Pilot plant testing for hydrocyclone design

By:
R.Mazahernasab
Feb2013
PILOT-PLANT TESTWORKS
FOR HYDROCYCLONE
CIRCUIT DESIGN

 Introduction
 Design variables
 Hydrocyclone efficiency
 Hydrocyclone design
 Testworks
CONTENT
2

 A hydrocyclone is a size classifier used to
process slurries.
 The separation mechanism is based on
enhanced gravity and takes advantage of
particle size and density.[5]
INTRODUCTION
3
 Recovery of water to overflow is
generally high (around 90%). It follows
that the coarser particles exit through
the underflow as a dense slurry.[5]

INTRODUCTION
Slurry is injected into the
cylindrical zone
Cycloning starts to take
place in the feed
chamber.
Heavier particles move
to the outer walls by
centrifugal forces and
move toward the apex.
Lighter particles stay near the
center of the cone and are carried
away by the vortex finder.
[1,7]

 Classification does not take-place throughout the whole body
of the cyclone.
5
INTRODUCTION
Region A: unclassified feed
Region B: fully classified coarse material
Region C : fully classified fine material
Region D: classification takes place.
Across this region, decreasing sizes show
maxima at decreasing radial distances
from the axis.[1]

 Hydrocyclone design objectives:
 Maximum efficiency
 Maximum capacity
 Lower operating costs
 The process design criteria will be based on an interpretation
of testwork carried out on the particular ore.
 As more test work result are available and the ore
characteristics and process become better defined a
continuous updating of the design criteria is under taken.
 Pilot scale testing is regerded as the most reliable method of
selecting flowsheets and generating design criteria for
equipment sizing and selection.[4]
6
INTRODUCTION

Cyclone geometry
Area of the inlet
nozzle
Cyclone diameter
Cylindrical and
conical section
Vortex finder and
apex orifice
Feed features
Solids concentration
and Size distribution
Specific gravity of solid
and liquid
Slurry and liquid viscosity
Initial pressure of feed
7
DESIGN VARIABLES
Cyclone performance
0.05 times the
cyclone diameter
squared
−Retention time
−Length equal to
cyclone diameter
−Angle:10°- 20°
[1],[2]

 The sharpness of the cut depends on the slope of the central
section of the partition curve; the closer to vertical is the
slope, the higher is the efficiency.[1]
8
HYDROCYCLONE EFFICIENCY

 Small cyclone diameters give greater efficiency.
 Efficiency and P increase with height; normally height is
between 2 and 6 diameters.
 Smaller cone angle gives better efficiency.
 Pressure drop is related to efficiency, It increases with
efficiency.
 In practice the efficiency is limited because at high
P, velocities become high, and turbulence causes re
entrainment and loss of particles.
 Efficiency increases with mass which increases with particle
size.[1,6]
9
HYDROCYCLONE EFFICIENCY

EFFICIENCY, FLOWRATE AND P
0
0
water Flowrate, Q
0
ΔP,mofwatercolumn
Efficiency
A
B
Optimum
Operation
Eff
P
Theory
Practice
40
100
[6]

 You should start with calculating cyclone diameter:
Step1: Calculate required D50 using mass balance equations
from known information.
Step2: Calculate D50(base) with multiplying times a series of
correction factors designated by C1, C2, and C3:
D50C(application) = D50C(base)xC1xC2xC3
o C1: influence of the concentration of solids
11
HYDROCYCLONE DESIGN
[2],[3].[4]

Larger amount of fines
coarser separation
Absence of fines
finer separation 12
HYDROCYCLONE DESIGN
 this is affected by particle
size and shape and liquid
viscosity.
 higher concentration
results coarser separation.
[2]

o C2: influence of pressure drop
• Pressure drop is a measure of the energy being utilized in the
cyclone to achieve the separation.
• It is recommended that pressure drops, be designed in the 40
to 70 kPa range to minimize energy requirements. [2]
C2 = 3.27 x ∆P-0.28
13
HYDROCYCLONE DESIGN

14
HYDROCYCLONE DESIGN
 Higher pressure
drop finer
separation [2]

o C3: Influence of specific gravity of the solids and liquid
 GS = Specific gravity of solids
 GL = Specific gravity of liquid
[2]
15
HYDROCYCLONE DESIGN

D = 0.204 x (D50(base))1.675
 [2]
16
HYDROCYCLONE DESIGN
D50(base) = D50C(application)/C1xC2xc3

 Then determine cyclone capacity and number of
cyclones:
 The volume of feed slurry that a given cyclone can handle is
proportional to the pressure drop.
Number of cyclone= total slurry flow rate /cyclone capacity.
 Approximately 20% to 25% standby cyclones are
recommended for operational as well as maintenance
flexibility. [2],[3]
17
HYDROCYCLONE DESIGN

 Determine apex diameter: [2]
19
HYDROCYCLONE DESIGN

 Vortex finder diameter:
where Dv is the vortex diameter and Dc is cyclone diameter
 Inlet nozzle diameter:
[3]
20
HYDROCYCLONE DESIGN
Di = 0.05 × (Dc)2

 Sizing Measurement Tests
 Sizing analyses provide useful information on the size
distribution of a sample of ore or other material, using a
comprehensive set of screens and all screening done under
standard and unvarying conditions to ensure self-consistency
and reproducibility of the results.[8]
21
TESTWORKS

