north-
west Queensland, having an an-
nual ore production in excess of
10 million t, constitutes one of the
larger underground mines in the
world. It is wholly owned by MIM
Holdings, and is one of few places
in the world where four minerals
are found in substantial quantities,
and mined in close proximity. The
mine is one of the three largest
producers of lead in the world, is
the fifth largest producer of silver,
the 10th largest producer of zinc,
and is the 19th largest producer of
copper. Another superlative is that
the recently developed Enterprise
copper mine is the deepest mine
in Australia. Atlas Copco equip-
ment is widely used at the Mount
Isa Mines for production drilling,
raise boring and roof bolting.

orebodies have been established by ex-
ploration drilling from the surface and
underground. Despite the depth of the
mines, stresses in the ground are not
as great as at some shallower mines in
other regions of Australia.
History and development
John Campbell Miles discovered silver-
lead ore at Mount Isa in 1923. Although
mining began in 1924, Mount Isa Mines
didn’t make a profit until 1937, due to
problems of isolation, mine flooding and
shortage of capital.
Lead-zinc-silver production was the
original focus of Mount Isa Mines.
Although short periods of copper pro-
duction had occurred during World War
II, parallel production of copper did not
begin until 1953, after extensions to the
mining operations. The development of
copper orebodies in the late 1960s and
early 1970s, as well as improvements
to the Company’s Townsville refinery,
greatly increased copper production.
The Mount Isa group comprises se-
veral mines. The Hilton lead-zinc-
silver mine, 20 km north of Mount Isa,
opened in 1989, and is now incorpo-
rated into the George Fisher Mine. The
next large development came in the late
1990s, when close to $1bn was invested
in projects, including the new George
Fischer lead-zinc-silver and Enterprise
copper mines, as well as expansion of
the copper smelter and the Townsville
refinery.
The Enterprise is an extension of the
Mount Isa mine, in the deep 3000 and
3500 orebodies lying beneath existing
mining zones.
Simba H4353 long hole drill rig with COP 4050 rock drill.
Longitudinal section of Mount Isa mine.
4/L
5/L
6/L
7/L
10/L
12/L
14/L
16/L
13C
18/L
Rio Grande
Open Cut
BlackRock
9/L
11/L
13/L
15/L
17/L
19/L
Black StarOpenCut
20/L
21/L
Orebodies
LONGITUDINAL SECTION
COPPER MINE
Shaft
R60Shaft
M37Shaft
I54Shaft
Y59Shaft
L44Shaft
U51Shaft
X41Shaft
W44Shaft
StoragePit
S50FillPass
U47Shaft
M48Shaft
U62Shaft
P63Shaft
M61Shaft
R62Shaft
StoragePit
N52FillPass
R67Shaft
M64Shaft
H75Shaft
P61
H70Shaft
M73Shaft
Black Star
Racecource
Orebodies
3000

3500
Orebodies
1900 Orebody
400 Orebody
Black Rock

Black Star
Orebodies
1100 Orebody
LEAD
MINE
ISA
ENTERPRISE MINE
Copper Orebodies
Zinc, Lead, Silver Orebodies
2kms
4 kms
ZN

The new orebodies, 1,500-1,800 m
below the surface, are accessed by de-
clines from the bottom of the main U62/
R62 Mount Isa shaft complex. Central
to Enterprise is the new ore handling
system, including a 2 km underground
conveyor (V63 and M62) and a 713
m-deep, 5.3 m-diameter internal shaft
(the M62), which is boosting capacity
to extract the high-grade ore. A 2.13 m
x 1.98 m jaw crusher reduces the ore
down to less than 400 mm pieces at a
rate of up to 1,000 t/h. The 378 m-long
V63 conveyor carries the crushed ore to
the M62 shaft, where it is hoisted to the
20 level. The hoist is controlled from
a surface control room, and operates
at up to 16.8 m/s. From there the ore
is loaded onto the M62 conveyor for
delivery to the existing U62 copper
ore handling shaft via a short orepass.
Commercial production began from
Enterprise in July, 2000 following five
years of development work. The ore has
a high grade of 4% copper, justifying
development at such depths. The devel-
opment is predicted to provide ore for
the smelter after 2020, as production
from the 1100 orebody declines. Annual
production increased to 3.5 million t of
ore by 2004.The other main copper
resources at Mount Isa are the 1900 and
1100 orebodies, the latter known also as
the X41 mine named after the shaft that
reaches the 21 level.
MIM Holdings’ lead-zinc-silver comes
from the company’s lead mine at
Mount Isa (Racecourse orebody, etc)
and its George Fischer mine. At these
mines the lead-zinc-silver ore is mined,
crushed and hauled to the surface. Ore
from the George Fischer mine is taken
via an off-highway haulage road to the
Mount Isa facility for processing.
The total extent of the Mount Isa
mine workings is now 5 km in length
and 1.2 km in width, with the deepest
point (Enterprise mine) approximately
1,800 m underground.
Mining methods
The zinc-lead-silver orebodies and
copper orebodies are mined separately,
using slightly different methods, al-
though all operations use forms of open
stoping. In open stoping, blocks of ore
that make up part of the orebody are re-
moved one at a time, with the ultimate
goal of removing all of them.
In the Mount Isa copper mine ore-
bodies, sub-level open stoping, coupled
with secondary and tertiary stoping is
used to extract the ore. Blocks of ore
40 m-wide, 40 m-long at full orebody
height are removed. To do this, 5.0 m
x 5.0 m drilling sublevels are devel-
oped at 40 m intervals. At the bottom of
the stope, a number of drawpoints are
mined and equipped to extract the ore.
Blast hole drilling is carried out using
a variety of Atlas Copco Simba rigs, in-
cluding models H4353, H1354, 366, 269
and 254. On the extraction level, upholes
in a ‘V’ shape are used to shape the
trough. On the drilling sublevel, the
Simba rigs are used to drill holes in a
radiating fan shape. A slice of ore the
height of the stope is extracted first,
exposing an open area along one side of
the stope, into which progressive bla-
sting is carried out.
The fleet of Simba rigs covers a wide
range of hole lengths, diameters and
orientation possibilities for flexible ore-
body exploitation capabilities. Holes can
be drilled accurately, with stringent to-
lerances, for optimum fragmentation of
the ore, and minimal underbreak. Top-
hammer or ITH (in-the-hole) hammer
Stoping sequence at Mount Isa mine.
Primary Stope
Secondary Stope
Tertiary Stope
Pre-existing primary stopesEgg crater pattern
4500N
5000N
5500N
1500E
2000E
3
3
2
1
3 3 3
2 2 2 2 2
3 3
3 33 3 3 3
3 3
3 3
3 3
3
3
3 3
3 3
3 33
2 2 2
2
2
2
2
2 2 2
2 2 2 2 2
2 2 2 2 2
3 3 3 3 33
1 1 1 1
1
1 1
1 1 1
1 1 1
1 1
1 1 1 2
Advance south
S48 Fault

drilling is possible for hole lengths of
over 50 m. Flexibility of use is pro-
moted by the modular construction of
the rigs so that, for example, the feed
positioning system can be combined in
different ways to obtain the required
hole positions and directions. Types
of drilling that can be handled include
bench drilling, fan drilling within a 90-
degree sector, 360-degree ring drilling,
and parallel hole drilling.
The Simba H4353, for example, is
an all-hydraulic unit for large-scale ope-
rations, carrying out 90-degree fan
drilling, 360-degree ring drilling, or
parallel hole drilling at 1.5 m intervals.
The feed beam can be inclined 20
degrees forward and 80 degrees back-
wards. The hole diameter range is 89-
127 mm, to a maximum recommended
hole depth of 51 m. Drilling control is
automatic, using the Atlas Copco COP
4050 rock drill.
ANFO is the main explosive, mixed
on site. It is not uncommon for it to be
used to blast 100,000 t in a single firing.
The broken ore falls to the bottom of the
stope, and is extracted at the drawpoints
by diesel-powered LHD wheel loaders
with a 6.1 cu m bucket capacity. Then
the ore is either tipped directly into
the passes to feed the crusher or, if the
stope is a long way from the crusher,
into articulated haulage trucks. After
crushing, the ore is sent via a 1.6 km
cable belt to the U62 hoisting system,
where 36 t skips take it to the surface.
Mount Isa aims at 100% extraction
so, in this method, pillars between
blocks also need to be recovered. To
achieve this, open ore stopes are filled
with a cement-based slurry and/or rock
mixture. The slurry is a mixture of Port-
land cement and concentrator tailings,
whilst the rock is sourced from sur-
face stockpiles, from the heavy media
rejects from the lead concentrator, or
slag waste from the copper smelter.
The mixture sets into a hard, rock-like
formation, providing a stable face to
enable extraction of the adjacent ore
pillar.
Over half of the site’s production dril-
ling units are Atlas Copco Simba rigs.
As well as these, Atlas Copco Boomer
rigs are used for rockbolting. At Mount
Isa, in total, there are 27 drill rigs for de-
velopment and rockbolting, 17 pro-
duction drill rigs, 33 LHD loaders, 16
articulated dump trucks for longer haul-
age, and seven raise drills.
Zinc-lead-silver extraction
Panel stoping and bench stoping are
used in the zinc-lead-silver mine,
although sublevel open stoping has
been introduced as well, where suit-
able. Whereas bench stoping involves
mining the orebody longitudinally, panel
stoping involves mining the orebody
transversely. Panel stoping is still an
open stoping method, and was consid-
ered more efficient for mining the wider
orebodies at George Fischer. Bench
stoping is still the preferred method for
the mine’s narrow orebodies.
Prior to the current benching method
being introduced in 1992-93, cut-and-
fill was used. In the cut-and-fill method,
a horizontal slice of ore up to 4 m-high
is extracted from the length of the ore-
body. Although very selective in high-
grade ores, the method is also expen-
sive.
Benching was introduced as a safer
and more efficient method. The cut-
and-fill method requires a lot of ground
support, as miners work in the orebody
itself. With open stoping, workers are
positioned outside the orebody, in a much
safer working environment. Despite the
larger open void, benching is more cost
effective as less support is required,
and the ore can be extracted more effi-
ciently.
In benching, horizontal tunnels, or
‘sill drives’, are driven the length of the
orebody at regular vertical intervals.
The distance between sill drives depends
on local ground conditions, and is ty-
pically 15 m. Blast holes are drilled
vertically down from one sill drive to
the lower sill drive. Starting at one end
of the bench, a row of holes is blasted
to remove the rock between the two
sill drives. The broken ore drops to the
bottom of the orebody, and is removed
by LHD to the orepass. It is necessary
for the loader to go inside the stope to
remove the ore, so fill is progressively
introduced to the cavity to add stability
General view of sublevel stoping at Mount Isa copper mine.
Broken ore
Cutoff raise
Cutoff slot
Drilling sublevel
Drawpoint
Drilling pattern

to the hanging wall. The fill used on
site includes uncrushed underground
development rock spoil, heavy media
reject from the process plant, or hydrau-
lic sand fill from the surface.
The potential hazards of loading out
from within an open stope have been
tackled by technical development. With
the benching method, teleremote pro-
duction loading was also brought in.
With this system, employing CCTV
cameras on the front and back of the
LHD, operators can now handle up to
three units by remote control from one
location. This is an air-conditioned
cabin, which may be up to 1 km away.
The system saves time spent on a job,
increases operator safety, and gives ope-
rators more control.
The technology was practically ahead
of its time when introduced, because
it is still current. It was a step towards
the development of today’s equipment
with built-in navigational systems.
Benching has increased productivity,
improved safety, reduced costs and
provides better utilization of equipment.
The extensive mine workings at Mount
Isa incorporate a total length of under-
ground openings including road-ways,
orepasses and shafts, of approximately
975 km. The workings produce 10 mil-
lion t/year. Most mines have at least one
particular form of technical challenge,
and at Mount Isa it is heat, due to the
great working depths. The virgin rock
temperatures are around 60 degrees C.
However, with proper ventilation the
mine’s wet-bulb temperature is below
23 degrees C. The Mount Isa ventilation
system is one of the largest of its kind
in the world, and includes bulk coolers
on the surface to cool the air before it
goes underground.
Tailor made stope design at Mount Isa copper mine.
19/L
19/L
19C
19A
19C
18B
18E
18E
17D
16B
16B
Current practice in stope design
Match stope outline with grade contour.
Consider existing development horizontal
vertical (inaccessible).
Design additional development as required
for stope extraction.
Use rock mechanics principles (pillars,
exposure dimensions).
Location quality of faults fill masses
(delay exposure).
Extraction options
Simplify stope extraction sequence.
Minimize remote mucking.
Delay exposing faults and fill masses.
Effective ventilation circuits.
Safety considerations hazard ID.
Design - Monitor operating
Huge savings in drilling consumables
An alliance between MIM and Atlas
Copco Secoroc has resulted in a reduc-
tion of annual bit consumption from
28,000 to just 11,000, with no changes
in tonnages. For more than 15 years,
Secoroc had held a supply-only con-
tract for drilling consumables with
MIM. When taking over the role of
General Manager, they reviewed the
contract and found a throw-away cul-
ture that, if turned around, had the
potential to markedly save costs and
improve safety. The original consuma-
bles contract was not providing enough
information to the supplier. This reali-
zation was instrumental in changing
the contract from supply only, to full
service and supply. MIM is a very large
and busy company, making the focus
on drilling consumables difficult.
MIM undertook the task of gener-
ating information and sharing it with
Secoroc, to release the mutual ben-
efits of reduced costs for the client and
contract extensions for the supplier.
To foster continuous improvement,
quarterly meetings were implemented
to discuss the provision of service
– prompt reporting of loss, product
training and product development.
Both parties agree on what has and
what hasn’t been done, focusing on
the objectives. As a result, Secoroc is
able to provide the most suitable and
cost-efficient products for MIM opera-
tions, resulting in fewer bits for the
same tonnages. MIM and Secoroc are
now really pushing the idea of reusing
material and focusing on wastage. Bit
resharpening, rod straightening and
rod clearing have been introduced with
the resharpening ratio for development
bits now averaging 1.5 times.
Consumable care is an area where
the jumbo operators can improve the
life of consumables and cost per metre,
and Secoroc is required to take a lead
in education in the use of its products.
The companies are working towards
agreeing on and setting expectations
about scaling standards, and proce-
dures to reduce damage.
The initial supply and service con-
tract ran for one year and has since
been extended for three years on a per-
formance-based rolling contract, with
three monthly performance reviews.
Atlas Copco Secoroc workshop at Mount Isa Mines.

