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Longwall Mining

RAMANA M V, profile picture
RAMANA M V

Longwall mining is a major method of underground coal extraction worldwide. In India, coal accounts for over 50% of energy production, though most is still extracted via opencast mines. Longwall mining was introduced to India in the 1970s but has seen limited improvement and adoption since. Key longwall equipment includes powered roof supports, shearers, conveyors, and monitoring is important for strata control and safety. Organizing longwall panels and transferring equipment between panels is a complex operation involving dismantling, transport and reassembly of machinery.

Technology
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LONGWALL MINING Venkat
COAL - Background
COAL Most abundant fossil fuel Major fuel used for electricity generation world wide Safe and secure fossil fuel Cost effective
WORLD ELECTRICITY GENERATION (% By Fuel-2005) Consumption by India World Fuel (%) (%) Oil 32 37 Natural Gas 8 24 Coal 54 27 Nuclear Energy 1 6 Hydro-Electric 5 6 Total 100 100 (Source: BP Statistical Review of World Energy 2005)
WORLD SCENARIO As the International Energy Agency has commented: “World reserves of coal are enormous and compared with oil and natural gas, widely dispersed... The world’s proven reserve base represents about 200 years of production at current rates... Proven coal reserves have increased by over 50% in the past 22 years. The correlation of strong growth of proven coal reserves with robust production growth suggests that additions to proven coal reserves will continue to occur in those regions with strong, competitive coal industries.”
INDIAN SCENARIO Coal accounts for 63% of Country’s energy needs. Coal based thermal power generation capacity presently stands at 61,476MW and a capacity addition of around 60,000 MW has been targeted in next 7 years. Total annual hard coal production in India is about 373.79 million tonnes (2004-05) out of which nearly 80% is from Opencast Mines. SCCL share is 10%.
INDIAN SCENARIO Coal Demand & Production (in Million Tonnes) 2011-12 Demand 707 Production 550 Gap 157 (Source: Coal Summit 2005)
Proved coal reserves at end 2005
RESERVES - India As on January 2005 in Billion Tonnes TOTAL DEPTH(m) PROVED INDICATED INFERRED (In Bt) (%) 0-300 71 66.5 15 152.5 61.5 300-600 6.5 39.5 17 63 25 0-600 14.5 14 0.5 - 6 (Jharia) 600-1200 18 1.5 10.5 6 7.5 0-1200 93 117 38 248 100 (Source: GSI Report, January 2005)
RESERVES - SCCL As on January 2006 in Million Tonnes DEPTH PROVED INDICATED INFERRED TOTAL (m) 0-300 5505.49 2239.12 102.25 7846.86 300-600 2897.69 2900.71 553.05 6351.45 600-1200 0.00 1018.34 1928.95 2947.29 0-1200 8403.18 6158.17 2584.25 17145.60
LONGWALL – World & India
Longwall in India First mechanized powered support longwall caving face was introduced in August 1978 at Moonidih, CIL. First Longwall face introduced in GDK.7 Incline in September 1983 in SCCL. There is no much improvement taken place in India in respect of Longwall technology due to various reasons.
Longwall in India Reasons for less concentration on Longwalls in India Serious efforts not made perhaps due to availability of alternate technologies. Upgrading not made when most of the world improved in 90s. Spares management was poor. Coal India do not need due to opencast and flat gradients. Use of indigenous spares of low quality is increased, which deteriorated the condition of faces.
Australian Coal Industry World’s largest exporter of coal 230 mt worth Au$ 16 b (Rs. 53,000 crs) in 2004. Most of the 74 bt reserves in NSW and QLD 378 mt in 2004, 82 mt from underground. 24 longwalls produced 73 mt in 2004 and plans to produce 96 mt in 2006. 148 wagons per rake 2 km length, 8,500 t.
Australian Coal Industry Less than 25,000 employees. Each mine has 120 to 200 permanent and 100 contractors’ men. Productivity: OMY is 15,000 t. OMH 5t for UG, 10t for OC
Longwall Geometry - World Width Time Length (m) (m) 1970’s 150 1200 1980’s 225 1800 Today 330 3000
LONGWALL - METHOD
LONGWALL GENERAL LAYOUT TOP Gate FACE Dip direction Bottom Gate - Longwall mining method includes drivage of two long roadways in coal and joining them at the end by a perpendicular drivage forming a face.
Different Longwall Methods 1. Longwall Advancing 2. Longwall Retreating Method Method
Modern Longwall Plans in Australia
Modern Longwall Plans in Australia
Gateroad Plans in Australia
Advantages of Longwall Method High Recovery. Lower Operating Costs. Easier to Supervise. Easier to Train Miners. Works Under Weak Roof. Clean Coarse Product. Simple Ventilation.
Disadvantages of Longwall Method Small Problems = Big Production Losses. Dust Control Difficult. Overloading Conveyor System.
Retreat Longwall Mining Advantages Over Advance Longwall Mining Reserves are “Proven” on Development Gateroads in the “Solid” Gateroad Development is Separate Water Easier to Control Recovering Equipment Easier Easier Ventilation
Retreat Longwall Mining Disadvantages Over Advance Longwall Mining Delay in getting production for the preparation of first panel.
MAIN GATE WITH SWITCH TRAIN C H O C K S
LONGWALL METHOD Retreat per day –5 meters/day Production –3000 Tonnes/day Thickness of 2.0 m to 3.5 m
POWERED ROOF SUPPORT AT LONGWALL FACE
LONGWALL - EQUIPMENT
Equipment for Longwall Mining Powered Face Supports Shearer Armored Face Conveyor Conveyor System Electricals & Communication
CHOCK SHIELD SUPPORT
Powered Roof Supports (Two legged)
POWERED ROOF SUPPORT AT LONGWALL FACE Capacity -4x450 T to 4x800 T Thickness of -2.0 m to 3.5 m Weight -12 T to 20T Weight -1.5m
Powered Face Supports
Armored Face Conveyor
Armored Face Conveyor
Armored Face Conveyor
Armoured Face Conveyor (1 pan set)
Shearer working at Longwall Face
SHEARER WORKING AT LONGWALL FACE Capacity -2x375 Kw Thickness of 2.0 m to 4.5 m Web -0.63/0.85 Drum Dia -1.6 to 1.83m Length -10m
Shearer
Shearer - Front Half
Shearer - Rear Half
Shearer Drum
Cutter Bits with Spray
Conveyor Belts
LONGWALL – STRATA CONTROL
STRATA CONTROL PLAN OF A LONGWALL PANEL 1000 m 120 m Barrier Pillar Top Gate 50 L X C L C L X S RETREAT INDEX: GOAF C Convergence Station Longwall Panel dimensions L Load Cell 1000 m x 115 m X Extensometers S Stress cell FACE S S Bottom Gate 53 L X X C L C L 1000 m 200 m 120 m Barrier Pillar Not to scale
Strata monitoring of in a Longwall Panel • Gate Road ways studies. • Face monitoring. • Goaf monitoring.
Gate Road ways studies – Strata monitoring • Convergence indicators • Load cells • Tell tales • Stress capsules Cum.CONVERGENCE in Tail gate of a Longwall Panel 35 30 25 Cum.Convergence in mm 20 15 10 5 0 10.0m 30.0m 50.0m 70.0m 90.0m 110.0m 130.0m 150.0m 170.0m 190.0m 210.0m 230.0m 250.0m 270.0m 290.0m 310.0m 330.0m 350.0m 370.0m 390.0m 410.0m 430.0m LOCATION in mts
The maximum convergence depends on the following factors Caving properties of the strong bed causing weightings, indicated by the Caving Index Number ‘I’ of the strong bed. Thickness of cavable beds forming the immediate roof in between strong bed and the coal seam in terms of height of extraction. Resistance offered by the support system.
Convergence and Roof Degradation at Longwall Weightings (GDK.10A) Maximum Expected Roof Convergence Condition Upto 60 mm/m Convergence within permissible limit Above 60 upto 100 mm/m Minor roof fracturing increasing with the value of convergence Above 100 upto 160 mm/m Significant roof fracturing and roof degradation. Seriousness increasing with increase in convergence Above 160 mm/m Rock fall zone.