Ore processing
Lead-zinc-silver ore from Mount Isa
and George Fischer mines is ground to
a fine powder at the Mount Isa facility,
after which a flotation process is used
to separate waste, and produce lead-rich
and zinc-rich concentrates.
Lead concentrate from Mount Isa
contains 50-60% lead, and around 1
kg of silver/t. After smelting to remove
further impurities, blocks of material,
each containing approximately 3,984 kg
of lead and 10 kg of silver, are trans-
ported by rail to Townsville for ship-
ment to MIM’s lead/silver refinery
in England. In 2001-2002, lead-zinc
concentrator throughput and recovery
increased, and there was improved plant
reliability at the lead smelter.
Around 51% zinc concentrate is also
railed to Townsville for refining, or ship-
ment to overseas customers. MIM cur-
rently produces approximately 190,000
t of lead bullion and 500,000 t of zinc
concentrate each year.
At the Mount Isa processing facility,
there is a chimneystack at the copper
smelter, built in 1955, which is 155 m-
high, and at the lead smelter the stack,
built in 1978, is 270 m-high. Copper is
produced electrolytically in the form
of anodes. Each weighs 375 kg and is
99.7% pure copper.
Expansion plans
In the year ending June, 2002, record
copper smelter production of 233,000 t
of anode was achieved. This was up
from 207,000 t for the previous year.
A recent copper study to improve
reserves and efficiencies has resulted in
an increase in reserves to 12 years. This
has led to a planned 40% expansion in
copper production by 2006. A rate of
400,000 t/y for up to 20 years from
Mount Isa and MIM’s Ernest Henry
Mine is predicted by MIM.
MIM is planning to expand copper
production by developing the 1900 ore-
body, the Enterprise Mine 3000 and
3500 orebodies, and the surface open
pit mines in and around existing orebod-
ies. The aim for 2003 was to increase
Mount Isa copper production to 245,000
t, improve the recovery rate in the con-
centrator following an upgrade, and
increase plant utilization by improving
maintenance practices. It is estimated
that Mount Isa has over 6 million t of
contained copper still to be mined, more
than has been extracted over the past
60 years.
In more detail, the 2002 reserves and
resource report gave a total of proved
and probable ore reserves of approxi-
mately 73 million t at 3.3% copper
(previously 47 million t at 3.6% copper).
The total underground measured, indi-
cated and inferred resources, including
reserves, were approximately 116 million
t at 3.3% copper (previously 88 million t
at 3.7% copper). In addition there were
a total open-cut indicated, inferred re-
sources of 255 million t at 1.2% copper
(previously an inferred resource of 112
million t at 1.6% copper).
The improved lead-zinc concentrator
performance and smelter reliability in
2001-2002 contributed to an increase in
production from 140,000 t to 161,000 t
and reduced operating costs. Still, MIM
is planning to reduce off-site realization
costs such as transport and smelting,
which represent up to 60% of total pro-
duction costs at present.
Acknowledgements
agement of Mount Isa Mines, and in
particular to Jim Simpson, General
Manager Mining, Lead Zinc, for writing
this article which first appeared in
Underground Mining Methods, First
Edition.
Mount Isa mines – the company
Wholly owned by MIM Holdings,
Mount Isa Mines (MIM) has 2,000
permanent employees at its Mount Isa
and Townsville operations, and over
5,800 employees in other operations
across Australia and overseas. In addi-
tion to the Mount Isa complex, MIM
has copper mines at Ernest Henry in
Queensland, and a 50% interest in
the Bajo de la Alumbrera project in
Argentina. For lead-zinc-silver,
there is the George Fischer mine (in-
corporating the former Hilton mine)
in Queensland, which uses the Mount
Isa and Townsville processing facili-
ties, and a majority interest in the
McArthur River mine in Australia’s
Northern Territories. There is a gold
mine at Ravenswood, and extensive
coal operations. The latter comprise
coking coal at Oaky Creek, steam coal
at Newlands, and steaming and coking
coal at Collinsville. There is also coal
shipping from Abbot Point and Dal-
rymple Bay, and a coking plant at
Bowen Basin. All are in Australia.
MIM’s sources of revenue from all
mines are split by products: copper
31%; by-product gold 8%; Ravenswood
mine gold 1%; zinc 18%; lead 8%;
silver 4%; coal 30%.
Markets for Mount Isa’s copper are
Australia (33%), Asia (53%); and
Europe (14%). Mining finance group
Xstrata owns MIM Holdings.
Scooptram loader at Mount Isa.
Table: Mount Isa mine life production statistics
Resource Tonnage (million t)
Total lead-zinc ore mined and processed 100
Total copper ore mined and processed 200
Total copper resource remaining 400
Total lead-zinc resource remaining 200

melbourne, australia
Long history
Stawell Gold Mine, located about 250
km west of Melbourne, was first mined
in 1853. It was closed in 1926, and stayed
dormant for more than 50 years. It then
re-opened in 1982, and has been in
operation ever since.
From 1992 until 2005, Stawell was
owned by MPI Mines, who instituted a
plan to increase gold production from
100,000 oz/yr to 130,000 oz/yr by
end-2006. However, the mine recently
changed hands, and is now operated by
Leviathan Resources, who have adopted
the same objective. To meet these tar-
gets, bench stoping with cemented rock
fill pillars in primary stopes is used.
With this mining method, approxi-
mately 80% of the ore is recovered from
the stopes. Remote-controlled loaders
shift the ore out of the stopes, from where
a fleet of four Atlas Copco Minetruck
MT5010 trucks is employed hauling
it to the surface along a gravel roadbed
maintained by two graders in continu-
ous operation. Stawell management is
convinced that the MT5010 is the best
truck on the market in terms of load
capacity and performance.
Faster is better
Stawell is a very deep mine with in-
cline access. Inevitably, the adit is the
bottleneck in the production operation,
because it limits the size of truck that
can be employed hauling ore to surface.
However, within the normal under-
ground speed constraints, the faster the
trucks, and the cleaner they run, the
greater will be the amount of ore that
gets to surface.
At Stawell, getting the ore to surface
involves an 8-9 km drive, which, even
with the MT5010, involves a round trip
of 100 minutes. On the 1:8 gradient, its
speed under full 50 t load is 12 km/h,
some 2-3 km/h faster than the next fast-
est truck on the current market.
This is because the MT5010 has the
greatest power-to-weight ratio of any
truck in its class, giving it the highest
possible travel speeds per tonne.
Based on the success of the site’s
first MT5010, commissioned in 2003,
the mine subsequently ordered another
three, with the latest arriving on site in
early January, 2005. Together, the new
fleet has helped Stawell to its medium
term objectives while reducing the mi-
ning cost/tonne to the lowest it has ever
been.
Comfortable power
The Atlas Copco Minetruck MT5010 is
currently offered with the Cummins
QSK-19-C650 engine as standard. This
High speed haulage at Stawell
Keeping on
track
Trucking ore from a depth of one
kilometre beneath the surface can
be a slow and expensive process,
but it’s a thing of the past for the
Stawell Gold Mine in Australia,
where high speed haulage using
a fleet of the latest Atlas Copco
Mintruck MT5010 trucks plays a
major role in the operation. Getting
the ore out involves a long drive
up the sublevel ramps at 1:8 to the
400 m level, and then on an in-
cline of 1:10 to surface, a journey
of 8-9 km. The drivers report that
the MT5010 is the smoothest ride
in all their experience, and the
management is obtaining their
lowest-ever cost/t. The MT5010 is
providing a very good return on
investment!
Visual inspection of a Minetruck MT5010 with full load near Stawell portal.

water-cooled diesel provides an MSHA
power rating of 485 kW (650 hp) at 2,100
rpm, has a displacement of 19 litres
(1,159 cu in) and a six-cylinder, in-line
configuration. It is designed for maxi-
mum utilization with minimum main-
tenance. The articulated pistons are
made to last 30% longer, and also give
30% longer life after the engine’s first
rebuild. Oil seals have been engineered
so they are never exposed to contami-
nants.
The MT5010 is equipped with an
air-conditioned ROPS/FOPS- appro-
ved cabin with forward-facing seat and
back-up video monitor, and has an active
hydraulic suspension system for im-
proved operator comfort and handling.
Indeed, Stawell operators report that
the MT5010 suspension is the most com-
fortable in their experience and pro-
vides a much softer, smoother ride. They
observe that, when working 12-hour
shifts, this makes a huge difference. The
cab is also set up for efficient operation,
with good driver visibility, clear instru-
ments, and all controls easy to reach.
One of the most noticeable and impres-
sive features of the MT 5010 truck is its
power. The Cummins engine delivers
torque of more than 3,000 Nm through
the six-speed automatic transmission.
From a standing start under load it pulls
extremely well, whereas vehicles from
the previous fleet struggled. It also has
500m
1500m
1000m
Stawell Gold Mines
MINERALISED SYSTEM
Longitudinal Projection December 2004
0 SCALE 500m
RESERVE BLOCKS
INDICATED RESOURCE BLOCKS
INFERRED RESOURCE AREA
MINED AREA
GOLDEN GIFT DOMAINS
EXPLORATIONS TARGET
BASALT
PORPHYRY
FAULT BLANK
S N
Getting the ore out at Stawell involves an incline of 1:8 to the 400 m level and then 1:10 to surface.
One of the four MT5010 mine trucks at Stawell Mine with manager Bill Colvin and driver Bruce Mclean.

a tight turning circle, saving on backing
out trucks in the limited space under-
ground, and is a lot less tedious to
drive, being much faster than the old
machines.
The engine on the MT5010 is elec-
tronically controlled for maximum fuel
efficiency, minimum exhaust emissions
and continuous diagnostic monitoring.
This control system, along with an elec-
tronic transverter, provides smooth and
precise gear changes.
In addition to the selection of Cum-
mins as the engine supplier, Atlas Copco
has put the MT5010 through a series of
more than 40 performance-enhancing
upgrades to the engine, powertrain, cab,
suspension, structural body, and systems,
which dramatically increase engine and
component life. Servicing is fast and
simple, thanks to easy access to filters,
test points, and other parts which re-
quire regular maintenance.
Continuous support
The routine performed by the mine’s
maintenance team includes checking
main functions after each 12-hour shift,
as well as more thorough services at 125
hours, and the recommended intervals
at 250 hours.
The MT5010 trucks, despite their
arduous working situation, are acknow-
ledged by Stawell management as being
the best performing trucks on site, with
the highest t/km and excellent availabil-
ity. As a result, the MT5010 trucks now
constitute 70% of the hauling fleet.
Where problems have been experi-
enced, the mine knows it can rely on
support from Atlas Copco.
If they need a part, or a question an-
swered, Atlas Copco provides a true,
24-hour service, seven days a week, and
treats every enquiry with the correct de-
gree of urgency.
A technical training course on the
MT5010 was conducted at the mine by
Atlas Copco to further enhance the ex-
pertise of the maintenance staff. Many
of the participants reported back that
it was the best on-site training they had
ever received from any equipment sup-
plier, observing that Atlas Copco under-
stands that aftermarket service and sup-
port is an important complement to any
sale.
Future plans at Stawell include fur-
ther exploration and deeper development
work. In the next four to five years it is
planned to increase the mining depth to
at least 1,300 m.
Acknowledgements
agement and staff at Stawell mine for
their assistance in the production of
this article.
The Minetruck MT5010 exits from the Stawell portal after a 9 km uphill drive.

Fax: +46 19 670 7393
Working with Atlas Copco means working with world-leading
products and services. What’s more, the people you work with
are the best – with the ability to listen and to understand the
diverse needs of our customers. This approach requires experi-
ence and knowledge, presence, flexibility and involvement in
their processes. It means making customer relations and service
a priority.
Through interaction, innovation and a continuous drive to im-
prove the way we do things – we help our customers achieve
results.

Woomera, south australia
Geology
The Olympic Dam mineral deposit
consists of a large body of fractured,
brecciated and hydrothermally altered
granite, a variety of hematite-bearing
breccias and minor tuffs and sediments.
The breccia lies under 300-350 m of
barren flat-lying sediments comprising
limestone overlying quartzite, sandstone
and shale. The deposit contains semi-
discrete concentrations of iron, copper,
uranium, gold, silver, barium, fluorine
and rare earth elements. These are scat-
tered throughout an area 7 km-long and
4 km-wide, and having a depth of over
1,000 m. There are two main types of
mineralization: a copper-uranium ore
with minor gold and silver within nu-
merous ore zones, making up most of
the resource; and a gold ore type which
occurs in a very restricted locality.
There is distinct zonation evident
throughout the deposit, ranging from
iron sulphide (pyrite) at depth and
towards the outer edges of the deposit,
through to copper-iron sulphides and
increasingly copper-rich sulphides to-
wards the central and upper parts of the
deposit. The zonation can continue with
rare native copper through to gold-
enriched zones, and finally into silici-
fied lithologies. Uranium occurs in
association with all copper mineraliza-
tion. The predominant uranium mineral
is uraninite (pitchblende), but coffinite
and brannerite occur to a lesser extent.
Virgin rock stress conditions are
comparable in magnitude with most
Australian mines, with the principal
stress horizontal and approximately 2.5
times greater than the vertical stress,
due chiefly to the weight of overlying
rock.
With few exceptions related to weaker
areas, the workings are generally dry.
In-situ rock temperatures range from 30
to 45 degrees C.
Mine programme
The Olympic Dam mine comprises under-
ground workings, a minerals processing
plant, and associated infrastructure with-
in a mining lease area of 29,000ha.
Situated 80 km north of Woomera, and
560 km north-north-west of the South
Australia state capital of Adelaide, the
mine has sufficient estimated reserves
for a possible life of 70 years within cur-
rent rates of production, although the
actual mine plan is in place for only 20
years at present. The mine has its own
purpose-built town, Roxby Downs, lo-
cated 16 km away. There are around 980
employees, of which 490 work in mi-
ning, and there are also 400 contractors
on site.
Access to the mine is through a 4 km
long surface decline and three shafts:
the Whenan shaft, which was the origi-
nal exploration access, converted for
hoisting; the Robinson shaft, sunk in
1995; and the new Sir Lindsay Clark
shaft.
The last completed expansion stage
results from a feasibility study carried
out in 1996 that recommended an
expansion of ore output from 3 million
t/year to 9 million t/year. The facilities
for this expansion were completed in
Sublevel stoping at Olympic
Dam
Rapid expansion
Since discovery of the massive
Olympic Dam orebody in 1975,
and the establishment of the mine
in 1988, the complex has been
through a series of rapid expan-
sion programmes. Owned and op-
erated by BHP Billiton, it is the lar-
gest single underground mine in
Australia, with a production rate of
30,000 t of ore per day to produce
around 185,000 t of copper product
annually and significant quantities
of uranium, gold and silver. Total
mineral resource underground is
3,810 million t grading 1.1% copper
and 0.4 kg/t uranium oxide. The
mine’s staged expansion has been
run in parallel with a philosophy of
continuous improvement of mi-
ning methods. They employ a fleet
of Atlas Copco Simba rigs for down-
hole production drilling within a
carefully planned and controlled
sublevel stoping method of pro-
duction.
Tasmania
Victoria
Perth
Melbourne
Darwin
Hobart
Brisbane
Sydney
Canberra
Western
Australia
Northern
Teritory
Queensland
New South
Wales South Australia
Adelaide
OLYMPIC DAM
Coober
Pedy
Lake Eyre
North
Lake Eyre
South
Lake
Torrens
Port
Augusta
Woomera
Olympic Dam location in South Australia.

1999 at a cost of Aus$1,940 million.
They included an automated electric
rail haulage system (based on that at
the LKAB Kiruna mine), a new under-
ground crusher station, a third haulage
shaft (the Sir Lindsay Clark), a substan-
tial increase in ventilation capacity, a
new smelter, and an enlarged hydromet-
allurgical plant. The Sir Lindsay Clark
shaft is fitted with the largest mine win-
der in Australia, both in terms of power
(6.5 MW) and hoisting capacity (13,765
t/h). These facilities increased the an-
nual production capacity to 200,000 t
of refined copper, 4,300 t of uranium
oxide, 75,000 oz (2.33 t) of gold and
850,000 oz (26.44 t) of silver.
Further expansion under the Optimi-
sation Phase 3 plan in 2003 increased
copper production to 235,000 t/year.
Since 1988, more than 100 km of un-
derground development has taken place
to facilitate the production of more than
17 million t of mined ore. As of Decem-
ber, 2000, ore reserves were predicted
to be 707 million t, with average grad-
ing of 1.7% copper, 0.5 kg/t uranium
oxide, and 0.5 gm/t gold.
The mine’s revenue is made up from
sales of copper (75%), uranium (20%)
and gold and silver (5%). Copper cus-
tomers are based in Australia (26%),
Europe (16%), northern Asia (28%) and
south-east Asia (30%). Uranium is sold
to the United States (54%), Japan (23%),
Europe (22%) and Canada (1%).
Mining method
A carefully sequenced and monitored
method of sublevel open stoping is em-
ployed to extract the ore. This was chosen
chiefly on the basis of: the depth of the
orebody and volume of overburden; the
large lateral extent of the orebody; the
geotechnical attributes of the ore (see
above), the host rock and barren materials,
as well as their geological distribution;
the grade and volume of the ore; the
mine’s production requirements.
This type of mining is most suitable
for large ore zones that are character-
ized by relatively regular ore-waste
contacts and good ground conditions.
At Olympic Dam, the method features
the development of sublevel drives, us-
ually at 30-60 m vertical intervals.
From these sublevels, a 1.4 m-diameter
raise hole is excavated by contracted
raise boring. This extends the whole
vertical extent of the designated stope.
Production blastholes of 89-155 mm-
diameter are then drilled in ringed fans,
or rows parallel to the ore limits. Plan-
ning engineers, in consultation with the
drill-and-blast engineer, develop the
patterns using the Datamine Rings soft-
ware package. The normal hole para-
meters are 3 m overburden and 4 m toe
spacing.
A powder factor of 0.25 kg of explo-
sives per tonne of ore is generally main-
tained. Blasts range in size from about
500 t, when opening an undercut slot, to
250,000 t for the maximum stope ring
firing. There are six to ten blasts/week.
Charging is carried out by two 2-man
crews, working 14 shifts/week. Firing is
World ranking of Olympic Dam mine
Metal Resource ranking Production ranking % of world production
Copper No.5 No.17 1.4%
Uranium No.1 No.2 11%
Olympic Dam mine exploration.

carried out by a remote initiation system
using an electromagnetic field link con-
trolled by PEDCALL software from a
desktop computer. Called BlastPED, the
system has improved the reliability and
safety of blasting. The maximum trans-
verse width (across strike) and length
of the stope have been determined as 60
and 35 m respectively.
The stope length (along strike) is ge-
nerally based on mineralization, geolo-
gical discontinuities, and other geotech-
nical issues such as in-situ stress distri-
bution, possible stope geometry and
stope filling. The stope crowns are
generally domed to maximize stability.
Perimeter drives are located a minimum
of 1.5 m away from stopes.
The stopes are laid out by mine de-
sign engineers in consultation with the
area mine geologist, and then presented
to the operating personnel. This is in-
tended to gain formal approval from
underground production, development
and services departments, so providing
a forum for continuous improvement. A
final document incorporating any re-
commendations is then issued, so that
everyone is aware of the agreed stope
development procedure and all relevant
data such as drill-and-blast design lay-
outs, firing sequences, ground support
designs, backfill design, ore grades,
structural controls, and ventilation se-
quencing.
Extraction and filling
WMC employs Atlas Copco Simba
4356S electro-hydraulic rigs for down-
ward blasthole drilling, whilst upholes
are avoided as much as possible. Mining
usually commences at one end of the
stope, and from one sub-level to the
next, until the stope is completed. Once
DUMPING
MUCKING
TRAMMING
Extraction
Drive
STOPE
STOPE
UNDERCUT
DRAWPOINT
DRAWPOINT
LOADER
EXTRACTION
DRIVE
STOPE TRUCK
HAULING
TO ORE PASS
LOADER
TRAMMING TO
ORE PASS 250 M AWAY
EXTRACTION DRIVE
EXTRACTION DRIVE
MOBILE ROCK
BREAKER
ORE PASS
GRIZZLY
FINGER PASS
GRIZZLY
TRUCK DUMPING
INTO FINGER PASS
GRIZZLY
ORE PASS
TO TRAIN LEVEL
EXTRACTION
DRIVE
LOADER TRAMMING
TO ORE PASS GRIZZLY
Activity overview showing mucking, tramming and dumping of ore from a typical stope.
Activity Overview Mucking Overview
Tramming Overview
Dumping Overview

drilling is complete, the stope is fired
in stages to ensure maximum fragmen-
tation and minimum dilution of ore.
First the slot is formed around the raise-
bored hole, and then subsequent blasts
peel away the ore into the void. Suffi-
cient broken ore has to be removed by
loader from the bottom sublevel of the
stope at the footwall to allow for swell-
ing of the rock and the next firing
stage.
The extraction process continues in
this way, and then all broken ore is re-
moved leaving a roughly rectangular
prism-like vertical void, which is then
backfilled. The broken ore is transferred
to one of the permanent, near vertical,
orepasses linking the extraction levels
with the rail transport level. These load
minecar trains, which carry the ore to
the underground crusher and shaft hoist
system.
The optimum geotechnical dimen-
sions of the unsupported open stope are
usually insufficient for complete extrac-
tion of the suitable ore at that position,
so a series of secondary, and maybe
tertiary, stopes have to be developed
adjacent to the primary stope. This ne-
cessitates a substantial structural fill for
the primary stope, to ensure the struc-
tural security of the adjacent stopes
without leaving a pillar. This comprises
a cement aggregate fill (CAF) produced
Secondary
Primary
Unmined
Tertiary
Unmined
Unmined
Unmined
Unmined
Unmined
Unmined
Unmined
Unmined
UnminedSecondary
PrimaryDesigned stopes
Primary stope extracted
CAF filled due to unmined adjacent stopes
CAF fill
ROCK fill
CAF fill
ROCK fill
2nd Primary stope extracted
CAF filled due to adjacent unmined stopes
Secondary stope extracted
Tertiary stope extracted
Secondary stope extraction
ROCK filled as no adjacent stopes
ROCK fill
CAF fill
CAF fill
Stope extraction and filling sequence.
550 m B.S.L.
650 m B.S.L.
520 m B.S.L.
450 m B.S.L.
570 m B.S.L.
TRAIN LEVEL
SURGE BIN
FINGER PASS
FINGER PASS
ORE PASS
400 m B.S.L.
Loaders and Trucks dump ore
into the Ore Pass Grizzly's.
The Grizzly is essentially a large
steel grate designed to stop
large rocks getting into the ore pass.
These large rocks are broken up
by a Mobile Rock Crusher.
Ore slides down the ore passes
into the Surge Bin.
The Ore is loaded onto the Train.
The Train continues to the Crusher,
dumps the ore which is crushed
and hauled to the surface
36 tonnes at a time.
FINGER PASS
GRIZZLY
Ore progression from stope to train level.

on site. Later stopes, which are not cri-
tical in geotechnical terms, can be re-
stored more economically with uncon-
solidated rock fill, or a combination of
both.
Other factors determining the use of
CAF include planned future develop-
ment within the stope, and/or a need for
a tight fill to the crown of the stope.
Since CAF forms a substantial pro-
portion of the mining costs, mine devel-
opment plans usually try to minimize
the size of primary stopes in favour
of larger secondary stopes, which use
unconsolidated fill.
This is particularly important in
areas where the orebody is relatively
narrow. If the primary stope is not
filled with CAF, and adjacent stopes
are then required, a pillar, gener-
ally 10 m-wide, is left between the two.
Additional support of the stope crown
may be required, and this is carried out
by cable bolting. This is also used to
reinforce drawpoints.
Careful sequencing of the stope ex-
traction programme is an important
feature of mining at Olympic Dam, for
economical mining and minimal ore di-
lution. The sequence is determined by
several factors, including ventilation
capacity to remove radon gas and other
contaminants, the grade and tonnage
requirements of the mill, and the prox-
imity of any unfilled stopes. The XPAC
Autoscheduler computer software pack-
age has been introduced to improve the
efficiency of the sequencing process.
Pride of Simba rigs
Atlas Copco has had a fleet of Simba
4356S machines at Olympic Dam since
1992, and has had a service contract
on site supporting and maintaining the
fleet since 1994. The machines consist-
ently achieve high levels of productivity
and availability at a minimal cost. The
Simba rigs are predominantly used to
drill downhole production blast holes
for the stopes. Their average mechani-
cal availability is 88-92%, and they drill
between 8,629 m and 9,359 m/month.
Drill-and-blast methods are also used
for main drive developments, and for
roof bolting as necessary, or in the
rehabilitation of old mining areas re-
entered.
Olympic Dam mining and production statistics
Description Amount
Underground development drives (2000) 1,100 m/month
Producing stopes each month (2000) 24
Average stope size (2000) 300,000 tonne
Average stope production rate (2000) 30,000 tonne/month
Average stope production time Ten months
Average stope filling time One month
Average stope fill curing time Three months
Copper production (2002) 178,523 tonne
Uranium Oxide production (2002) 2,890 tonne
Gold production (2002) 64,289 oz
Silver production (2002) 643,975 oz
Simba 4356S longhole drill rig with COP 4050 tophammer rock drill.