Face monitoring– Strata monitoring • Leg Pressures • Leg Closures • Face Convergence PRESSURE SURVEY Continuous Pressure Recorder in Mid Face of a Longwall Panel 40 Yield Pressure 35 30 PRESSURE (M pa) 25 Setting Pressure 20 15 33.6 39.3 56.2 74.1 95.4 111 119 141 163 180 198 220 237 259 279 305 324 345 369 386 412 FACE RETREAT in mts
Rated Support Resistance The Rated Support Resistance should take into account the following deficiencies during the actual operation. 1. Leakage in leg circuit 2. Setting load deficiencies 3. Miscellaneous (deviation from normal span, premature bleeding of leg circuits, etc.)
Goaf monitoring – Strata monitoring • Remote convergence indicator • Multi Point Borehole Extensometer (MPBEx) CAVING OF THE STRATA WITH RESPECT TO FACE PROGRESS sensors SURFACE SOIL-2.7m YellowSST 8m Light Brown Anc4 - 15m SST-7m 36m Hard Brown Anc3 -26m SST-17m 25m Anc2 -37.5m Grey & Brown 13.5m SST-12m Anc 1- 45m 6m Shaly Coal3m 68.0m 80.0m 141m Face progress Anchor1 Anchor2 Anchor3 Anchor4 Remarks
Longwall Caving Diagram Main Overburden Immediate Roof Hc F Dc T Cl Ro A Gob Shield Hs Coal Support Floor Hs = Seam Height Dc = Depth of Cut Ro = Rear Overhang Hc = Caving Height A = Caving Angle T = Canopy Tip to Face Cl = Canopy Length F = Forward Zone Sw = Shield Width (not shown)
Longwall Caving Cut after cut, shear after shear the AFC & subsequently Chock shield supports will be advanced and the immediate roof rock above caves in.
Main Fall - As the retreat further proceeds substantial area of main roof rock forms a plate & caves in by imposing load on supports, known as main weighting.
Periodic Fall
LONGWALL – ORGANISATION
Organisation Chart
MANPOWER Pre shift General Shift 1. EE/AE 1 1. Overman 1 2. Mech. Charge Hand 1 2. Mining Sirdar 1 3. Overman 1 3. Gate Road Support 6 4. Mining Sirdar 1 4. Face Supporting 5. Shearer F+3 (Bamboo bolting & 6. AFC & BSL F+5 Fore polling etc.) 8 7. Power pack & Chocks F+3 5. Face Cleaning 10 8. Switch train & 6. Slush Tanks cleaning U/Frame Shifting F+7 along M.G. 6 9. GBC F+4 7. Material transport 6 10. Miscellaneous 9 -------- ------------- 38 40
MANPOWER Production Shift 1. Under Manager 1 2. Engineer 1 3. Overman 1 4. Mining Sirdar 1 5. Shearer Operator 2 6. Multi Job Workmen 9 7. Face fitters 3 8. Face Electricians 1 9. Outbye belt Fitters 1 10. Outbye Electricians 1 11. Helpers 6 12. Conveyor Operators 6 13. Misc/cleaning 4 ------------- 37
LONGWALL – FACE TRANSFER
MESHING Wire meshing is laid in roof from 12 to 15m behind the face stop line with individual roof bolts for 5 to 8m and later on along with W- straps/Channel for balance portion at 1m interval. Maximum height will be extracted for the last 8m from face stop line, sothat enough clearance is there for PRS passing underneath the line supports. After stoppage of the face, meshing and bolting is done to the face also.
DISMANTLING All the equipment in the face are dismantled except chocks and loaded on to the GMT (Gyro Machine Trolley) and transported to surface of new face. Shearer is dismantled into two parts for easy transport. AFC pansets were dismantled in such a way that 5 pansets together forms a unit for loading onto GMT. Similarly BSL, Belt sections are dismantled and loaded on GMT.
CHOCKS TRANSPORT PRS turning is done generally from dip to raise and 2 buttress supports are used as goaf edge supports at dip most point of the face. PRS are being marched with self hydraulic power upto loading station and shifted on to GMT for further transport to surface or to new face.
SCCL – A Review
Strut Pit, Yellandu
Singareni • Presently operating 47 Underground and 11 Opencast mines. • Godavari Valley Coalfields spread out over 350 Kms.
L O C A T I O N
The Godavari Valley Coalfield L O C A T I O N
Mile stones - Technology 1975: Opencast mining 1979: Side Discharge Loaders 1981: Load Haul Dumpers and Road Headers 1983: Longwall mining 1986: Walking Dragline 1989: French Blasting Gallery method 1994: In-pit crushing and conveying 2004: Phasing out manual Coal filler launched.
Technology-Wise production- 2005-06 Opencast :23.42 mt (64.8%) Underground :12.71 mt (35.2%) Manual mining :7.12 mt Longwall :0.85 mt Intermediate mech. :4.74 mt (LHD, SDL, BG & RH)
PROJECTIONS TECH 2006-07 2011-12 2016-17 2021-22 PROD % PROD % PROD % PROD % (M.T) (M.T) (M.T) (M.T) HS 6.005 16 5.225 13 3.780 8 3.620 8 SDLS 3.30 9 2.865 7 1.610 4 1.280 3 LHD 1.655 4 1.110 3 1.12 2 0.680 1 LW 1.205 3 3.900 10 5.600 12 8.500 18 CM 0.400 1 1.800 4 1.770 4 2.000 4 BG 1.210 3 1.150 3 0.920 2 0.920 2 TOTAL UG 14.251 37 16.050 39 14.800 33 17.000 36 OC 21.749 63 24.750 61 30.200 67 30.500 64 TOTAL 37.500 100 40.800 100 45.000 100 47.500 100
General Organisation of SCCL C&MD SO Marketing Dir/ Fin. Dir/ P&P Dir/ Oprs. Dir/ PAW Dir/ E&M Finance Areas Areas Personnel E&M, UGM Int. Audit Forestry Civil Medical E&M, OC SO Safety R&D Estates PH&WS Co. Secy. CP&P Qual. Mgt IE Central WS Corp. Plg HRD Purchase Cap. budget Edn. Stores Proj. Plg. Vigilance Explrn. Security Survey IT Environ. Law
General Organisation of Areas GM SO Mines Safety IE Civil Finance IT Survey Medical HRD Purchase Qual.Mgt. Coal handling Personnel E&M Township Workshop WM Comn. Stores
General Organisation in the Mines Mine Manager Pit Office Safety Ventilation E&M Mntnce Min. Mntnce. Survey Welfare Production Shifts Drilling, Blasting Loading, Transport, Mine support, Coal handling etc.
Organisation of statutory personnel Owner Directors on the Board Corporate HoDs (Deemed Agents) General Manager (deemed Agents) Named Agent (group of mines) Mine Manager Officers For various disciplines Supervisors Competent persons
STATUS OF LONGWALLS AT SCCL
INTRODUCTION The first Longwall was commissioned in SCCL at GDK.7 Incline, RG-II in September, 1983. Till now 10 sets of Longwall were purchased by SCCL. Mainly the equipment was purchased from UK and China. Till now 70 Longwall panels have been completed in SCCL and presently 4 Longwall units are in operation in 4 Underground mines.
EXISTING LONGWALL MINES OF SCCL 2006-07 S Name of the mine No of No Units 1 PVK-5 Incline,KGM Area 1 unit 2 GDK-9 Incline,RG-II Area 1 unit 3 GDK-10A Incline,RG-II Area 1 unit 4 JK-5 Incline, YLD Area 1 unit
LONGWALL PRODUCTION TREND-SCCL 25 20 15 PROD (LT) 10 5 0 1983- 1984- 1985- 1986- 1987- 1988- 1989- 1990- 1991- 1992- 1993- 1994- 1995- 1996- 1997- 1998- 1999- 2000- 2001- 2002- 2003- 2004- 2005- 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 2000 01 02 03 04 05 06 LW PROD 1.33 2.47 5.75 6.18 6.12 6.12 4.62 6.32 12.17 13.2 16.1 10.4 20.19 22.9 19.3 16.42 15.79 13.66 11.27 10.1 11.17 11.19 8.5
INTRODUCTION OF LW SETS S Mine where LW sets No.of sets Support No introduced & Yr. capcities 1 GDK.7/9 Incline, RG-II 1, 1983 4 x 360T 2 VK-7 Incline, KGM 1, 1984 4 x 360T 3 GDK.11A Incline, RG-I 3, 1990-92 4x450T(2), 4x430T(1) 4 JK-5 Incline, YLD 1, 1990 4x450T 5 GDK.9Extention, RG-II 1, 1996 4x800T 6 GDK.10A Incline, RG-II 1, 1994 4x800T 7 Padmavathikhani, KGM 2, 1995-96 4x760T
GDK.7 INCLINE Longwall equipment introduced in no.3 seam bottom section in September 1983. After completion of two panels, due to non availability of the property the equipment was shifted to adjacent GDK.9 Incline. Main Problem - Strength of coal is high for Shearer cutting & sand stone bands running across the panel.
GDK.7 INCLINE Borehole Section showing 3 seam Top & Bot Section.
GDK.7 INCLINE Two panels have worked with 4x360T supports in No.3 seam bottom section with a face lengths of 110m and 96m. The production achieved is 0.8LT with an average production of 1900T/day.
VK.7 INCLINE Longwall equipment with 4x360T Conventional supports was introduced in Top seam in 1985. With 4x360T supports, 8 panels of 120m face length and 7 panels of 60m face length have been worked successfully. Second set (4x450T IFS) shifted from GDK.11A Inc in 1994 & is presently in operation. Experience in – varied face lengths, up hill transport, crossing the developed gallery, working in between goaves, fault running across the panel. Main Problems – Underrated capacity of supports, Cavity formation.
Depth Thickness Strata Description VK.7 INCLINE Borehole Section showing Top seam (Middle Section)
VK.7 INCLINE 8 panels of 120m face length have completed With 4x360T supports by producing around 3.6MT and daily production varied from 400 to 1800T. 7 panels of 60m face length have completed With 4x450T supports by producing around 1.6MT and daily production varied from 1000 to 1300T.
GDK.11A INCLINE Two longwall sets were introduced with 4x450T/4x430T supports during 1991, followed by 3rd Longwall unit with 4x450T supports during 1992. First time longwall was introduced in No.1 Seam of Ramagundam. Main Problems – Underrated capacity of supports, Oblique fault running across the panel, high water seepage, improper geo-technical investigations.
GDK.11A INCLINE Borehole Section showing No.1 seam (Bottom Section)
GDK.11A INCLINE Longwall unit –I : 2 panels worked producing around 0.5MT of coal. Longwall unit – II : 4 panels worked producing around 1.3MT of coal. Longwall unit – III : 3 panels worked producing around 0.96MT of coal. While working with Longwall unit-II & III, experienced more strata problems and cavity formations, due to underrated capacity of supports.
PADMAVATHIKHANI First time Chinese longwall was introduced in PVK in 1995 in Queen Seam (Top seam). 2 sets were introduced, One in 1995 and the other in 1996 with 4x760T supports. 11 panels have been completed by producing around 5 MT. Experience in – varied face lengths, negotiation of fault, deviation of gate roadways. Main Problems – Non-availability of Spares.
PADMAVATHIKHANI Borehole Section showing Top seam (Middle Section)
JK-5 INCLINE Longwall with 4x450T supports (IFS) was commissioned in June 1990. Longwall panels were extracted in both, Top and bottom sections of Queen (Top) seam after allowing for goaf settlement. 2 panels in Queen seam bottom section and 8 panels in Queen seam Top section have been completed by producing around 2.7MT of coal. Experience in – varied face lengths, negotiation of fault, in between goaves, steep gradient (1 in 3.6). Main Problems – Geological disturbances, Cavity formation, underrated capacity of supports.
JK-5 INCLINE Borehole Section showing Top seam Top & Bottom section
GDK.9/9E INCLINE Longwall equipment (4x360T) introduced in no.3 seam bottom section in 1986 which was shifted from GDK.7 Incline. New Longwall set with 4x800T capacity was introduced in No.1 seam in 1996. Main Problem – underrated capacity of supports for 3 seam, Cavity formation, Insufficient geological data, slow progress in development of panels, more water seepage, spares mgmt.
GDK.9/9E INCLINE Borehole Section showing 1 seam
GDK.10A INCLINE Longwall equipment (4x800T IFS) was introduced in no.1 seam in 1994. GDK.10A longwall produced daily, weekly and monthly record output in India. In the year 1997-98, the mine produced 8.67LT. GDK 10A produced 5.40 LT of coal against the target of 5.38 LT in the year 2005-06. Main Problem –more water seepage, non-availability of good quality spares, Cavity formation.
GDK.10A INCLINE Borehole Section showing 1 seam
FUTURE LONGWALLS AT SCCL
FUTURE LONGWALL PROJECTS • Adriyala Shaft Project – Extension of GDK.10A dip side • Jallaram Shaft Project – Extension of GDK.9 Inc Dip side • Peddampet Shaft Project - Extension of GDK.11A Inc Dip side • Kakatiya Longwall Project, Bhupalpally - Steeply inclined, New mine. • Shanthikhani Longwall Project, Bellampalli - Extenstion of existing mine
STATUS OF APPROVAL OF LW PROJECTS S. Project FR Status of EMP Status of GOI approval No approved by SCCL Board 1 Adriyala July’ 2003 EC obtained Sanctioned from GoI in Sept 06 11.10.2004 2 Shanthikhani Dec’ 2003 EC obtained Submitted to GOI on 26.02.04. 24.01.2006 In principle approval received. PIB note submitted on 01.01.05 3 KTK LW June’ 2005 EMP to be prepared Submitted to GOI 5.08.2005 4 Jallaram Oct’ 2004 Public hearing completed. Submitted to GOI 11.11.04 Application for EC under preparation. 5 Peddampeta Dec’ 2003 Public hearing completed. Submitted to GOI 26.02.04 Application for EC under preparation
ADRIYALA SHAFT PROJECT 1. Location : Ramagundam coal belt Ramagundam Area 2. Geological Block : RG SB-II & RG SB-III 3. Geological Reserves : 109.59 Mt 4. Extractable Reserves (Apr.) : 43.38 Mt 5. Area (in Sq.Km) : 3.40 6. Capacity (MTPA) : 2.14 7. Life of the Mine : 31 years 8. Face length : 150m 9. Panel length : 700 - 1300 m 10. Depth range : 294 – 644m 11. Gradient : 1 in 6.0 to 1 in 7.8 :
ADRIYALA SHAFT PROJECT Details of seams: Seam Avg. Height of Geological Extractable Grade Thickness Extraction Reserves Reserves (m) (m) (Mt) (MT) I 5.64 3.5 27.99 10.98 E II 3.27 2.0 15.24 6.07 D III 9.40 3.5(Top)/ 43.09 23.31 D 3.5(Bot) IV 3.66 3.5 15.56 11.28 C
SHANTIKHANI LONGWALL PROJECT 1. Location : Dorli - Bellampalli coal belt Bellampalli Area 2. Geological Block : Shantikhani Extn Block 3. Geological Reserves : 8.87 Mt 4. Extractable Reserves (Apr.) : 17.78 Mt 5. Area (in Sq. Km) : 6.81 6. Capacity (MTPA) : 1.17 7. Life of the Mine : 23 Years 8. Face length : 150m 9. Panel length : 450 - 2000 m 10. Depth range : 309 – 596m 11. Gradient : 1 in 3.5 to 1 in 5
SHANTIKHANI LONGWALL PROJECT Details of seams (Phase-I) Seam Avg. Height of Geological Extractable Grade Thickness Extraction Reserves (Mt) Reserves (m) (m) (Mt) SJ Top 1.88 1.5 18.96 3.91 F SJ Bot 3.18 2.5, 3.5 29.91 13.87 D
KAKATIYA LONGWALL PROJECT 1. Location : Mulug coal belt Bhoopalpalli Area 2. Geological Block : Gollapalli block & Peddapur block 3. Geological Reserves : 67.45 Mt (Phase-I)+ 60.06 Mt (Phase-II) 4. Extractable Reserves (Apr.) : 40.02 Mt (Phase-I)+ 35.99 Mt (Phase-II) 5. Area (in Sq. Km) : 9.71 6. Capacity (MTPA) : 2.16 7. Life of the Mine : 24 + 22 Years 8. Face length : 250m 9. Panel length : 1200 - 2900 m 10. Depth range : 35 – 412m 11. Gradient : 1 in 2.8 to 1 in 3.3
KAKATIYA LONGWALL PROJECT Details of seams (Phase-I) Seam Avg. Height of Geological Extractable Grade Thickness Extraction Reserves Reserves (Mt) (m) (m) (Mt) IA 2.02 2.0 12.16 7.62 E I 2.66 2.5 17.18 9.45 F II 2.72 2.5 17.55 9.71 F III 3.05 3.0 20.53 13.24 B
JALLARAM SHAFT PROJECT 1. Location : Ramagundam coal belt Ramagundam Area 2. Geological Block : RG SB-II 3. Geological Reserves : 206 Mt 4. Extractable Reserves (Apr.) : 79 Mt 5. Area (in Sq.Km) : 7.29 6. Capacity (MTPA) : 2.28 7. Life of the Mine : 53 years 8. Face length : 200m 9. Panel length : 500 - 1800 m 10. Depth range : 123 – 579m 11. Gradient : 1 in 5 to 1 in 8
JALLARAM SHAFT PROJECT Details of seams Seam Avg. Height of Geological Extractable Grade Thickness Extraction Reserves Reserves (m) (m) (Mt) (Mt) I 5.09 3.0 53.99 14.13 E II 2.99 2.0 27.43 12.17 E III 8.79 3.0 (Top)/ 85.04 36.91 D 3.5 (Bot) IV 3.00 3.0 29.19 16.21 B