Load-haul-dump (LHDs), wheel
loaders and a trucking fleet, as well as
the automated rail haulage system, make
up transport system at the mine. The rail
system transports ore from surge bins
to an underground crusher. A computer
located in a central control room con-
trols all operations. After crushing to
around 150 mm, ore is hauled in 36 t
skip buckets to the surface ore-blending
stockpile for processing.
Mine planning
Extensive site investigation, analysis of
rock properties, and computerized plan-
ning and control procedures aid mine
management in the most efficient ex-
ploitation of reserves. The programmes
are discussed at meetings with relevant
line managers to be agreed or modified,
before implementation.
As geotechnical conditions are so im-
portant for stope stability, the materials
properties of the intact rock have been
determined from more than 200 labora-
tory tests. A three-dimensional model
of estimated Uniaxial Compressive
Strength (UCS) has been developed
for the resource area. Evaluation of
drill core logs indicates that the mean
structural spacing is greater than 6 m,
so the general rock mass condition can
be regarded as ‘massive’. Jointing is also
uncommon, but some faults have been
identified. The most significant have
sericite filling of 10 mm size. Conti-
nuous natural structures that may reduce
excavation predictability are increasing-
ly being digitized for further analysis.
A new process is being used to transfer
geological data to 3-D digital models.
The mine development schedule in-
cludes the sequencing of stope develop-
ment, but is also based on a combination
of copper and uranium grades, copper/
sulphide ratio, ventilation, and orepass
use. Ventilation is particularly impor-
tant, as current underground mining
practices are primarily governed by suf-
ficient ventilation resources to handle
radon. Other air contaminants are heat,
diesel fumes and dust. Each ventilation
district, including its own intake and ex-
haust (return) air routes, has the capac-
ity to operate two to four producing
stopes at a time.
A five-year production schedule is
evolved in a spreadsheet format using
the area stoping sequence. This is used
as the basis for scheduling other mine
activities. The operations department
carries out short-term scheduling on a
three-month rolling basis.
More expansion ahead
The Optimisation Phase 3 expansion
programme was carried out over three
years to 2006, looking at mining fac-
tors such as: loader performance; stope
design; fragmentation and productivity;
rail haulage reliability and interfaces;
and exploration to improve ore quality
and optimize infrastructure.
Studies of options for further expan-
sions to Olympic Dam’s operations are
underway in 2007, due to exploration
work indicating that the orebody will
support a doubling of output. This will
help meet future long-term global de-
mand, which has expanded significantly
over the past few years. An open pit mine
is the current preferred option to achieve
the proposed capacity increase because
of the scale of the orebody. However,
a two-year prefeasibility study includes
the examination of a broad range of al-
ternatives, with expansion planning
split into five key stages to be carried
out over a 7-year period to production
ramp-up.
Acknowledgements
Atlas Copco is grateful to BHP Billiton
and the management at Olympic Dam
mine for their kind assistance in the
preparation of this article.
Intake Raise
Intake Raise
Ore Pass
Slot Raise
Internal
Exhaust Raise
Exhaust Raise
Intake air
Exhaust air
Typical stope ventilation flow layout.

NANJING, CHINA
Late starter
China began to stake a claim on the in-
ternational mining map at the start of
the 1990s, with a determination to in-
troduce mechanization, coupled with a
strong desire for reform and commer-
cial success. Today, more than ten years
later, Chinese mines are reaping the
benefits that modern mining equipment
and methods can bring.
Shanghai Baosteel Group Corpora-
tion, a state-owned company set up in
1998, has an iron production of 20
million t/y. Amongst its suppliers is
Meishan iron ore mine, one of its sub-
sidiaries.
Meishan is widely regarded as a mo-
del mine by the Chinese iron ore indus-
try, and the equipment and methods it
uses, most of which are supplied by Atlas
Copco, are constantly being monitored
and adopted by others around the coun-
try.
Situated on the Yangtze River Delta,
some 320 km from Shanghai, Meishan
is the second largest underground fer-
rous metals mine in China, with raw
ore output of 4.25 million t in 2006,
reflecting a steady increase of 10%
each year.
The Meishan orebody, which is more
than 100 m below the surface, is 1,370 m-
long and 824 m-wide. It has a maximum
Meishan mine portal.
Rocket Boomer 281 at Meishan.
Improved results at Meishan
iron ore mine
Bright future
China is rich in natural resources,
and is already the fourth largest
gold producer in the world. This
vast country has abundant depos-
its of copper, lead, zinc, iron and
other minerals, not to mention
huge reserves of coal, oil and gas.
As more mines adopt mechaniza-
tion, China’s potential as a world-
class mining nation continues to
grow. An operation that typifies
the trend in productivity and effi-
ciency improvements is the
Meishan underground iron ore
mine, near Nanjing. Having been
a limited producer for many years,
Meishan is now showing signifi-
cantly improved results, thanks to
enlightened management, backed
by Atlas Copco equipment.

NANJING, CHINA
thickness of 292.50 m and a minimum
thickness of 2.56 m, giving an average
thickness of 134 m. The deposit is esti-
mated to contain reserves of 260 million t
of predominantly Fe3O4 iron ore.
The mine entrance is located 37 m
above sea level (ASL), where the first
phase of development got underway in
1975, and the ore is currently mined at
-243 m ASL.
Development
Phase One of the Meishan development
plan comprised shaft development, un-
derground stoping and sub-level caving.
There are six shafts, three for hoisting
(main, secondary and southwest), and
three for ventilation (south, southeast
and west). The main ramp, built in
2000, is connected at its lower end to
the horizontal mining area at the -198
m level. The mining process consists
of development drifting, rock drilling
for stoping, back-stoping and recovery,
transportation, and ore hoisting, in which
Meishan has pioneered the introduction
of mechanization.
In this respect, the mine has been
working hand in hand with Atlas Copco.
It installed its first Atlas Copco Simba
H252 drill rig in April, 1993, and now
operates 11 Atlas Copco rigs. Of these,
three Simba H252, one Simba H254
and two Simba H1354 rigs are used for
production drilling, while four Boomer
281 and one Rocket Boomer 281 are
used in development. In addition, two
Scooptram ST1020 loaders are employed
on production.
The Simba rigs drill 76 mm blast
holes, while the Boomer rigs drill 76 mm
cut holes and 48 mm blast holes. All
drifting and medium-to-long hole dril-
ling is carried out by Atlas Copco drilling
rigs. This equipment has been instru-
mental in enabling Meishan to con-
tinuously improve its productivity and
efficiency, year on year.
For example, from 1995 to present,
the number of workers employed in drif-
ting has been successively reduced from
more than 500 to 160, and the number
of miners has also diminished signifi-
cantly. During the same period, produc-
tivity has been substantially increased
(see table).
Meishan is in operation approxima-
tely 300 days/year, and drifting and mi-
ning teams comprise two men per drill
Wagner service truck doing the rounds of the mine.
Idealized long section of mine.
Southwest
ventilation
Southeast
ventilation
North
ventilation
Shaft for
personnel hoist
1# Main shaft 2# Main shaft
+31.50 m +37 m
–186 m
–198 m –198 m
–213 m
–228 m
–243 m
RAMP
+47 m
–258 m
–330 m
–447 m

NANJING, CHINA
rig, six hours/shift, two shifts/day. The
Boomer 281 drills for one cycle each
shift, with a 3 m advance, while the
Simba H252 achieves 120-140 m/shift.
By the end of 2006, annual produc-
tion for the Simba H252 and Simba
H254 was 60,000 m/rig, and the Simba
H1354s were producing 72,000 m/rig.
The capacity of the Boomer 281 was
1,700 m of drifts, and 1,900 m for the
Rocket Boomer 281, in faces 5 m-wide
and 3.8 m-high.
Long partnership
With more Atlas Copco equipment co-
ming on stream, productivity will be
successively increased to meet new,
ambitious targets for the next phase of
development.
According to its plans for Phase Two,
mining will proceed down to a level of
-420 m, and annual output will be in-
creased to 4.2 million t of ore. The dis-
tance between the levels will be also be
increased, from 15 to 20 m.
Through its long partnership with
Atlas Copco, Meishan has also accumu-
lated extensive experience of equipment
management and maintenance, where
the focus is on spot checks for clean-
liness, lubricating, oil refilling, and
greasing. Atlas Copco service engineers
provide technical support, assisting on
scheduled maintenance and repairs, and
spare parts forecasting and stock plan-
ning. These combined efforts have led
to equipment availability close to 100%.
In addition, as Meishan is a showcase
of Atlas Copco’s after sales service,
training for other customers’ operators
often takes place at this location.
Excavation equipment managers at
the mine state that, during more than
10 years of working with Atlas Copco,
they have been consistently provided
with equipment of correct design with
flexibility in operation, low energy con-
sumption, high reliability, low pollution
and long service life.
Excellent after sales service, and an
abundant supply of spare parts, can now
be taken for granted.
Acknowledgements
Atlas Copco is grateful to the directors
and management of Meishan Iron Ore
Mine for their assistance in the produc-
tion of this article, and to Baosteel Group
Corporation for permission to publish.
Control panel on Rocket Boomer 281.
Simba production drill rig, one of six at Meishan.
Production and equipment build up at Meishan
Year 1999 2000 2001 2002 2003 2004 2005
Development cu m 100,315 109,149 109,536 129,600 115,200 126,770 312,510
Number of drill rigs 4 4 4 5+1 backup 6+1 backup 6+1 backup 5+2 backup
Output of iron ore (Mt) 2.84 3.18 3.33 3.46 3.87 4.00 3.91
Drill metres (x1,000 ) 203 248 350 380 375 290 280
Number of employees 1,640 1,540 1,500 1,420 1,460 1,420 1,410

We understand what you’re after
Committed to your superior productivity
Fax: +46 19 670 7393
www.atlascopco.com
Working with Atlas Copco means working with highly pro-
ductive rock drilling solutions. It also means sharing a common
cost-cutting challenge. Like you, we are always looking for new
and effective ways to squeeze your production costs – but never
at the expense of quality, safety or the environment.
Mining and construction is a tough and competitive business.
Fortunately, we understand what you’re after.

Rustenburg, South Africa
Thin seam, high output
Waterval Mine is near Rustenburg, about
150 km northwest of Johannesburg. It is
one of Anglo Platinum’s newest mines,
and will be making its contribution to
the group’s target by excavating 3.2 mil-
lion t/year in an orebody just 0.6 m-thick
and on a decline of nine degrees.
Despite the low seam and restricted
mining space, Anglo Platinum was con-
vinced that it could tackle the task suc-
cessfully, and opted for the room and
pillar method with ramp access, to-
gether with mechanized equipment.
The mine design meant that the
rooms would be extremely confined,
with a height of 1.8-2.0 m. This, in turn,
meant that headings would have to be
as low as possible, and the equipment
extremely compact. Anglo Platinum also
insisted that quantum improvements be
made at the mine in three priority areas:
safety, production and productivity, in
that order. Potential suppliers were asses-
sed by Waterval engineers. Atlas Copco
was the only company able to provide
a total solution around the three key
mining tools required: loader, drill rig,
and bolting rig. These needed to be
low profile, compact and technically
advanced, specially designed for low
seam work and exacting environments.
In addition, Atlas Copco agreed to act
as a cooperation partner in all aspects
of the rock excavation process, providing
operator training, spare parts supply, and
service and maintenance.
Room and pillar layout at Waterval where Scooptram ST600LP loaders work in as low as 1.8 m headroom.
Mechanized mining in low
headroom at Waterval
Boosting production
The Anglo Platinum Group of South
Africa, the world’s leading plati-
num producer, has completed an
ambitious plan to boost its annual
output by 75% from 2.2 million
ounces to 3.5 million ounces by
the year 2006. This tough target
would have been a daunting pros-
pect for most mining companies,
especially in conditions at its
Waterval mine, where headroom
seldom exceeds 2.0 m. However,
Anglo Platinum, which accounts
for more than half of the total plat-
inum produced in South Africa,
has very extensive experience of
low seam operations. This expe-
rience led the company to Atlas
Copco, who supplied a complete
equipment package to Waterval’s
specification to meet all of its low
headroom loading, drilling, and
rock bolting needs.
Scooptram ST600LP in the stopes.

Rustenburg, South Africa
Purpose matched package
The equipment trio comprised the Atlas
Copco Scooptram ST600LP loader, the
Rocket Boomer S1 L drill rig, and the
Boltec SL bolting rig. The units were
progressively delivered to Waterval, un-
til there were 23 Scooptram ST600LP
loaders, 15 Rocket Boomer rigs, and six
Boltec units at the site.
The Scooptram ST600LP, also
known as the Ratel, is a compact LHD
with a height of around 1.5 m. It has a 6
t loading capacity, and is equipped with
a special bucket for low height work. It
is powered by a clean burning 136 kW
Deutz diesel engine.
The Rocket Boomer S1 L has well-
proven, heavy duty Atlas Copco compo-
nents such as the COP 1838 rock drill,
BUT 28 boom and BMH 2837 feed.
The Boltec SL is a high production,
semi-mechanized rock bolting rig with
an electrical remote control system.
Apart from standard rockbolt instal-
lation, it is also equipped to perform
long hole drilling for anchor and cable
bolting. The Boltec SL uses the same
carrier as the Rocket Boomer S1 L,
bringing advantages of commonality.
The equipment complement for each
mining section is one Rocket Boomer,
one Boltec, and two Scooptram ST600LP
loaders.
Production drilling
The layout at Waterval is divided into
12 sections with nine panels, or stopes.
Each panel averages 12 m-wide x 1.8
m-high, with pillars of approximately
6 m x 6 m. The drillers work three 8 h
shifts per day, six days a week and their
target per section is 23,000 t/month.
That translates to 200 t per panel, or two
panels per shift. Some 68-74 x 3.4 m-long
holes are required in each panel, taking
around 2.5 h to drill. Three 77 mm holes
form the cut, and the main round is dril-
led using Atlas Copco Secoroc model
–27 R32 43-45 mm bits.
Ramps from the surface provide the
access for men, machines and supplies,
and also accommodate conveyor belts
for transporting the ore out of the mine.
The mine expects each Rocket Boomer
rig to yield around 200,000 t/year. For
rockbolting, 1.6 m-long Swellex bolts
are used, in a standard bolting pattern
of 1.5 m x 1.2-1.5 m. The Boltec SL is
equipped with Secoroc Magnum SR28
Tapered Speedrods, with 38 mm model
-27-67 bits for Swellex installation. The
tramming height of the Boltec SL is just
1.30 m, with ground clearance of 0.26
m. It is equipped with a COP 1028HB
rock drill, and can insert a Swellex bolt
of length up to 1.6 m in roof height of
1.8 m.
With so many available faces in close
proximity to each other in the room
and pillar layout, utilization is a key
factor for maintaining a high level of
productivity and efficiency. The required
utilization for the drill rigs ranges from
50%-75%, and availability is about
90%.
Low height loading
The Scooptram ST600LP is an extre-
mely robust loader designed specifically
for demanding thin seam applications
where the roof heights are as low as 1.6
m. For visibility on the far side of the
machine, video cameras point to front
and rear, displaying the views on a screen
in the driver’s cab. Loading from the
different rooms is a crucial part of the
operation, and the specially designed
E-O-D (Eject-O-Dump) 6 t-capacity
bucket on the Scooptram ST600LP
makes low height work easy. Using the
E-O-D bucket, the rock is pushed out by
a push plate onto feeders that transfer
it to the conveyor system for transpor-
tation to the surface. The Scooptram
loaders are refuelled underground and
generally drive up to the surface for
maintenance.
At Waterval, Anglo Platinum gives
top priority to dilution and utilization.
The amount of rock waste must be kept
to an absolute minimum, and the fact
that this can be achieved with mecha-
nized equipment in such a low, flat seam
is seen as a major achievement.
To ensure high availability of the
equipment, Anglo Platinum and Atlas
Copco have entered into full-service con-
tracts that provide for 24 h service and
maintenance. It makes good business
sense for the mine to have a service
contract manned by specialists with the
technical know-how and skills for opti-
mal maintenance.
Acknowledgements
ment at Waterval for their kind assist-
ance in revision of this article and for
permission to publish.
Roof bolting in low headroom.