PEDDAMPETA SHAFT PROJECT 1. Location : Ramagundam coal belt Ramagundam Area 2. Geological Block : GDK-6B Integrated Mine Block 3. Geological Reserves : 112.62 Mt 4. Extractable Reserves (Apr.) : 41.40 Mt 5. Area (in Sq.Km) : 7.25 6. Capacity (MTPA) : 1.46 7. Life of the Mine : 32 Years 8. Face length : 150m 9. Panel length : 470 - 1200 m 10. Depth range : 118 – 443m 11. Gradient : 1 in 6 to 1 in 10
PEDDAMPETA SHAFT PROJECT Details of seams Seam Avg. Height of Geological Extractable Grade Thickness Extraction Reserves (Mt) Reserves (m) (m) (Mt) II 2.64 2.0 24.27 7.06 E III 8.69 2.0 (Top)/ 65.69 21.39 D 3.5 (Bot) IV 2.50 2.5 22.66 12.95 B
Variants of Longwall Mining (NEW CONCEPTS)
Punch Longwall - Developing longwall panels directly off high walls of OC
Punch Longwall Field site operations
Punch Longwall Advantages Step change in cost and productivity More production capacity High productivity & low cost Longer term and higher % of reserves extraction Easy logistics – near surface High gate road development rates feasible Higher and faster returns on investment Total investment ~ $100 million – compared with > $300 millions UG
Longwall Top Coal Caving (LTCC) Technical Principle Of Top Caving Rock stress 1st pressure Low stress Stress 2nd pressure Compact peak abrupt drop peak stress Pressure curve of top coalseam Fracture Virgin 5600 Coal Broken Coal coal goaf caving 2800 Working Height Front AFC Rear AFC back
Longwall Top Coal Caving (LTCC) Supports used
Longwall Top Coal Caving (LTCC) Advantages of LTCC • Increased resource recovery in thick seams (> 75%) • Lower face working height (better face control) • Improved spontaneous combustion control • More efficient capital utilisation/ financial performance • Reduced operating costs • Improved production consistency • Less gate road development requirements • Some dust and gas issues
LONGWALL – INDIAN PERFORMANCE
INDIAN LONGWALL - PAST EXPERIENCE: - Introduction of advanced technology system in Indian coal mining industry marked a major step with the installation of first mechanized Longwall Powered support face at Moonidih in August 1978. - In between 1978 to 1985, a major number of first generation Longwall faces started through out India in various mines of CIL such as Moonidih, Jhanjra, Seetalpur, Dhemomain and Pathakhera Colliery and in SCCL at GDK- 7 & VK-7 Incline.
INDIAN LONGWALL - PAST EXPERIENCE: - Churcha Longwall face failed due to dynamic loading. - Jhanjra with shallow depth Longwall working face ran into acute spares problem. - Kottadih face failed after successful completion of two Longwall panels due to dynamic loading and underrated capacity of supports. - GDK.11A failed due to underrated capacity of supports.
LONGWALL- SCCL - PAST EXPERIENCE: Longwall technology was introduced in Seven mines of SCCL. Their performance has been: • GDK-10A, JK-5 and VK-7 Incline gave consistently good results, and • The other four mines GDK-7, GDK-9, GDK- 11A and PVK suffered mainly due to non availability of sufficient geological data.
INDIAN LONGWALL MAIN REASON : Insufficient geo-technical investigations resulted in surprises by encountering major geological disturbances while working the longwalls. Thus effecting the performance of Longwalls to the maximum extent.
INDIAN LONGWALL - PRESENT & FUTURE : - With the likely reduction of contribution from Open cast and the more or less stagnant production from Underground by Conventional methods, it is time that an impetus is given to boost Long wall Technology to able to meet the future energy needs of the country. - On the positive side, coal companies have now gained sufficient experiences right from senior executive level to front line workforce to be able to plan, execute and work longwall faces. What are required are proper geo-technical investigations for effective layout of longwall panels.
REASONS FOR POOR PERFORMANCE OF LONGWALL >Large expansion in opencast mining in the past two decades provided cheaper and safe method for bulk coal production and as a result long wall had to take back seat. >Clear strategies were not pursued for its sustenance as there was mixed results from long wall in the early years of its introduction.
REASONS FOR POOR PERFORMANCE OF LONGWALL >Long walls were introduced mostly in the blocks left over by working Bord and pillar method. Clean and extensive blocks have not been identified. Even the smaller blocks, which were identified, were of inferior grade coal. >Long wall had to co exist with the conventional mining in most of the mines, which caused management problems. >There were some deficiencies in the imported spares management and the supplies were not reaching in time.
REASONS FOR POOR PERFORMANCE OF LONGWALL >Coal companies were sensitive to the failures of a few long wall faces and were not prepared to risk huge investments. >Development could not keep pace with the extraction of Long wall panels, slow progress in dip has delayed the formation of Long wall panels and affected the performance.
FUTURE REQUIREMENTS - Longwall should be promoted as a technology mission. - A high level thrust group could be constitute at national level to promote, coordinate and interact different aspects related to Longwall technology.
FUTURE REQUIREMENTS - Huge investments incurred on different operations for extraction of coal from greater depths in future can be attained by imposing a special cess on present OC production or from other sources. - R&D efforts are to be doubled. - Efforts are required by the policy makers to transform ideas into actions.
FUTURE REQUIREMENTS - Foreign participation is required for extraction of thin seams and steeply inclined seams. - The manufacturing companies of India such as MAMC and Jessop are to be reconstructed/ re-organized. - More number of longwall blocks are to be identified to assure the market for manufacturers.
THANK YOU

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Longwall Mining

  • 3. COAL Most abundant fossil fuel Major fuel used for electricity generation world wide Safe and secure fossil fuel Cost effective
  • 4. WORLD ELECTRICITY GENERATION (% By Fuel-2005) Consumption by India World Fuel (%) (%) Oil 32 37 Natural Gas 8 24 Coal 54 27 Nuclear Energy 1 6 Hydro-Electric 5 6 Total 100 100 (Source: BP Statistical Review of World Energy 2005)
  • 5. WORLD SCENARIO As the International Energy Agency has commented: “World reserves of coal are enormous and compared with oil and natural gas, widely dispersed... The world’s proven reserve base represents about 200 years of production at current rates... Proven coal reserves have increased by over 50% in the past 22 years. The correlation of strong growth of proven coal reserves with robust production growth suggests that additions to proven coal reserves will continue to occur in those regions with strong, competitive coal industries.”
  • 6. INDIAN SCENARIO Coal accounts for 63% of Country’s energy needs. Coal based thermal power generation capacity presently stands at 61,476MW and a capacity addition of around 60,000 MW has been targeted in next 7 years. Total annual hard coal production in India is about 373.79 million tonnes (2004-05) out of which nearly 80% is from Opencast Mines. SCCL share is 10%.
  • 7. INDIAN SCENARIO Coal Demand & Production (in Million Tonnes) 2011-12 Demand 707 Production 550 Gap 157 (Source: Coal Summit 2005)
  • 8. Proved coal reserves at end 2005
  • 9. RESERVES - India As on January 2005 in Billion Tonnes TOTAL DEPTH(m) PROVED INDICATED INFERRED (In Bt) (%) 0-300 71 66.5 15 152.5 61.5 300-600 6.5 39.5 17 63 25 0-600 14.5 14 0.5 - 6 (Jharia) 600-1200 18 1.5 10.5 6 7.5 0-1200 93 117 38 248 100 (Source: GSI Report, January 2005)
  • 10. RESERVES - SCCL As on January 2006 in Million Tonnes DEPTH PROVED INDICATED INFERRED TOTAL (m) 0-300 5505.49 2239.12 102.25 7846.86 300-600 2897.69 2900.71 553.05 6351.45 600-1200 0.00 1018.34 1928.95 2947.29 0-1200 8403.18 6158.17 2584.25 17145.60
  • 12. Longwall in India First mechanized powered support longwall caving face was introduced in August 1978 at Moonidih, CIL. First Longwall face introduced in GDK.7 Incline in September 1983 in SCCL. There is no much improvement taken place in India in respect of Longwall technology due to various reasons.
  • 13. Longwall in India Reasons for less concentration on Longwalls in India Serious efforts not made perhaps due to availability of alternate technologies. Upgrading not made when most of the world improved in 90s. Spares management was poor. Coal India do not need due to opencast and flat gradients. Use of indigenous spares of low quality is increased, which deteriorated the condition of faces.
  • 14. Australian Coal Industry World’s largest exporter of coal 230 mt worth Au$ 16 b (Rs. 53,000 crs) in 2004. Most of the 74 bt reserves in NSW and QLD 378 mt in 2004, 82 mt from underground. 24 longwalls produced 73 mt in 2004 and plans to produce 96 mt in 2006. 148 wagons per rake 2 km length, 8,500 t.
  • 15. Australian Coal Industry Less than 25,000 employees. Each mine has 120 to 200 permanent and 100 contractors’ men. Productivity: OMY is 15,000 t. OMH 5t for UG, 10t for OC
  • 16. Longwall Geometry - World Width Time Length (m) (m) 1970’s 150 1200 1980’s 225 1800 Today 330 3000
  • 17. LONGWALL - METHOD
  • 18. LONGWALL GENERAL LAYOUT TOP Gate FACE Dip direction Bottom Gate - Longwall mining method includes drivage of two long roadways in coal and joining them at the end by a perpendicular drivage forming a face.
  • 19. Different Longwall Methods 1. Longwall Advancing 2. Longwall Retreating Method Method
  • 20. Modern Longwall Plans in Australia
  • 22. Gateroad Plans in Australia
  • 23. Advantages of Longwall Method High Recovery. Lower Operating Costs. Easier to Supervise. Easier to Train Miners. Works Under Weak Roof. Clean Coarse Product. Simple Ventilation.
  • 24. Disadvantages of Longwall Method Small Problems = Big Production Losses. Dust Control Difficult. Overloading Conveyor System.
  • 25. Retreat Longwall Mining Advantages Over Advance Longwall Mining Reserves are “Proven” on Development Gateroads in the “Solid” Gateroad Development is Separate Water Easier to Control Recovering Equipment Easier Easier Ventilation
  • 26. Retreat Longwall Mining Disadvantages Over Advance Longwall Mining Delay in getting production for the preparation of first panel.
  • 27. MAIN GATE WITH SWITCH TRAIN C H O C K S
  • 28. LONGWALL METHOD Retreat per day –5 meters/day Production –3000 Tonnes/day Thickness of 2.0 m to 3.5 m
  • 29. POWERED ROOF SUPPORT AT LONGWALL FACE
  • 31. Equipment for Longwall Mining Powered Face Supports Shearer Armored Face Conveyor Conveyor System Electricals & Communication
  • 33. Powered Roof Supports (Two legged)
  • 34. POWERED ROOF SUPPORT AT LONGWALL FACE Capacity -4x450 T to 4x800 T Thickness of -2.0 m to 3.5 m Weight -12 T to 20T Weight -1.5m
  • 39. Armoured Face Conveyor (1 pan set)
  • 40. Shearer working at Longwall Face
  • 41. SHEARER WORKING AT LONGWALL FACE Capacity -2x375 Kw Thickness of 2.0 m to 4.5 m Web -0.63/0.85 Drum Dia -1.6 to 1.83m Length -10m
  • 49. STRATA CONTROL PLAN OF A LONGWALL PANEL 1000 m 120 m Barrier Pillar Top Gate 50 L X C L C L X S RETREAT INDEX: GOAF C Convergence Station Longwall Panel dimensions L Load Cell 1000 m x 115 m X Extensometers S Stress cell FACE S S Bottom Gate 53 L X X C L C L 1000 m 200 m 120 m Barrier Pillar Not to scale
  • 50. Strata monitoring of in a Longwall Panel • Gate Road ways studies. • Face monitoring. • Goaf monitoring.
  • 51. Gate Road ways studies – Strata monitoring • Convergence indicators • Load cells • Tell tales • Stress capsules Cum.CONVERGENCE in Tail gate of a Longwall Panel 35 30 25 Cum.Convergence in mm 20 15 10 5 0 10.0m 30.0m 50.0m 70.0m 90.0m 110.0m 130.0m 150.0m 170.0m 190.0m 210.0m 230.0m 250.0m 270.0m 290.0m 310.0m 330.0m 350.0m 370.0m 390.0m 410.0m 430.0m LOCATION in mts
  • 52. The maximum convergence depends on the following factors Caving properties of the strong bed causing weightings, indicated by the Caving Index Number ‘I’ of the strong bed. Thickness of cavable beds forming the immediate roof in between strong bed and the coal seam in terms of height of extraction. Resistance offered by the support system.
  • 53. Convergence and Roof Degradation at Longwall Weightings (GDK.10A) Maximum Expected Roof Convergence Condition Upto 60 mm/m Convergence within permissible limit Above 60 upto 100 mm/m Minor roof fracturing increasing with the value of convergence Above 100 upto 160 mm/m Significant roof fracturing and roof degradation. Seriousness increasing with increase in convergence Above 160 mm/m Rock fall zone.
  • 54. Face monitoring– Strata monitoring • Leg Pressures • Leg Closures • Face Convergence PRESSURE SURVEY Continuous Pressure Recorder in Mid Face of a Longwall Panel 40 Yield Pressure 35 30 PRESSURE (M pa) 25 Setting Pressure 20 15 33.6 39.3 56.2 74.1 95.4 111 119 141 163 180 198 220 237 259 279 305 324 345 369 386 412 FACE RETREAT in mts
  • 55. Rated Support Resistance The Rated Support Resistance should take into account the following deficiencies during the actual operation. 1. Leakage in leg circuit 2. Setting load deficiencies 3. Miscellaneous (deviation from normal span, premature bleeding of leg circuits, etc.)
  • 56. Goaf monitoring – Strata monitoring • Remote convergence indicator • Multi Point Borehole Extensometer (MPBEx) CAVING OF THE STRATA WITH RESPECT TO FACE PROGRESS sensors SURFACE SOIL-2.7m YellowSST 8m Light Brown Anc4 - 15m SST-7m 36m Hard Brown Anc3 -26m SST-17m 25m Anc2 -37.5m Grey & Brown 13.5m SST-12m Anc 1- 45m 6m Shaly Coal3m 68.0m 80.0m 141m Face progress Anchor1 Anchor2 Anchor3 Anchor4 Remarks
  • 57. Longwall Caving Diagram Main Overburden Immediate Roof Hc F Dc T Cl Ro A Gob Shield Hs Coal Support Floor Hs = Seam Height Dc = Depth of Cut Ro = Rear Overhang Hc = Caving Height A = Caving Angle T = Canopy Tip to Face Cl = Canopy Length F = Forward Zone Sw = Shield Width (not shown)
  • 58. Longwall Caving Cut after cut, shear after shear the AFC & subsequently Chock shield supports will be advanced and the immediate roof rock above caves in.
  • 59. Main Fall - As the retreat further proceeds substantial area of main roof rock forms a plate & caves in by imposing load on supports, known as main weighting.