KGHM, Poland
Geology and resources
The Legnica-Glogow copper basin ex-
tends over an area of 416 sq km. The stra-
tiform mineralization occurs where Per-
mian limestone lies against New Red
Sandstone, within varying combinations
of sandstone, shale and dolomite. The
deposit is of irregular shape, with slight
dip up to about 6 degrees. The copper
content varies generally between 1.2%
and 2.0%. Higher copper contents are
characteristic for the thinnest seams,
usually in mineralized shales.
In the Lubin mine the average copper
content is less than 2%, whereas in the
Polkowice-Sieroszowice mine, the mean
copper content slightly exceeds 2%. The
average copper content for all KGHM
mines is around 1.86%. The ore horizon
ranges from 1.2 m to 20 m in thickness,
lying at depths of between 600 m and
1,200 m from surface. Known ore re-
serves are above 800 Mt, which corre-
sponds to a mine life of another 30 years
at today’s production rate of 28 Mt
annually, split between Lubin 7Mt,
Polkowice-Sieroszowice 10Mt, and
Rudna 11Mt.
Lead, silver and gold are also recov-
ered. In 2001 KGHM was ranked as the
world’s seventh largest copper supplier
at 491,000 t, and the second largest
source of silver, at 1,145 t.
KGHM is also a major salt producer,
using roadheaders to mine a deposit that
partly overlays the orebody.
Geotechnical conditions
The formations are intersected by a
multitude of faults. An especially dan-
gerous feature of the rock is its ability
to accumulate high amounts of energy,
which is the most important factor for
rock burst. Even within a strong roof,
in some places weak layers of shales
essentially decrease the roof bearing
capacity. This is the main reason for
extensive rock reinforcement, compris-
ing standard mechanical and resin
grouted 1.6 m and 2.6 m bolts, and 5-7 m
cable bolting, mainly at drift crossings.
Ore access and transport
The deposit is developed with 26 ver-
tical shafts, 6 m to 7.5 m-diameter,
and horizontal drifts. Depths of shafts
vary from 632 m in Lubin to 1,120 m
in Rudna. The overburden freezing
method was applied for shaft sinking.
Access to the deposit from the shafts
and preparatory workings is by drift
networks located directly under the
strong dolomite roof and upon the sand-
stone, along the dip of the ore zone.
Mucking is based on a large fleet of
LHDs ranging from 1.5 to over 8 cu m
bucket capacity. Belt conveyors are used
for main haulage. Equipment used in
the shafts varies, and depends on the
One of four Scooptram ST1520LP loaders owned by KGHM in operation.
Large scale copper mining
adapted to lower seams
Efficient
commercialization
Copper mining began in the 13th
century in the Sudety Mountains.
However, intensive exploratory
works beginning at the middle of
the 20th century confirmed a cop-
per ore-bearing deposit 1,000 m
below surface with over 0.5% Cu
content. The first mines, called the
Old Basin, are now closed and re-
placed by mining of the New Basin,
known as Legnicko-Glogowski
Okreg Miedziowy, LGOM, situ-
ated in the south-west region of
Poland. It is based on three big
mines with various dates of con-
struction start: ZG Lubin (since
1960), ZG Rudna (since 1970) and
ZG Polkowice-Sieroszowice (since
1996). The latter mine results from
joining of the former single mines:
ZG Polkowice (since 1962) and ZG
Sieroszowice (since 1974). All mi-
nes belong to a joint-stock com-
pany, KGHM Polska Miedz S.A.,
with head office in Lubin, and
comprising ten divisions including
three dressing plants, two smelt-
ers and one copper rolling mill.In
the ten years between 1991 and
2001, when commercialization of
the former state owned company
was undertaken, the company
workforce reduced from 45,000 to
about 18,500. About 11,500 emplo-
yees are engaged in the mining
operations.