  • 63. MANPOWER Pre shift General Shift 1. EE/AE 1 1. Overman 1 2. Mech. Charge Hand 1 2. Mining Sirdar 1 3. Overman 1 3. Gate Road Support 6 4. Mining Sirdar 1 4. Face Supporting 5. Shearer F+3 (Bamboo bolting & 6. AFC & BSL F+5 Fore polling etc.) 8 7. Power pack & Chocks F+3 5. Face Cleaning 10 8. Switch train & 6. Slush Tanks cleaning U/Frame Shifting F+7 along M.G. 6 9. GBC F+4 7. Material transport 6 10. Miscellaneous 9 -------- ------------- 38 40
  • 64. MANPOWER Production Shift 1. Under Manager 1 2. Engineer 1 3. Overman 1 4. Mining Sirdar 1 5. Shearer Operator 2 6. Multi Job Workmen 9 7. Face fitters 3 8. Face Electricians 1 9. Outbye belt Fitters 1 10. Outbye Electricians 1 11. Helpers 6 12. Conveyor Operators 6 13. Misc/cleaning 4 ------------- 37
  • 66. MESHING Wire meshing is laid in roof from 12 to 15m behind the face stop line with individual roof bolts for 5 to 8m and later on along with W- straps/Channel for balance portion at 1m interval. Maximum height will be extracted for the last 8m from face stop line, sothat enough clearance is there for PRS passing underneath the line supports. After stoppage of the face, meshing and bolting is done to the face also.
  • 67. DISMANTLING All the equipment in the face are dismantled except chocks and loaded on to the GMT (Gyro Machine Trolley) and transported to surface of new face. Shearer is dismantled into two parts for easy transport. AFC pansets were dismantled in such a way that 5 pansets together forms a unit for loading onto GMT. Similarly BSL, Belt sections are dismantled and loaded on GMT.
  • 68. CHOCKS TRANSPORT PRS turning is done generally from dip to raise and 2 buttress supports are used as goaf edge supports at dip most point of the face. PRS are being marched with self hydraulic power upto loading station and shifted on to GMT for further transport to surface or to new face.
  • 69. SCCL – A Review
  • 71. Singareni • Presently operating 47 Underground and 11 Opencast mines. • Godavari Valley Coalfields spread out over 350 Kms.
  • 73. The Godavari Valley Coalfield L O C A T I O N
  • 74. Mile stones - Technology 1975: Opencast mining 1979: Side Discharge Loaders 1981: Load Haul Dumpers and Road Headers 1983: Longwall mining 1986: Walking Dragline 1989: French Blasting Gallery method 1994: In-pit crushing and conveying 2004: Phasing out manual Coal filler launched.
  • 75. Technology-Wise production- 2005-06 Opencast :23.42 mt (64.8%) Underground :12.71 mt (35.2%) Manual mining :7.12 mt Longwall :0.85 mt Intermediate mech. :4.74 mt (LHD, SDL, BG & RH)
  • 76. PROJECTIONS TECH 2006-07 2011-12 2016-17 2021-22 PROD % PROD % PROD % PROD % (M.T) (M.T) (M.T) (M.T) HS 6.005 16 5.225 13 3.780 8 3.620 8 SDLS 3.30 9 2.865 7 1.610 4 1.280 3 LHD 1.655 4 1.110 3 1.12 2 0.680 1 LW 1.205 3 3.900 10 5.600 12 8.500 18 CM 0.400 1 1.800 4 1.770 4 2.000 4 BG 1.210 3 1.150 3 0.920 2 0.920 2 TOTAL UG 14.251 37 16.050 39 14.800 33 17.000 36 OC 21.749 63 24.750 61 30.200 67 30.500 64 TOTAL 37.500 100 40.800 100 45.000 100 47.500 100
  • 77. General Organisation of SCCL C&MD SO Marketing Dir/ Fin. Dir/ P&P Dir/ Oprs. Dir/ PAW Dir/ E&M Finance Areas Areas Personnel E&M, UGM Int. Audit Forestry Civil Medical E&M, OC SO Safety R&D Estates PH&WS Co. Secy. CP&P Qual. Mgt IE Central WS Corp. Plg HRD Purchase Cap. budget Edn. Stores Proj. Plg. Vigilance Explrn. Security Survey IT Environ. Law
  • 78. General Organisation of Areas GM SO Mines Safety IE Civil Finance IT Survey Medical HRD Purchase Qual.Mgt. Coal handling Personnel E&M Township Workshop WM Comn. Stores
  • 79. General Organisation in the Mines Mine Manager Pit Office Safety Ventilation E&M Mntnce Min. Mntnce. Survey Welfare Production Shifts Drilling, Blasting Loading, Transport, Mine support, Coal handling etc.
  • 80. Organisation of statutory personnel Owner Directors on the Board Corporate HoDs (Deemed Agents) General Manager (deemed Agents) Named Agent (group of mines) Mine Manager Officers For various disciplines Supervisors Competent persons
  • 82. INTRODUCTION The first Longwall was commissioned in SCCL at GDK.7 Incline, RG-II in September, 1983. Till now 10 sets of Longwall were purchased by SCCL. Mainly the equipment was purchased from UK and China. Till now 70 Longwall panels have been completed in SCCL and presently 4 Longwall units are in operation in 4 Underground mines.
  • 83. EXISTING LONGWALL MINES OF SCCL 2006-07 S Name of the mine No of No Units 1 PVK-5 Incline,KGM Area 1 unit 2 GDK-9 Incline,RG-II Area 1 unit 3 GDK-10A Incline,RG-II Area 1 unit 4 JK-5 Incline, YLD Area 1 unit
  • 84. LONGWALL PRODUCTION TREND-SCCL 25 20 15 PROD (LT) 10 5 0 1983- 1984- 1985- 1986- 1987- 1988- 1989- 1990- 1991- 1992- 1993- 1994- 1995- 1996- 1997- 1998- 1999- 2000- 2001- 2002- 2003- 2004- 2005- 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 2000 01 02 03 04 05 06 LW PROD 1.33 2.47 5.75 6.18 6.12 6.12 4.62 6.32 12.17 13.2 16.1 10.4 20.19 22.9 19.3 16.42 15.79 13.66 11.27 10.1 11.17 11.19 8.5
  • 85. INTRODUCTION OF LW SETS S Mine where LW sets No.of sets Support No introduced & Yr. capcities 1 GDK.7/9 Incline, RG-II 1, 1983 4 x 360T 2 VK-7 Incline, KGM 1, 1984 4 x 360T 3 GDK.11A Incline, RG-I 3, 1990-92 4x450T(2), 4x430T(1) 4 JK-5 Incline, YLD 1, 1990 4x450T 5 GDK.9Extention, RG-II 1, 1996 4x800T 6 GDK.10A Incline, RG-II 1, 1994 4x800T 7 Padmavathikhani, KGM 2, 1995-96 4x760T
  • 86. GDK.7 INCLINE Longwall equipment introduced in no.3 seam bottom section in September 1983. After completion of two panels, due to non availability of the property the equipment was shifted to adjacent GDK.9 Incline. Main Problem - Strength of coal is high for Shearer cutting & sand stone bands running across the panel.
  • 87. GDK.7 INCLINE Borehole Section showing 3 seam Top & Bot Section.
  • 88. GDK.7 INCLINE Two panels have worked with 4x360T supports in No.3 seam bottom section with a face lengths of 110m and 96m. The production achieved is 0.8LT with an average production of 1900T/day.
  • 89. VK.7 INCLINE Longwall equipment with 4x360T Conventional supports was introduced in Top seam in 1985. With 4x360T supports, 8 panels of 120m face length and 7 panels of 60m face length have been worked successfully. Second set (4x450T IFS) shifted from GDK.11A Inc in 1994 & is presently in operation. Experience in – varied face lengths, up hill transport, crossing the developed gallery, working in between goaves, fault running across the panel. Main Problems – Underrated capacity of supports, Cavity formation.
  • 90. Depth Thickness Strata Description VK.7 INCLINE Borehole Section showing Top seam (Middle Section)
  • 91. VK.7 INCLINE 8 panels of 120m face length have completed With 4x360T supports by producing around 3.6MT and daily production varied from 400 to 1800T. 7 panels of 60m face length have completed With 4x450T supports by producing around 1.6MT and daily production varied from 1000 to 1300T.
  • 92. GDK.11A INCLINE Two longwall sets were introduced with 4x450T/4x430T supports during 1991, followed by 3rd Longwall unit with 4x450T supports during 1992. First time longwall was introduced in No.1 Seam of Ramagundam. Main Problems – Underrated capacity of supports, Oblique fault running across the panel, high water seepage, improper geo-technical investigations.
  • 93. GDK.11A INCLINE Borehole Section showing No.1 seam (Bottom Section)
  • 94. GDK.11A INCLINE Longwall unit –I : 2 panels worked producing around 0.5MT of coal. Longwall unit – II : 4 panels worked producing around 1.3MT of coal. Longwall unit – III : 3 panels worked producing around 0.96MT of coal. While working with Longwall unit-II & III, experienced more strata problems and cavity formations, due to underrated capacity of supports.