KGHM, Poland
purpose of the shaft. The most modern
shaft in Rudna mine is Koepe hoist eq-
uipped with two twin-skip hoisting
installations. Each of the skips has 300
kN capacity and 20 m/s transportation
velocity. The depth of the loading level
is 1,022 m. Each skip is powered by a
four-line hoisting machine with 5.5 m-
diameter transmission using 3,600 kW
motors.
Room and pillar
The predominant method is room and
pillar mining adapted to seam thickness
and geotechnical conditions.
Deposits up to 5 m-thick
After shaft sinking and recognition of
the water threat, the initial mining me-
thod utilized backfilling technology.
Following this, longwall methods using
walking hydraulic supports, armoured
face conveyors and belt conveyors were
introduced. Very soon, after experien-
cing low efficiency, it was decided to
use room and pillar methods with bolt-
ing techniques, and LHDs that could
assure mass production and better out-
put concentration. With time, and pro-
duction experience, room and pillar
methods with roof caving have become
more effective and safer, since they en-
abled full mechanization to be intro-
duced. The caving methods were more
competitive, due to low costs compared
to backfilling techniques. Initially, for
the exploitation of roof caving, two
stages of excavating pillars were used. In
the first stage, the area was divided into
25 m x 35 m pillars. In the second stage,
each of the pillars, beginning from the
abandoned line, was cut into many
smaller pillars. From the viewpoint of
rockburst risk, the two-stage method is
System for mining thick deposits.
General mining layout for 3 m thickness at Polkowice-Sieroszowice Mine.
7m
7m
7m14m
Backfill module
Timber post
~21 m² area
3 m
Thickness of
mineralized
zone
Room Pillar
Dry backfill
~ ~
~
~ ~ ~ ~ ~
~ ~
~ ~
~ ~
~
~ ~ ~ ~ ~
~ ~
~ ~
~ ~ ~ ~
~ ~ ~ ~
~~~~
A-A
B-B
C-C
A A
B B
C C
14 m 14 m 14 m
7m
7m
7 m
7 m
14m
14 m
7 m 7 m 7 m 7 m
7 m10 m4 m 7 m 14 m
7 m 7 m 14 m
4m10m
B
B
A A
4m6m4m
4 m 10 m
D
D
C C
5m5m5m
5 m 10 m
A-A
10m
75˚
8m
60˚
C-C
B-B D-D
10m
75˚
12m
60˚
7m
9,5m
10M

KGHM, Poland
tricky, because the pillars in the first
stage show a dangerous tendency for
accumulation of energy. After 1983, the
engineers in Rudna mine decided to
adapt the dimension of the pillars to
local geomechanical conditions. Also,
alternating directions of driving stopes
were introduced.
Deposits 5 to 7 m-thick
Until recently, the deposits over 5 m-
thick used to be mined entirely with
backfilling. The newest technology to
7 m-thick is based on the hypothesis of
advance-fracturing and post-failure
capacity of pillars. The roof opening
reaches 150 m, and the longest edges of
the pillars are located perpendicular to
the exploitation front line.
Within caved areas, the upper layers
of roof are not fully supported with bro-
ken rock. Such a situation creates real
threat of rock bursts, roof falls, or lo-
cal relief of strata. This results in ore
dilution, as well as a requirement for
secondary scaling and bolting. There-
fore, the practice of blasting residual
large-size barrier pillars has been aban-
doned.
Deposits below 3 m-thick
In the Polkowice-Sieroszowice mine,
most of the seams are less than 3 m thick,
and a special selective mining method
has been developed for excavation of
these thin deposits.
The mining area is typically opened
using double or triple entries of prepara-
tory workings. Rooms, entries and pil-
lars are basically 7 m-wide. Work in the
faces consists of two phases, depend-
ing upon the thickness of the layers of
waste rock and mineralized ore. First,
the upper ore-bearing layer is excavated
and hauled out to special chutes onto
the main transportation system. In the
second phase, the waste rock adjacent
to the floor is excavated and placed in
other rooms as dry fill. Each of the en-
tries covers at least two rows of pillars
plus one room.
The backfill width is 14 m, and ma-
ximum length of the mining front is
about 49 m. No more than three rows
of pillars at the same time, not cove-
red with backfill, are allowable in the
mining area. During extraction in the
last row of pillars, working occurs only
in the ore-bearing layer until the pillar
cross-section reaches approximately
21 sq m. The completion of the pillar
mining process before abandoning the
area is subject to roof sag, with the strata
resting upon dry backfilled entries.
The future aim is to use extra low
profile mechanized equipment for drill-
ing, bolting, mucking, scaling, charging
and auxiliary transport. This will enable
mining in drift heights down to 2 m and
1.5 m, to selectively extract the ore and
minimize the amount of waste rock
mined.
Alternative mining sequences, where
the ore-bearing layer is situated at the
floor, are shown in the figure.
In the past, most equipment and con-
sumables were manufactured in nearby
factories belonging to the state-owned
company. Lately, the quantities and
types of imported equipment have grad-
ually increased. In 1998, Polkowice-
Sieroszowice Mining Department
started to cooperate with Atlas Copco
in the development of modern machin-
ery. Due to the successful introduction
of COP 1238 and COP 1838 hydraulic
rock drills, followed by the low-built
Boomer rigs, the cooperation has been
strengthened. The mine currently oper-
ates ten Atlas Copco rigs, and there is
a total of 16 Boomers on the mines as
a whole.
The supplier service has been ex-
tended to include a drillmetre-based
contract for Secoroc Magnum 35 drill
rods and shank adapters and for COP
rock drills.
Working an effective 4.5 h/shift, one
Boomer drills 110-125 holes with hole
lengths varying from 3 m at the face
and 1.5-2 m at side walls and roofs.
Some of the Boomers feature the BSH
110 rod extension system to facilitate
drilling of 6 m stress-relieving holes.
In the first 8 months of 2002, one
Boomer drilled more than 58,000 holes
totalling 174,000 drill metres, with
availability of 92.6 %. Downtime com-
prised technical malfunctions 3.7%,
planned service 3.4%, and others 0.3%.
Room and pillar mining with roof sag
This method is especially suitable in
barrier pillars of drifts, heavily faulted
zones, and in direct vicinity of aban-
doned areas. Maximum allowable de-
posit dip is up to 8 degrees, and seam
thickness 3.5-7 m. The area is developed
Two-stage extraction with backfilling.
1-6˚
1 5 3 2 4
6
1. Back fill 2. Upper layer,extraction 3. Lower layer extraction
4. Ramp to lower layer 5. Water collector 6. Back fill piping

KGHM, Poland
with double gate roads, located close
to the roof of the ore-bearing layer for
thickness above 4.5 m. Optimum length
of the mining front ranges from 50 m
to 600 m. The ore is extracted with 7 m-
wide and 7 m-high rooms. The roof is
supported by pillars of 7-10 m x 2.5-
4.5 m. Thereafter, the smaller pillars
are successively decreased. The roof
that has been opened must be bolted
immediately.
The next stage is mining of the floor
down to the ore zone boundary. The
extracted area is closed off for people
and equipment, using timber posts or
chocks. Length of the roof sag blast
holes is 8-12 m.
Room and pillar mining
–two stage mining
The two stage mining system using hy-
draulic backfill known as Rudna 1 has
been used mainly in the Rudna mine.
In the first stage, the orebody is cut into
large pillars, which are subdivided in the
second stage.
Finally, the abandoned area is filled
up to the roof with hydraulic fill. The
drawback of this system is high stress
concentration occurring in the large
size pillars just in front of the second
stage mining.
Blasting techniques
In the past, the mines tried to use dyna-
mite, which is a water-resistant explosive
of high density and energy concentra-
tion. Due to the sensitivity to detonation,
and lack of possibility for mechanical
charging, dynamite is today almost
completely superseded by pneumati-
cally charged ANFO. Initiation is by
electric delay detonators, coupled with
detonating cord in holes longer than 6 m.
Recently, electric detonators have been
successively replaced by Nonel. Bulk
and emulsion explosives are used in
room and pillar mining areas described
in the hydraulic backfill method above.
Future plans
The alternative room and pillar mining
methods described are some examples
from a large variety of adaptations to
prevailing geological and geotechnical
conditions, in order to continuously in-
crease productivity and safety, while
minimizing waste rock into the ore
stream. The following measures are put
into focus for the future: further devel-
opment of the rock mass monitoring
stream; changes in work organization
and introduction of a four-team system;
developing new systems for rockburst-
proof bolts; introduction of low built
equipment for thin ore deposits, lower
than 1.5 to 2 m; modernization of mi-
ning methods by further minimizing
waste dilution; and projects for access
to deeper ore zones, below 1,200 m, by
cake mining, with cake thickness of 0.8
to 1.5 m, using 15 m-long blast holes.
All mines are facing thinner seams,
and this constitutes a major challenge
for equipment manufacturers. The prob-
lem is especially acute at Polkowice-
Sieroszowice, where machinery height
since 2003 on all types of equipment
cannot exceed 1.4 m, to enable efficient
operations in 1.6 m-high workings. To
this end, a special low-built version of
the latest Atlas Copco Rocket Boomer
S1LP has been delivered for testing and
evaluation.
Acknowledgements
Atlas Copco is grateful to KGHM ma-
nagement for their inputs to this article,
and in particular to the authors of its
book on the technical evolution of the
Polish copper mining industry:
Jan Butra, Jerzy Kicki, Michal Narcyz
Kunysz, Kazimierz Mrozek, Eugeniusz
J Sobczyk, Jacek Jarosz, and Piotr Sa-
luga. Reference is also made to Under-
ground Mining Methods – Engineering
Fundamentals and International Case
Studies by William A Hustrulid and
Richard L Bullock, published by SME,
details at www.smenet.org
Room and pillar mining with roof sag.
A B
A -B
200-600m Pillar in yielding phase
Pillar size 7 - 8 x 8 -38 m
Residual pillars
Atlas Copco drill rigs and loaders delivered to KGHM
Type Units
Boomer S1 L 5
Rocket Boomer S1 L 26
Rocket Boomer 281 SL 4
Scooptram ST1520 6
Scooptram ST1520LP 4

Germany/South Korea
Case studies
The major characteristic of a success-
ful underground mining operation is its
efficiency, and the single greatest factor
affecting this is the cost of drilling and
blasting. Atlas Copco drill rigs are
bringing down this cost by a combina-
tion of drilling speed and accuracy
with low maintenance and longevity.
Matching the drill rig to the job ensures
that, whatever the mining situation,
economic long-term production can be
achieved, sometimes with the whole
operation dependent upon a single ma-
chine. The following case studies from
four very different locations serve to
underline this point.
Auersmacher, Saarland,
Germany
Since 1936, almost 20 million t of lime-
stone have been produced at Auers-
macher, a border town in Saarland,
Germany. The mining area covers al-
most 4 sq km, with overburden of ap-
proximately 50 m in thickness and an
average mining height of some 6 m. The
Triassic strata comprises a shelly lime-
stone, which is excellently suited as an
aggregate for the local steel industry.
The mine is working a room and
pillar system of extraction in the hori-
zontal deposit, and the normal face is
5 m-high and 6.5 m-wide. The length
of a room plus pillar is about 100 m, in
which some limestone is left to form the
permanent roof.
A diesel-powered computerized
Atlas Copco Rocket Boomer L1C-DH
hydraulic drill rig is used because there
is no electricity supply installed to the
faces. It is equipped with a COP 1838
rock drill with 22 kW output. As a re-
sult, blast holes of 51 mm diameter can
be drilled to depths of 3.4 m at a rate
of 6-8 m/min. Each V-cut round of 35
holes produces up to 340 t, and takes
only an hour to drill.
The Rocket Boomer L1C-DH rig
drills the entire daily production output
in a single shift, returning very favour-
able operating and wear costs. Mine
output is currently 350,000 t/year, for
which the rig is drilling six rounds on
each dayshift. The rest of the mine works
two 8 h shifts/day, 5 days/week on pro-
duction, with a Saturday morning shift
for non-production work if required.
Experience with the diesel hydraulic
unit has shown it to be economic on fuel,
and to exhibit low exhaust gas emis-
sions.
The Rocket Boomer L1C-DH diesel
engine consumes only about 19 litres
of dieseline for each percussion drill-
ing hour, and can complete two shifts
on a single tank of fuel. The excellent
exhaust emission values are very impor-
tant in underground mining, where ven-
tilation can be costly. Due to the very
good drilling and flushing characteri-
stics using water mist, drill rod losses
are negligible. Water consumption varies
Underground mining of limestone
and gypsum
Trading costs for
profit makes mining
more attractive
Limestone in its various forms is
in such great demand, both as
high quality roadstone and as the
raw material for cement and steel
manufacture, that its mining is fre-
quently carried out underground.
Gypsum is needed as an additive
to the cement-making process,
and is also a major input to build-
ing plaster and plasterboard pro-
duction.
Closeness to the market, or
availability of a suitable mineral
deposit, may be the driver, but eco-
nomic extraction is the deciding
factor. In essence, the underground
limestone and gypsum mines are
trading off the savings in surface
transportation costs by being clo-
ser to the point of use, against the
marginal difference in production
costs between surface and under-
ground working.
Where these are approxima-
tely in balance, an underground
mine can be profitable, as the
following examples show. In all
cases, Atlas Copco drill rigs are the
key to economic success.
Rocket Boomer L1 C-DH drilling the face at Auersmacher limestone mine.

Germany/South Korea
from 2-5 lit/min depending upon rock
conditions, and a full tank lasts a week.
The water mist mix is adjusted by the
operator. With too little water, it is im-
possible to drill, and with too much, the
cuttings become slurried.
The rotation speed has a profound
effect on penetration rate. In the lime-
stone rock at Auersmacher, the opti-
mum speed is 400 rev/min. Dropping it
to 300 rev/min reduces the penetration
rate by 2 m/min.
Drilling is carried out exclusively with
Atlas Copco shank adapters and drill
rods, and the very good dampening and
anti-wear properties have resulted in
enormously long service lives, despite
the high work capacity. For example,
the approximate service life of drill bits
is 3,200 m, rods 10,000 m, and shank
adapters, 18,500 m.
Secoroc shank adapters and steels
are used with 51mm ballistic bits. A
couple of years ago the mine switched
from 42mm bits, achieving a 2 m/min
improvement in penetration rate, with
accompanying gains in ANFO blast
yield.
At the start of each drilling shift the
operator takes around 15 minutes to
check the engine oil, feed hoses and
grease points. His training as a mechanic
helps him to get the best out of the so-
phisticated engine. The servicing re-
quirements have no negative impact on
mine production.
High temperature greasing of the
rock drill gearbox is carried out every
40 hours, or once a week.
The close support of the Atlas Copco
team has resulted in a collaborative re-
lationship that gets the best out of the
equipment.
Obrigheim,
Neckarzimmern, Germany
Heidelberg Cement employs some 37,000
people at 1,500 sites in 50 countries, a
truly international company with sales
in excess of EUR6.6 billion.
Since 1905, the company has been
operating an underground mine in
Obrigheim producing gypsum and an-
hydrite. This operation is only possible
thanks to the use of percussion drilling
technology provided by an Atlas Copco
computerized Rocket Boomer L1C drill
rig introduced in 2003. Training for ope-
rators covering drilling, systems and
maintenance was provided by Atlas
Copco, leading to excellent results and
high utilization.
Production is by room and pillar, with
10 m-wide x 5.5 m-high drives. A 4.5
m-deep round comprises four cut-holes
of 89 mm-diameter and 60 blastholes
of 45 mm-diameter. Much work has
been put in by both the mine and Atlas
Copco to optimize the drill pattern to
maximize the pull of each round.
The rig is equipped with a heavy duty
COP 1838HF rock drill, and hydraulic
systems and onboard compressor are
driven by a 75 kW electric motor. The
diesel engine is used to move the rig
around the mine. A water tank with
water admixture device provides the
flushing medium for drilling.
Penetration rates vary considerably
due to the large range of compressive
strengths of gypsum and anhydrite,
Veiw from the driver´s seat of the Rocket Boomer L1 C-DH.
Rocket Boomer L1 C drilling 4.5 m-long blastholes at Obrigheim.

Germany/South Korea
which are spread over 10-130 Mpa. A
45 mm-diameter hole, 4.5 m-long is
drilled in 40-75 seconds. The computer-
ized drilling log has recorded an aver-
age penetration rate of 3.23 m/min,
including cut holes.
Of the 300,000 t/y mine output, some
90% goes to the cement industry, with
the remainder used by the Neckarzim-
mern gypsum plant for plaster manu-
facture.
Josefstollen, Trier,
Germany
Josefstollen mine was opened in 1964
and produces some 600,000 t/y of raw
dolomite primarily for the building ma-
terials industry. Operating company
TKDZ has some 40 million t of reserves
at its disposal, enough for another 40
years of mining.
The dolomite is of excellent quality,
with a compressive strength of 130-150
Mpa, and optimized underground pro-
duction allows the products to be placed
on the market at competitive prices.
Mining is by conventional room and
pillar at two gallery levels in the bottom