  • 95. PADMAVATHIKHANI First time Chinese longwall was introduced in PVK in 1995 in Queen Seam (Top seam). 2 sets were introduced, One in 1995 and the other in 1996 with 4x760T supports. 11 panels have been completed by producing around 5 MT. Experience in – varied face lengths, negotiation of fault, deviation of gate roadways. Main Problems – Non-availability of Spares.
  • 96. PADMAVATHIKHANI Borehole Section showing Top seam (Middle Section)
  • 97. JK-5 INCLINE Longwall with 4x450T supports (IFS) was commissioned in June 1990. Longwall panels were extracted in both, Top and bottom sections of Queen (Top) seam after allowing for goaf settlement. 2 panels in Queen seam bottom section and 8 panels in Queen seam Top section have been completed by producing around 2.7MT of coal. Experience in – varied face lengths, negotiation of fault, in between goaves, steep gradient (1 in 3.6). Main Problems – Geological disturbances, Cavity formation, underrated capacity of supports.
  • 98. JK-5 INCLINE Borehole Section showing Top seam Top & Bottom section
  • 99. GDK.9/9E INCLINE Longwall equipment (4x360T) introduced in no.3 seam bottom section in 1986 which was shifted from GDK.7 Incline. New Longwall set with 4x800T capacity was introduced in No.1 seam in 1996. Main Problem – underrated capacity of supports for 3 seam, Cavity formation, Insufficient geological data, slow progress in development of panels, more water seepage, spares mgmt.
  • 100. GDK.9/9E INCLINE Borehole Section showing 1 seam
  • 101. GDK.10A INCLINE Longwall equipment (4x800T IFS) was introduced in no.1 seam in 1994. GDK.10A longwall produced daily, weekly and monthly record output in India. In the year 1997-98, the mine produced 8.67LT. GDK 10A produced 5.40 LT of coal against the target of 5.38 LT in the year 2005-06. Main Problem –more water seepage, non-availability of good quality spares, Cavity formation.
  • 102. GDK.10A INCLINE Borehole Section showing 1 seam
  • 104. FUTURE LONGWALL PROJECTS • Adriyala Shaft Project – Extension of GDK.10A dip side • Jallaram Shaft Project – Extension of GDK.9 Inc Dip side • Peddampet Shaft Project - Extension of GDK.11A Inc Dip side • Kakatiya Longwall Project, Bhupalpally - Steeply inclined, New mine. • Shanthikhani Longwall Project, Bellampalli - Extenstion of existing mine
  • 105. STATUS OF APPROVAL OF LW PROJECTS S. Project FR Status of EMP Status of GOI approval No approved by SCCL Board 1 Adriyala July’ 2003 EC obtained Sanctioned from GoI in Sept 06 11.10.2004 2 Shanthikhani Dec’ 2003 EC obtained Submitted to GOI on 26.02.04. 24.01.2006 In principle approval received. PIB note submitted on 01.01.05 3 KTK LW June’ 2005 EMP to be prepared Submitted to GOI 5.08.2005 4 Jallaram Oct’ 2004 Public hearing completed. Submitted to GOI 11.11.04 Application for EC under preparation. 5 Peddampeta Dec’ 2003 Public hearing completed. Submitted to GOI 26.02.04 Application for EC under preparation
  • 106. ADRIYALA SHAFT PROJECT 1. Location : Ramagundam coal belt Ramagundam Area 2. Geological Block : RG SB-II & RG SB-III 3. Geological Reserves : 109.59 Mt 4. Extractable Reserves (Apr.) : 43.38 Mt 5. Area (in Sq.Km) : 3.40 6. Capacity (MTPA) : 2.14 7. Life of the Mine : 31 years 8. Face length : 150m 9. Panel length : 700 - 1300 m 10. Depth range : 294 – 644m 11. Gradient : 1 in 6.0 to 1 in 7.8 :
  • 107. ADRIYALA SHAFT PROJECT Details of seams: Seam Avg. Height of Geological Extractable Grade Thickness Extraction Reserves Reserves (m) (m) (Mt) (MT) I 5.64 3.5 27.99 10.98 E II 3.27 2.0 15.24 6.07 D III 9.40 3.5(Top)/ 43.09 23.31 D 3.5(Bot) IV 3.66 3.5 15.56 11.28 C
  • 108. SHANTIKHANI LONGWALL PROJECT 1. Location : Dorli - Bellampalli coal belt Bellampalli Area 2. Geological Block : Shantikhani Extn Block 3. Geological Reserves : 8.87 Mt 4. Extractable Reserves (Apr.) : 17.78 Mt 5. Area (in Sq. Km) : 6.81 6. Capacity (MTPA) : 1.17 7. Life of the Mine : 23 Years 8. Face length : 150m 9. Panel length : 450 - 2000 m 10. Depth range : 309 – 596m 11. Gradient : 1 in 3.5 to 1 in 5
  • 109. SHANTIKHANI LONGWALL PROJECT Details of seams (Phase-I) Seam Avg. Height of Geological Extractable Grade Thickness Extraction Reserves (Mt) Reserves (m) (m) (Mt) SJ Top 1.88 1.5 18.96 3.91 F SJ Bot 3.18 2.5, 3.5 29.91 13.87 D
  • 110. KAKATIYA LONGWALL PROJECT 1. Location : Mulug coal belt Bhoopalpalli Area 2. Geological Block : Gollapalli block & Peddapur block 3. Geological Reserves : 67.45 Mt (Phase-I)+ 60.06 Mt (Phase-II) 4. Extractable Reserves (Apr.) : 40.02 Mt (Phase-I)+ 35.99 Mt (Phase-II) 5. Area (in Sq. Km) : 9.71 6. Capacity (MTPA) : 2.16 7. Life of the Mine : 24 + 22 Years 8. Face length : 250m 9. Panel length : 1200 - 2900 m 10. Depth range : 35 – 412m 11. Gradient : 1 in 2.8 to 1 in 3.3
  • 111. KAKATIYA LONGWALL PROJECT Details of seams (Phase-I) Seam Avg. Height of Geological Extractable Grade Thickness Extraction Reserves Reserves (Mt) (m) (m) (Mt) IA 2.02 2.0 12.16 7.62 E I 2.66 2.5 17.18 9.45 F II 2.72 2.5 17.55 9.71 F III 3.05 3.0 20.53 13.24 B
  • 112. JALLARAM SHAFT PROJECT 1. Location : Ramagundam coal belt Ramagundam Area 2. Geological Block : RG SB-II 3. Geological Reserves : 206 Mt 4. Extractable Reserves (Apr.) : 79 Mt 5. Area (in Sq.Km) : 7.29 6. Capacity (MTPA) : 2.28 7. Life of the Mine : 53 years 8. Face length : 200m 9. Panel length : 500 - 1800 m 10. Depth range : 123 – 579m 11. Gradient : 1 in 5 to 1 in 8
  • 113. JALLARAM SHAFT PROJECT Details of seams Seam Avg. Height of Geological Extractable Grade Thickness Extraction Reserves Reserves (m) (m) (Mt) (Mt) I 5.09 3.0 53.99 14.13 E II 2.99 2.0 27.43 12.17 E III 8.79 3.0 (Top)/ 85.04 36.91 D 3.5 (Bot) IV 3.00 3.0 29.19 16.21 B
  • 114. PEDDAMPETA SHAFT PROJECT 1. Location : Ramagundam coal belt Ramagundam Area 2. Geological Block : GDK-6B Integrated Mine Block 3. Geological Reserves : 112.62 Mt 4. Extractable Reserves (Apr.) : 41.40 Mt 5. Area (in Sq.Km) : 7.25 6. Capacity (MTPA) : 1.46 7. Life of the Mine : 32 Years 8. Face length : 150m 9. Panel length : 470 - 1200 m 10. Depth range : 118 – 443m 11. Gradient : 1 in 6 to 1 in 10
  • 115. PEDDAMPETA SHAFT PROJECT Details of seams Seam Avg. Height of Geological Extractable Grade Thickness Extraction Reserves (Mt) Reserves (m) (m) (Mt) II 2.64 2.0 24.27 7.06 E III 8.69 2.0 (Top)/ 65.69 21.39 D 3.5 (Bot) IV 2.50 2.5 22.66 12.95 B
  • 116. Variants of Longwall Mining (NEW CONCEPTS)
  • 117. Punch Longwall - Developing longwall panels directly off high walls of OC
  • 118. Punch Longwall Field site operations
  • 119. Punch Longwall Advantages Step change in cost and productivity More production capacity High productivity & low cost Longer term and higher % of reserves extraction Easy logistics – near surface High gate road development rates feasible Higher and faster returns on investment Total investment ~ $100 million – compared with > $300 millions UG
  • 120. Longwall Top Coal Caving (LTCC) Technical Principle Of Top Caving Rock stress 1st pressure Low stress Stress 2nd pressure Compact peak abrupt drop peak stress Pressure curve of top coalseam Fracture Virgin 5600 Coal Broken Coal coal goaf caving 2800 Working Height Front AFC Rear AFC back
  • 121. Longwall Top Coal Caving (LTCC) Supports used
  • 122. Longwall Top Coal Caving (LTCC) Advantages of LTCC • Increased resource recovery in thick seams (> 75%) • Lower face working height (better face control) • Improved spontaneous combustion control • More efficient capital utilisation/ financial performance • Reduced operating costs • Improved production consistency • Less gate road development requirements • Some dust and gas issues
  • 123. LONGWALL – INDIAN PERFORMANCE
  • 124. INDIAN LONGWALL - PAST EXPERIENCE: - Introduction of advanced technology system in Indian coal mining industry marked a major step with the installation of first mechanized Longwall Powered support face at Moonidih in August 1978. - In between 1978 to 1985, a major number of first generation Longwall faces started through out India in various mines of CIL such as Moonidih, Jhanjra, Seetalpur, Dhemomain and Pathakhera Colliery and in SCCL at GDK- 7 & VK-7 Incline.