and central beds. The production area
is initially opened up by mining hori-
zontal galleries, with ramp access to the
individual beds. Room widths are 5 m
in the bottom bed and 5.5 m in the cen-
tral bed, with heights of 5.0-5.5 m.
Each blasting round comprises 29
off 3.3 m-deep x 45 mm-diameter
holes with a Vee cut. Around 13 faces/
day must be drilled to keep pace with
demand.
Drilling is carried out by a diesel-
hydraulic Rocket Boomer L1 C-DH rig
equipped with COP 1838HF rock drill
and air-water mist flushing. The rock
drill takes around 25-30 seconds to
drill each hole, at a penetration rate of
8 m/min. Total drilling time is about 30
minutes for each round.
The dolomite is difficult to drill be-
cause it is not a continuously compact
formation, so the computerization on
the drill rig, which controls both the
hammer and feed, plays a vital role. As
a result, most of the required drilling
is completed on a single shift, with the
second shift offering flexibility for drill-
ing awkward places and for performing
maintenance. The mine also sees this
slack time as a reserve against any in-
creased production demand.
Yongjeung, Jechon, Korea
Yongjeung limestone mine is situated in
Jechon city in the Choongbook province
of South Korea, some 150 km southeast
of capital city Seoul.
The strata is a middle limestone mem-
ber of the Gabsan formation in the upper
palaeozoic Pyeongan super group of
minerals. The geological structures are
mainly controlled by a NW-SE trend-
ing, with westerly overturned folds and
thrust faults.
Reserves confirmed by drilling are
over 12 million t, of which it is expected
Rocket Boomer L1 C-DH with COP 1838HF rock drill achieves 8 m/min at Josefstollen.

Germany/South Korea
that over 5.5 million t will eventually
be mined. Average chemical analysis of
the limestone bed is CaO 54.4%, SiO2
0.78%, MgO 0.53%, Al2O3 0.03%, and
Fe2O3 0.17%.
Around 25,000 t/month of limestone
is produced for markets that include
companies operating plants for the
manufacture of desulphurization prod-
ucts, quicklime, calcium carbonate and
chicken feed.
The limestone bed is mined in three
steps, starting with 15 m-wide x 7 m-
high room and pillar, followed by a 9 m
bench. A Rocket Boomer L1C-DH diesel
powered drill rig is the main production
machine in the room and pillar faces,
drilling 4 m-long x 51 mm-diameter
holes. Generally, 50 holes are drilled in
each face, and three faces are drilled in
each 8 h shift. This affords a capacity
of 3,000 t/day or 70,000 t/month. When
drilling, the rig’s diesel engine operates
for around 1 min/drilled metre, con-
suming 0.31 litres of fuel. Returns from
rig consumables are: rods 975 m; bits
750 m; shanks 3,900 m; and sleeves
1,950 m.
An Atlas Copco ROC D5 crawler rig
is used for downhole drilling of the
bottom bench. This rig has a long fold-
ing boom which allows the operators to
drill at a comfortable 5.5 m from the
edge of the crater, a major improvement
over the previous pneumatic rigs, which
needed to be within 2 m of the edge.
Conclusions
Where there is no suitable electricity
supply to the mining areas to power an
electro-hydraulic rig, as at Auersmacher
and Yongjeung, diesel-driven hydraulic
rigs offer a means of upgrading mining
efficiency without excessive capital
expenditure. At these mines, drilling
rates doubled with the introduction
of the Rocket Boomer L1C-DH, and
round depths increased significantly.
These machines, equipped with water
tanks and water mist flushing, operate
efficiently despite the absence of mains
supplies of water and electricity. They
are also adaptable, performing on both
production and development, and han-
dling rockbolt and ancillary drilling.
Production and efficiency gains have
been recorded wherever the Rocket
Boomer L1C-DH has been introduced,
making it a boon to mines where every
penny counts.
Acknowledgements
ments at Auersmacher, Heidelberg,
TKDZ and Yongjeung for their inputs
to this article and for permission to
publish.
Vertical benching of bottom parts
Pillar
Pillar
7 m
9 m
Principle mining method at Yongjeung.
Rocket Boomer L1 C-DH on demonstration at Yongjeung limestone mine. Atlas Copco ROC D5 drilling the bench at Yongjeung.

Campo Formoso, Brazil
Underground geology
Located in the city of Andorinha, around
100 km from the Pedrinhas mine, the
company’s underground operations have
been developed within the Medrado/
Ipueira deposit.
This is one of several chromite-min-
eralized intrusions in the Jacurici Valley
in the north-east of the São Francisco
Craton, which hosts Brazil’s largest
chromite deposits. Being irregular and
fractured with numerous faults, the de-
posit presents a considerable geological
and mining challenge.
The Medrado/Ipueira deposit is di-
vided into several mining areas. There
are the Medrado mine and the Ipueira
mine, the latter of which is divided into
five working areas: Ipueira II, III, IV,
V and VI. Currently, besides Medrado,
only Ipueira II, III, IV and V are opera-
tional, whereas Ipueira VI is a future
expansion project. The underground mi-
nes have been in steady operation since
1977. In 2004, Ipueira produced 450,000 t
of run-of-mine ore for a final produc-
tion of 127,000 t of hard lump. In the
same year Medrado produced 192,000 t
of ROM ore for a final production of
48,000 t of hard lump. Current target
is a total of 216,000 t of hard lump.
Underground exploration
The company is always looking for the
best way of doing things in consultation
with workers, technical consultants and
through visits to other mines. The con-
sultation process also includes manufac-
turers of mining equipment, with which
Ferbasa discusses the best technological
options for its operations. This consulta-
tion process is very important for the
mine, in order to help maintain a high
level of modernization.
From a geological point of view, the
Medrado/Ipueira orebody represents a
challenge. With an average thickness of
8 m, and 500 m-long panels, the orebody
is irregular and fractured with numer-
ous faults. The accurate delineation of
the orebody is very important, and to
this end the geology department has to
carry out a great deal of exploration
drilling. The main machine employed in
this key task is an Atlas Copco Diamec
U6 exploration drill rig equipped with
an operator’s panel. This machine is
used in all situations at the underground
mine, to drill holes of up to 150 m-deep.
The decision to acquire this machine
took into account the fact that it is eq-
uipped with a wire line system. This
feature makes possible to conduct core
drilling in the worst rock conditions,
such as the faulted and fractured rock
at Ferbasa.
Ferbasa carries out about 7,200 m/y
of drift development. The fleet of deve-
lopment rigs includes two Atlas Copco
electro-hydraulic units. One is a Rocket
Boomer H 252 rig equipped with COP
1238 rock drill which drills 3.9 m-long
holes to achieve 6,000 drilled metres/
month at a productivity of 55 m/hour.
There is also a Rocket Boomer M2 D
rig equipped with COP 1838ME rock
drill which drills 4.5 m holes to achieve
12,000 drilled metres/month at an aver-
age rate of 70 m/hour.
Sublevel caving
The main underground mining method
employed is longitudinal sublevel ca-
ving, though open stoping is also used
in some areas of Ipueira, depending on
the layout of the orebody. When the ore-
body is vertical, sublevel caving is used
Sub level caving for chromite
In search of
excellence
Cia de Ferro Ligas da Bahia (Fer-
basa) is a private capital group,
which produces chromite, silicon
and limestone. One of Brazil’s most
important metallurgical compa-
nies, Ferbasa has surface and un-
derground mining operations in
the state of Bahia in north-eastern
Brazil, where their Pedrinhas open
pit chrome mine, located in Campo
Formoso, has been in operation
since 1961. Pedrinhas currently pro-
duces about 2,400,000 cu m/year
of chromite ore and waste, yielding
54,000 t/year of hard lump chro-
mite and 114,000 t/year of chro-
mite concentrate. At the Medrado
and Ipueira underground mines,
lump chromite is produced using
primarily sublevel caving techni-
ques with raises opened using slot
drilling, where a fleet of Atlas
Copco equipment offers key sup-
port in exploration, development
and production.
Entrance to the Ipueira mine.

and, in the few cases when the orebody
is horizontal, open stoping is the pre-
ferred method. Both methods are safe,
with currently acceptable dilutions.
However, the management has started
looking for suitable alternative methods
that will reduce the dilution in future.
For longitudinal sublevel caving, produc-
tion drifts are developed in the footwall
of the orebody. The vertical distance
between sublevels varies from 14 m to
30 m. Production drilling is upwards,
using a fan pattern. The broken ore is
loaded using LHDs, and is hauled from
the production levels to the surface
using rigid frame trucks.
In terms of production, the company
drills 180,000 m/year of production
blast holes, which have a diameter of
51 mm and a burden of 2.2 m. At the
same time, they are studying the pos-
sibility of changing to 76 mm-diameter
holes and 2.8 m burden, in order to re-
duce costs.
The fleet of production drill rigs in-
cludes an Atlas Copco Simba H254 and
a Simba 253, both electro-hydraulic
Layout of Ipueira mine.
N 55
N 65
N 75
N 85
N 95
N 105
N 115
N 125
Production loading
Charging – production holes
Production drilling
Mucking out
Charging
Scaling
Drilling
Shot
creting
DevelopmentProductionThe locations of drifts and drill patterns are adapted to the ore-waste boundaries.
Ore
Waste
Drift
Cable
Blast holes
2.2 m

rigs equipped with COP 1238ME rock
drills, which drill 6,000 m/month to
achieve a productivity of 22 m/h. The
mine also has a Promec M195 pneu-
matic rig equipped with COP 131EL
rock drill. These machines are also used
to drill orebody definition holes, and
achieve 3,500 m/month.
Slot drilling
One of the main challenges at Ferbasa’s
underground operations is the develop-
ment of inverse drop raises. These open-
ings, which are also called ‘blind raises’
because they don’t communicate with
the upper level, can only be accessed
from the lower level. This limitation is
dictated by the mining methods.
Previously these blind raises were de-
veloped upwards by successive individual
advances of up to 6 m. Nowadays, this
practice has been replaced with a fully
mechanized method, increasing the
speed and safety of drilling the open-
ings. Looking for a solution to improve
operator safety when drilling these pro-
duction raises, technical personnel from
Ferbasa visited LKAB’s Malmberget
iron ore mine in Sweden, where they
studied the development of inverse drop
raises blasted in one single shot. After
the visit, Ferbasa started employing a
slot drilling technique, and Ipueira and
Medrado are now the most experienced
mines in Brazil in its use. Slot drilling
requires a row of 7.5 in -diameter inter-
connected holes to be drilled using a
special guide mounted on a regular ITH
drill hammer. Thus, with an available
free face, drilling accuracy, and con-
trolled blasting techniques, openings
of up to 25 m length are successfully
achieved. The main advantages of the
method are personnel safety and speed
in the drilling. Also, slot drilling is
more precise and, in general, more
productive.
A Simba M6 C drill rig equipped with
COP 64 DTH hammer and ABC Regular
system, as well as an on-board booster
compressor, has been acquired for drill-
ing inverse drop raises with holes up to
10 in-diameter. Depending on the length
of the raise, and the quality of the rock
mass, the slot drilling technique is used.
If the length of the raise is short, and
the rock quality poor, the traditional
technique with reamed holes is used.
Until the Simba M6 C arrived, Fer-
basa was carrying out slot drilling with
only one machine. They chose the new
Simba rig because of its advanced tech-
nological and safety features. One of the
main advantages is the setup, which
only has to be carried out once at each
site.
The Simba M6 C machine is also easy
to operate, and the spacious, air-condi-
tioned cabin is an attractive feature.
The mine spent five years looking for
a solution to the opening of inverse drop
raises, and is pleased with its invest-
ment in technology and modernization
represented by the Simba M6 C.
Acknowledgements
ments at both Ipueira and Medrado
mines for their contributions to this
article.
Slot drilling at Ferbasa: The Simba M6 C in action and, (right), the perfectly finished row of holes.
The slot drilling crew with their Simba.

www.atlascopco.com/cmtportal
When you choose Secoroc DTH equipment, you decide what balance of technol-
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Secoroc has the broadest range of hammers, bits, and related equipment of any
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ceivable applications.
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of DTH solutions

Zacatecas, Mexico
Mechanization pioneer
The official name of the Proaño mine
comes from Captain Diego Fernandez
de Proaño, who discovered the site and
developed the first mining works on the
hill that bears his name. The operation
is also known as Fresnillo mine because
of its proximity to Fresnillo city. It is
run by the Compania Fresnillo, SA de
CV, which is 100% owned by Peñoles.
With a history that can be traced as far
back as the 1550s in Pre-Hispanic times,
Proaño has gone through a number of
phases, which have left an important
mark on the mine. Its operations have
been stopped due to economical and
technical difficulties (1757 to 1830), as
well as during the Mexican Revolution
(1913 to 1919), and inevitably it has gone
through several ownership as well as
technological changes.
From employing basic manual tools
in the early days, the mine now employs
modern mechanized units, including
some of the most sophisticated mining
machinery available.
Embracing mechanization early on
has been one of the factors that has hel-
ped Proaño cement its position as the
world's largest and most profitable silver
mine. They started mechanizing opera-
tions about 40 years ago, and during the
last 30 years there has been a steady
increase in production. Products are
silver-lead concentrates and silver-zinc
concentrates. In 2005, Proaño produced
nearly 34 million troy ounces, or 1,055 t,
of silver.
Production expansion
During the mine's long history it has
had to adapt to changes in the geology
and work parameters. For instance, the
mining method has had to be funda-
mentally changed several times, and
each time the appropriate technology
and equipment has had to be introduced.
Atlas Copco has worked alongside the
mine management for several years to
adapt and innovate with primary equip-
ment, service, training, inventory man-
agement and parts stock. The mine re-
cently implemented a substantial pro-
duction increase, going from 4,500 t/day
to 7,000 t/day. To support this produc-
tion expansion the company recently
increased its mining fleet with the pur-
chase of three Rocket Boomer 281 de-
velopment drill rigs additional to its
four existing units, another Simba M4 C
production drill rig additional to its ex-
isting three units, five Scooptram ST1020
loaders to complement its existing fleet
of 17 units, and two Minetruck MT2000
trucks to increase its fleet to seven units.
Atlas Copco has also started a service
contract for the Simba rigs, which re-
quires the presence of four technicians
on site, and offers similar assistance for
the loaders.
Currently, the Proaño mining fleet
represents a mix of old and new Atlas
Copco technology. Amongst the old units
are Scooptram ST6C loaders, BBC 16
pneumatic rock drills, BMT 51 pusher
leg rock drills and DIP DOP pneu-
matic pumps. There are also Diamec U6,
Diamec 262 and Diamec 252 explora-
tion drill rigs, Boltec 235 bolting rigs,
Rocket Boomer 104 drill rigs, Simba
1254 production drill rigs and Robbins
Getting the best for Peñoles
Special operations
Industrias Peñoles’ Proaño and
Francisco I Madero mines are very
special operations. Both under-
ground mines, Proaño is a 450
year-old operation and the richest
silver mine in the world, and FIM
is just six years old and the larg-
est zinc mine in Mexico. Located
in the central state of Zacatecas,
both mines are key users of Atlas
Copco equipment, which includes
Scooptram loaders and Minetrucks.
Peñoles has decided to standardize
its whole mining fleet on Atlas
Copco equipment to obtain maxi-
mum benefit from the service
and distribution centre in nearby
Caleras.
Setting up Simba 1254 for blast hole drilling.

Zacatecas, Mexico
raise borers. Furthermore, the mine uses
Secoroc drill steel on development and
production rigs.
Proaño was the first mining opera-
tion in Mexico to employ the Boltec rigs
and the Rocket Boomer 281 rig with
telescopic advance, which represent
completely new technology.
Likewise, Proaño owns two Diamec
U6 APC deep hole drill rigs, the first
mine in the Americas to use this type
of machine.
During the first three months of 2006,
the entire Atlas Copco mining fleet at
Proaño achieved a physical availability
of 89.5% against the objective of 90%.
Atlas Copco's commitment with
Proaño goes beyond providing new
equipment, and a few years ago it was
decided to set up a distribution ser-
vice centre in Caleras, Zacatecas.
Mining operations
The underground operations can be ac-
cessed either through two shafts, Central
Shaft and San Luis Shaft, or by one of
the mine's several ramps. The mine has
seven levels and in Level 425 is the San
Carlos orebody, which currently pro-
duces 67% of production.
Proaño carries out about 40,000 m
of development drilling a year. To sup-
port this work, there are three different
contracting companies: Mincamex, Jo-
margo and Mecaxa. All three compa-
nies own Atlas Copco equipment,
mainly Rocket Boomer drill rigs and
loaders.
The mining method is cut fill using
upwards and downwards drilling. How-
ever, the amount of drilling and the hole
diameter have changed over the years.
M E X I C O
GUATEMALA
BELIZE
HONDURAS
EL SALVADOR
USA
G U L F O F M E X I C O
G
ulf
of
C
a
lifo
rn
ia
Mexico City
Madero Mine
Atlas Copco Mexicana
(Tlalnepantla)
Proaño Mine (Fresnillo)
Zacatecas
Atlas Copco Distribution
Service Centre
(Caleras)
Map of Mexico showing Atlas Copco bases and mine locations.
Schematic of mine layout at Proaño showing sublevel stoping arrangement.

Zacatecas, Mexico
They went from drilling 20 m down-
wards and 10 m upwards to drilling
22 m downwards and upwards. Then
changes in the orebody allowed use of
long hole drilling employing Simba rigs
with top hammers.
The base main level is serviced with
electricity, water and air, from where
the sublevels are supplied. Currently,
the miners drill 25 to 32 m downwards
and 25 to 32 m upwards, using a com-
puterized Simba M4 C DTH rig from a
single set up.
This method provides better safety,
higher productivity and lower costs.
Community environment
The expansion of the Fresnillo city
through the years means that Proaño's
operations are now situated almost in-
side the city. The company has taken
this fact as an opportunity to develop a
good relationship with the community.
In order to diminish the environmental
impact of its operations, the company
has invested in the installation of en-
vironmentally friendly equipment and
machinery. Proaño has an ISO 14000
Environmental Management System
certification and has also been awarded
a Clean Industry Registration by the
Mexican environmental authority.
Furthermore, the company has foun-
ded an ecological park, which is a sanc-
tuary for several species of mammals,
birds and reptiles. Nearby, there is also
a tourist mine, and a mining museum
to make the public familiar with the mi-
ning process and to preserve the history
of the industry. In 2004 the company
opened the Parque los Jales, a public
area that includes lakes, paths and
open areas for physical exercise and re-
laxation. This facility was built on the
land formerly occupied by the tailings
pond.
New operation
Located about 15 km north of the city of
Zacatecas, Francisco I. Madero (FIM)
is one of Peñoles' newest mines, having
started commercial production only in
2001. The mine's name comes from a
former Mexican President, Francisco
Ignacio Madero, killed during the Mexi-
can Revolution. Although a polymetallic
mine with reserves of gold, silver, cop-
per, lead and zinc, FIM's main products
are zinc concentrates and lead concen-
trates. At the end of 2005, the mine had
reserves of 27.5 million t with an ave-
rage zinc grade of 3.3% and 0.74% of
lead.
With an investment of US$125.8 mil-
lion and a production capacity of 8,000
t/day, in 2005 FIM produced a total of
65,948 t of zinc concentrates and during
the first semester of 2006, produced
31,572 t. The mine is equipped with a
radio system for internal and external
communication through a network of
coaxial cables in the production levels,
development areas and mining infra-
structure. This system incorporates
voice, data and video channels for com-
munication between personnel, accident
reduction, production control and loca-
tion of vehicles and personnel.
Atlas Copco started working with
the Peñoles' team in charge of the FIM
1500
380o
750750
4600
4915
Drilling possibilities offered by Simba M4 C.
Rocket Boomer L2 C drill rig with COP 1838 rock drills at Madero mine.

Zacatecas, Mexico
project in October, 1997 and has con-
tinued to provide technical support in
the planning and development of the
mine. The first order from the mine was
for four Rocket Boomer L1 C and three
Rocket Boomer L2 C drill rigs with
single and twin booms respectively.
These rigs, which have enclosed, air
conditioned cabs, feature ABC Regular
computerized drilling system with com-
munication ports and protocols for PC,
failure and anti jamming systems. FIM
also ordered eleven Scooptram ST8C
loaders with weighing system, real time
communication system via leaky feeder
to a control centre, and auto-diagnostic
system with data port. The first machines
arrived in 2000.
This initial fleet has subsequently
been expanded to include: two Robbins
raise-borers, a 61R and a 63RM; three
SB 300 scalers; a Craelius Diamec U6
exploration rig; a Simba production
drilling rig; and two Boltec 235 bolting
rigs.
Furthermore, Atlas Copco Mexicana
and FIM have an important mainte-
nance contract, which has been running
for six years. This is the largest such con-
tract that Atlas Copco has in Mexico,
and comprises a team of around 20
people including mechanics and super-
visors, directly supported by their Ca-
leras distribution service centre.
According to the management at
FIM, the Atlas Copco equipment has
contributed to the rapid and safe ad-
vance in production at this mine.
FIM mining operations
For development and production work,
FIM employs several contracting com-
panies, amongst which are Minera Ca-
stellana, which also carries out explo-
ration work. Contractors Arconso and
Paniagua Obras Mineras both conduct
development work.
The latter has a specific contract to
conduct at least 200 m/month of devel-
opment work using an FIM Rocket
Boomer L1 C rig equipped with COP
1838 drill and one of the Scooptram
ST8C loaders. Around 235 m of devel-
opment has been achieved in a month.
The Scooptram ST8C loader operator
is very happy with the machine, which is
the most modern equipment he has wor-
ked to date. He finds the controls easy,
and had no problem learning to drive.
Because of the generally poor ground
conditions, FIM employs cut fill with
pillars as its mining method. It has been
the method of choice since operations
started. It opens voids of 8 to 10 m,
bounded by non-recoverable pillars of
6 m in a square section. It has a mineral
recovery factor of 86% to 90%.
For production, horizontal and
vertical drilling is used in a ratio of
30%:70%, but that will change by
mid-2007 to 100% long hole drilling
angled 75 degrees upwards. The roof is
expected to be subjected to less damage,
and less support should be needed. The
risk of rock falls is also much lower.
This is similar to methods used at
Proaño, so their experience will be most
useful.
FIM uses a mixture of shotcreting
and bolting, and recently acquired two
Boltec 235 roof bolters with COP 1532
drills. Each machine regularly installs
nine roof bolts per hour, or 56 per shift.
Depending on the quality of the rock, up
to 70 bolts/shift have been installed.
On average, about 2,400 bolts/month
are installed. Tests at the mine prior to
purchase of the Boltecs revealed that
the bolts were each taking 17 t loading.
Most of the mined material is un-
loaded by gravity directly to a crushing
station.
The rest of the production is hauled
in 40 t-capacity trucks in a closed
circuit of horizontal haulage on the
general haulage level, located at 210 m
from surface.
A conveyor belt is installed in a 4 x 3
m ramp with an inclination of 21% and
a length of 1,290 m from level 2022 to
the surface.
For personnel access, mining equip-
ment and general mining services, there
is a 4.6 x 4 m ramp with an inclination
of 13.5% and 1,790 m length between
surface and the general haulage level.
Maintenance
To deliver its maintenance contract,
Atlas Copco has its own facilities at
the mine, backed up by the distribution
and service centre in Calera. The con-
tract includes preventive and corrective
maintenance, and follows a programme
already prepared for all the Atlas Copco
fleet.
The service contract has a specific
programme every week depending on
the machines to be serviced. About 50%
of the machines have been working for
between 18,000 and 20,000 hours with-
out any rebuild, which is a good refer-
ence for the quality of the equipment.
The contract also involves operator
training.
Acknowledgements
Atlas Copco is grateful to the mine ma-
nagements at Proaño and Madero and
directors of Peñoles Group for their
inputs to this article and for permission
to publish.
Personal service at Proaño: left, Antonio Gonzales, mine captain, San Carlos area, with
(far right) Rufino Molina, Atlas Copco drill master and Simba rig operators.

Barroca Grande, Portugal
Introduction
The Panasqueira mine is located at Bar-
roca Grande in a mountainous region of
Portugal, 300 km northeast of the capi-
tal city of Lisbon, and 200 km southeast
of the port city of Porto.
The mining concession lies in mod-
erately rugged, pine and eucalyptus co-
vered hills and valleys, with elevations
ranging from 350 m above sea level in
the southeast to a peak of 1,083 m above
sea level in the northwestern corner.
The concession area is an irregular
shape trending northwest-southeast, and
is approximately 7.5 km-long. It is 1.5
km-wide at the southeastern end, and 5.0
km-wide at the northwestern end, where
the mine workings and mill facilities
are located. The geology of the region
is characterized by stacked quartz veins
that lead into mineralized wolfram-
bearing schist. The mineralized zone has
dimensions of approximately 2,500 m
in length, varying in width from 400 m
to 2,200 m, and continues to at least
500 m in depth.
Production levels
Access to the mine’s main levels is by
a 2.5 m x 2.8 m decline from surface,
with a gradient of 14%. The main levels
consist of a series of parallel drives that
are spaced 100 m apart, and which pro-
vide access to the ore passes for rail
transport, and connect with ramps for
movement of drilling and loading equip-
ment.
There are seven veins between the 2nd
and 3rd Levels, which are 90 m apart.
The veins are almost flat, but occasion-
ally split or join together. They pinch
and swell, and are usually between 10
and 70 cm-thick, and can plunge locally
as much as 3-4 m over a very short
distance.
Blocks of ore are laid out initially in
100 m x 80 m sections by driving 5 m-
wide tunnels, 2.2 m-high. Similar tun-
nels are then set off at approximately
90 degrees to create roughly 11 m by 11
m pillars, which are ultimately reduced
by slyping to 3 m by 3 m, providing an
extraction rate of 84%.
Blasted ore is loaded from the stopes
by a fleet of six low-profile Atlas Copco
Scooptram ST600LP loaders, tipping
into 1.8 m-diameter bored raises con-
necting to the main level boxes.
Rail haulage with trolley locomotives
is used to transport the ore to the shaft
on Level 3, and to the 900 t-capacity
main orepass on Level 2 that provides
storage for the 190 t/h jaw crusher lo-
cated at the 530 m-level.
Keeping a low profile at
Panasqueira
One hundred
years of history
Primary Metals Inc (PMI) is owner
of the Panasqueira mine in Por-
tugal, in production for over 100
years, and still the largest single
source of tungsten in the world.
Thin seams in low headroom make
the mining tricky, but Atlas Copco
Portugal was able to come up with
the perfect package of low head-
room mining equipment, including
its increasingly popular Scooptram
ST600LP underground loader. PMI
also chose Atlas Copco Finance
for funding the fleet purchase,
agreeing a simple supplier-credit
arrangement tailored to match
the demands of the operation.
As a result, overall mine produc-
tivity has increased by 25%, and
daily production records are
being broken. Above all, the part-
nership between equipment sup-
plier and end-user is proving to be
progressive and profitable!
Panasqueira mine is located at Barroca Grande in Portugal.

Crushed ore discharges onto the
1,203 m-long, 17% inclined Santa Bar-
bara conveyor belt that connects with a
3,000 t-capacity coarse ore bin located
beneath the mine office.
Primary mine ventilation is provided
naturally by several ventilation raises.
Airflow is controlled by curtains in main
areas and assisted by axial flow fans
where needed, particularly in the stopes.
Compressed air is needed for the
charging of the blast holes with ANFO,
and a new compressor unit was installed
underground in 2002.
The mine is supplied by 3.0 kV elec-
trical power, which is reduced to 380 V
for distribution to equipment.
Mining method
The stoping process begins when spiral
ramps are driven up to access the miner-
alized veins, and the orebody is opened
in four directions and blocked out.
East-west oriented tunnels are called
Drives, and those trending north-south
are called Panels. Drives and Panels are
driven 5 m-wide and, where they inter-
sect, 1.8 m-diameter raises are bored
between haulage levels to act as ore-
passes for all of the stopes. Chutes are
installed in the bottoms of the orepasses
to facilitate the loading of trains.
The height of the stopes is nominally
2.1 m, but can increase to 2.3 m in areas
where ore bearing veins are more vari-
able in their dip, strike or thickness.
Precise survey control is maintained,
so that all final pillars are aligned ver-
tically. Experience has shown that the
stopes will usually begin to collapse
about 4 or 5 months after extraction,
which gives plenty of time to glean any
remaining fines from the floor.
Stope drilling is carried out by new
generation Atlas Copco Rocket Boomer
S1L low profile electric hydraulic single
boom jumbos. Rounds are drilled 2.2
m-deep, utilizing a Vee-cut, and 41 and
43 mm-diameter drill bits. Drilling is
carried out on two shifts, with about
28 holes required per 5 m-wide round.
ANFO is loaded pneumatically into
Scooptram ST600LP under maintenance.
5 m 3 m 5 m 3 m11 m
Initial pillar Final pillars
Wolframite seam
Schematic of stope layout.

the blast holes, and electric delay deto-
nators along with small primers are
used for blasting. Blasting takes place
around midnight, and the mine then ven-
tilates throughout the night.
Each blasted face produces about
60-65 t of rock, and each rig can drill
up to 10 faces/shift, depending upon the
availability of working places.
After the blast, the muck pile is wa-
shed down, and the back is scaled. Ore
is loaded and hauled by the Scooptrams
from the headings to the orepasses.
Once the limits of the stopes are es-
tablished, then the final extraction takes
place with 3 m x 3 m pillars created
from the perimeter retreating to the
access ramp.
Drilling performance
The mine drill rig fleet comprises three
Atlas Copco Boomer H126 L drill rigs
mounted with COP 1238ME rock drills;
five Atlas Copco Rocket Boomer S1 L
low-profile drill rigs mounted with
COP 1838ME rock drills; and three
older drill rigs retrofitted with COP
1238LP rock drills.
All drilling uses ballistic button bits,
of which the preferred 43 mm-diameter
Atlas Copco Secoroc SR35 bits used by
the COP 1838 rock drills are returning
370 m/bit, while the 41 mm-diameter
bits are returning 450 m/bit. In such
abrasive rock, bit wear has to be closely
monitored to avoid an escalation in
costs. Likewise, regrinding has to be to
a high standard.
The recent addition of Rocket Boomer
S1 L models to the fleet has resulted in
a 50% increase in output/drill rig, while
less waste rock is generated due to the
lower profile required for safe operation.
This drill rig will operate in a seam
height as low as 1.3 m and is equipped
with four-wheel drive for maximum trac-
tability. The COP 1838 rock drill has
double reflex dampening for high-speed
Boomer S1 L drill rig in operation.
Core drilling in the levels.

drilling and excellent drill steel econ-
omy.
Drilling is performed primarily on
day and afternoon shifts on around 50
faces. These are maintained in close
proximity to one another, to avoid long
moves for the drill rigs.
Scooptram ST600LP
Each Scooptram ST600LP cleans 4-6
headings/shift on a maximum 200 m
round trip to tip, consuming 12 lit/h of
dieseline.
The ST600LP is an extremely robust
LHD designed specifically for demand-
ing low seam applications where the
back heights are as low as 1.6 m. It has
an operating weight of 17.3 t and a tram-
ming capacity of 6 t, equipped with a
3.1 cu m bucket. It is 8.625 m-long,
1.895 m-wide and 1.56 m from floor to
top of canopy. It is powered by a robust
6-cylinder diesel engine, providing a
mechanical breakout force of 8.7 t and
hydraulic breakout force of 9.3 t. For
visibility on the far side of the machine,
video cameras point forward and aft,
reporting to a screen in the driver’s cab.
The model has gained a well-deserved
reputation in the platinum, palladium
and chrome mines of South Africa,
where gradients are steep and rock is
highly abrasive. The ST600LP is now
proving itself in similar rigorous condi-
tions at Panasqueira, where the roof is
not well defined, and there are frequent
seam irregularities.
The mine currently operates at a rate
of 65,000 t/m with a recovered grade
of 0.2% WO3, which should produce
about 112 t of high grade and 20 t of
low-grade concentrate. Some 150 people
are employed underground on two shifts,
five days per week.
Acknowledgements
Atlas Copco is grateful to the directors
and management at Panasqueira for
their kind assistance in the production
of this article, and for providing access
to the mine statistics.
Scooptram ST600LP in low headroom stope.
Main access ramp to level 2 at Panasqueira mine.

www.atlascopco.com
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AtlasCopco2007
Second edition 2007
www.atlascopco.com
Printedmatterno.9851628901a
Mining Methods
in Underground Mining
MiningMethodsinUndergroundMining
www.atlascopco.com
This is optimised productivity
Good rock-drilling economy requires highly productive rock
drills. Atlas Copco’s superb COP 2238 paves the way for a
whole new cost scenario. World-leading technology, a unique
dual-damping system and 22 kW high-impact power ensures
performance and economy in a class of its own.
We call this optimised productivity.

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