  • 125. INDIAN LONGWALL - PAST EXPERIENCE: - Churcha Longwall face failed due to dynamic loading. - Jhanjra with shallow depth Longwall working face ran into acute spares problem. - Kottadih face failed after successful completion of two Longwall panels due to dynamic loading and underrated capacity of supports. - GDK.11A failed due to underrated capacity of supports.
  • 126. LONGWALL- SCCL - PAST EXPERIENCE: Longwall technology was introduced in Seven mines of SCCL. Their performance has been: • GDK-10A, JK-5 and VK-7 Incline gave consistently good results, and • The other four mines GDK-7, GDK-9, GDK- 11A and PVK suffered mainly due to non availability of sufficient geological data.
  • 127. INDIAN LONGWALL MAIN REASON : Insufficient geo-technical investigations resulted in surprises by encountering major geological disturbances while working the longwalls. Thus effecting the performance of Longwalls to the maximum extent.
  • 128. INDIAN LONGWALL - PRESENT & FUTURE : - With the likely reduction of contribution from Open cast and the more or less stagnant production from Underground by Conventional methods, it is time that an impetus is given to boost Long wall Technology to able to meet the future energy needs of the country. - On the positive side, coal companies have now gained sufficient experiences right from senior executive level to front line workforce to be able to plan, execute and work longwall faces. What are required are proper geo-technical investigations for effective layout of longwall panels.
  • 129. REASONS FOR POOR PERFORMANCE OF LONGWALL >Large expansion in opencast mining in the past two decades provided cheaper and safe method for bulk coal production and as a result long wall had to take back seat. >Clear strategies were not pursued for its sustenance as there was mixed results from long wall in the early years of its introduction.
  • 130. REASONS FOR POOR PERFORMANCE OF LONGWALL >Long walls were introduced mostly in the blocks left over by working Bord and pillar method. Clean and extensive blocks have not been identified. Even the smaller blocks, which were identified, were of inferior grade coal. >Long wall had to co exist with the conventional mining in most of the mines, which caused management problems. >There were some deficiencies in the imported spares management and the supplies were not reaching in time.
  • 131. REASONS FOR POOR PERFORMANCE OF LONGWALL >Coal companies were sensitive to the failures of a few long wall faces and were not prepared to risk huge investments. >Development could not keep pace with the extraction of Long wall panels, slow progress in dip has delayed the formation of Long wall panels and affected the performance.
  • 132. FUTURE REQUIREMENTS - Longwall should be promoted as a technology mission. - A high level thrust group could be constitute at national level to promote, coordinate and interact different aspects related to Longwall technology.
  • 133. FUTURE REQUIREMENTS - Huge investments incurred on different operations for extraction of coal from greater depths in future can be attained by imposing a special cess on present OC production or from other sources. - R&D efforts are to be doubled. - Efforts are required by the policy makers to transform ideas into actions.
  • 134. FUTURE REQUIREMENTS - Foreign participation is required for extraction of thin seams and steeply inclined seams. - The manufacturing companies of India such as MAMC and Jessop are to be reconstructed/ re-organized. - More number of longwall blocks are to be identified to assure the market for manufacturers.

Editor's Notes

  • #20: HR - no pillar remnants Costs - lower especially support costs Personnel concentrated in one place Training - easier method to learn Roof - can be weak but might affect gateroads Product coal is easy to wash, less fines Ventilation is more concentrated - good air upwind of shearer
  • #21: Baal Bone Colliery Gateroads start from open cut
  • #22: South Bulga is the most productive longwall in Australia (1996) 24,000 tonnes per man year Baal Bone is very productive too
  • #23: Most Gates are TWO Entry Entries are about 5-m-wide Pillar dimensions are 100 m by 35 m Note that 4-way intersections are not used
  • #24: HR - no pillar remnants Costs - lower especially support costs Personnel concentrated in one place Training - easier method to learn Roof - can be weak but might affect gateroads Product coal is easy to wash, less fines Ventilation is more concentrated - good air upwind of shearer
  • #25: Problems such as poor supervision, machinery breakdowns, or rook control have disastrous production consequences. Dust and gas difficult to control because of high production rates. Limited flow area down longwall face limits air quantities for dilution. Conveyor systems too small - get the biggest conveyor money can buy.
  • #26: Advance versus Retreat Longwall Most if not all longwalls are retreat Reserves are well-known. Gateroads are easier to keep open - less support Development operation is totally separate from the longwall Sealing is easier if fire occurs Mine uphill, water runs downhill into the gob Shorter distance for face recovery Better gateroad conditions for ventilation
  • #27: Disadvantages to Retreat over Advance Longwalls are: More money invested in initial gateroad development. - Greater capital cost. Pressure in front of the longwall face can cause gateroad problems Junction of Face and Gateroads is especially critical
  • #32: You need conventional R&P mining equipment first!!! To that add the LW equipment Shields Shearer Face Conveyor CONVEYOR SYSTEM
  • #34: Here is the major equipment Shields or Powered Face Supports Note the articulation and hydraulics The AFC which moves the coal off the face The shearer which cuts the coal and moves it onto the AFC The whole system moves forward Sometimes 10s of meters per day
  • #36: Here is a close-up of a single shield with a section of AFC The Hydraulic Pumps for the shields are located in the headgate ahead of the face. High Pressure hydraulic fluid is delivered via appropriate hoses.
  • #37: The AFC looking at the drive motors on the headgate end. Face is to the left Note the back-plate on the left side of the AFC and the cable tray for electric power to the shearer.
  • #38: A close-up view of the AFC Face is to the left Note back-plate cable-tray drive cog for the shearer
  • #41: Here is the same equipment only underground Note the shearer drum The cut coal is moved by the AFC UNDER the shearer in this case. The AFC is moving into the picture Note the operator carrying a remote control for the shearer
  • #43: Double Ranging-Arm Drum Shearer DRDS for short Shearer rides on the AFC and is COG-DRIVEN (typically) as we saw on the prior slides. Cut coal can pass UNDER the shearer on the AFC RANGING ARMS move the cutter up or down.
  • #44: Shearer Parts Frame Ranging Arms Drive System Hydraulic Motors Electrical Systems Diagnostics Systems
  • #45: Shearer Parts Frame Drive System Cutting System
  • #46: Here is a close-up of that shearer drum. Note the way the main body of the shearer rides on the AFC. Cut coal can pass under the AFC. No bits are in this drum just yet.
  • #47: I am not advertising for anyone, but it is a good photo of a cutter bit with the water spray for dust control. Also the spray helps COOL the bit and reduce the possibility of an ignition.
  • #48: Conveyors are THE MOST IMPORTANT element in getting coal out of the mine. The floor-mounted, rigid-frame conveyor is common for main-line permanent belts. The roof-hung belt with catenary idlers is common for gateroad belts.