 X-ray Diffraction (XRD):
Qualitative Identification - mineral present
Semi-Quantitative analysis - identification and
estimation of major/minor/trace components
Quantification of mineral species present - Rietveld
quantification[8]
 The solids Specific gravity of the equivalent Mineral is:[9]
22
TESTWORKS

 Testwork 1: To collect the data on the operational
performance of hydrocyclone, a series of pilot scale tests was
conducted.
 These experiments were carried out using feed slurry
consisting of quartz
 particles with a density of 2650 kg/m3. The feed size
distribution is shown in Table 1.
23
TESTWORKS

 The liquid phase was water.
 A hydrocyclone of 100 mm diameter and 435 mm total
length, at a constant inlet pressure of 10 psi was used.
 The variable parameters were; the overflow opening diameter
in the range of 14–50 mm, the middling flow opening
diameter in the range of 4–12 mm, and the underflow
opening diameter in the range of 10–24 mm.
 The inlet opening diameter was kept constant at 14 mm with
all other conditions.[10]
24
TESTWORKS

 Test rig
 Fig. 11 shows a schematic diagram of the test rig used in the
experimental work.
 It comprises a 100 hydrocyclone, a variable speed slurry
pump and 80 l baffled sump.
 The pressure drop across the cyclone was measured with a
pressure gauge using a diaphragm mounted on the feed inlet
pipe.
 Stirring of slurry in the sump was achieved by a mechanical
agitator in conjunction with the turbulence created by the
returning flows and baffles which ensured a complete
suspension of solids in the sump.[10]
25
TESTWORKS

26
TESTWORKS
Fig. 11. A schematic
diagram of the test rig
constructed at the
Mineral Processing
Laboratory, Faculty of
Engineering, Assiut
University.[10]

 Test procedure, sampling and data analysis
 In each test, the appropriate components are selected to
obtain the desired hydrocyclone configuration.
 Feed slurry containing approximately 4.8% solids was
prepared in the sump. After attaining steady state
condition, the overflow, middling flow and underflow streams
were sampled simultaneously for a certain time.
 This is immediately followed by sampling of the feed stream.
The slurry samples are weighed, filtered, dried and reweighed
to calculate the flow rates and solids percent in the different
products.
 The obtained results were mass balanced and used for
subsequent calculations and interpretations.[10]
27
TESTWORKS

 Testwork 2: Particle size distribution of the dispersed phase
 A proper amount of tracer particles as the dispersion phase
and the continuous phase was mixed in the feed tank and
pumped into the pipe line with a centrifugal pump.
 A return line was set near the inlet of the pump to manipulate
the feed rate and to avoid the strong impact to the
hydrocyclone by the inlet flow.
 The light dispersion was separated and went back to the tank
with the overflow, while the continuous phase went back to
the tank directly with the underflow.
 The position of the orifices in the hydrocyclone was
determined by the research purpose. [11]
28
TESTWORKS

 For the study of the influence of the vortex finder’s structure
parameter on the flow distribution, some representative and
uniformly distributed axial cross-section should be chosen to
set the orifices.
 The weighting method was used to test the separation
efficiency under the same material system.[11]
29
TESTWORKS

 The results give a coordinated relationship of vortex finder
parameters and performance of hydrocyclones for separating
light dispersed phase.
 The size of vortex finder has great influence on the
distribution of the centrifugal separation factor, but the
different depth of vortex finder has little influence on the
centrifugal separation factor.
 With the reduction of the vortex finder diameter, the size of
the dispersed particles gets smaller and the separation of the
hydrocyclone gets better. [11]
30
TESTWORKS

 Testwork3: Effect of particle size and shape on hydrocyclone
classification
 The hydrocyclone tests were carried out as follows: 30 L of the
slurry, in the slurry tank was circulated by the circulation pump
through the circulation line to agitate and disperse the particles
in the slurry.
 After the slurry flow through the hydrocyclone reached a steady-
state, the overflow product (hereafter referred to as OP) from the
vortex finder and the underflow product (UP) from the apex of the
cyclone were sampled in plastic bottles.
 the flow rates of the overflow and underflow were measured
using measuring cylinders and a stopwatch.
 Both the overflow and underflow products were dried, and the
solids were weighed for calculations of the solid concentrations
of the OP and UP as the solid mass per unit volume of the
samples.[12]
31
TESTWORKS

 Size distributions of particles contained in the OP and UP
samples were measured using a laser-diffraction-dispersion-
type particle size distribution analyzer, Microtrac MT3300SX
(Microtrac Inc.), with the measurement condition:wavelength
of light source, 780 nm;measured range of particle
size, 0.021–1408 μm; measuring time, 30 s; refractive
index, 1.55 for PTFE, 1.51 for glass flake, 1.33 for water;
measure mode, transparent and nonspherical.
 The results in the table suggest that the settling velocity of
large particles is smaller than that of small particles when
the particle Reynolds number is large.
 In the hydrocyclone tests of PTFE and glass flake, recovery of
coarser particles as underflow product decreased at high inlet
velocities.[12]
33
TESTWORKS

 [1] will’s mineral processing technology, eddition7
 [2] THE SIZING AND SELECTION OF HYDROCYCLONES, Richard A. Arterburn
 [3] mineral processing, Dr. Nematollahi
 [4] mineral processing plant design practice and control,I
 [5] Fundamental understanding of swirling flow pattern in
hydrocyclones, Aurélien Davailles a,b,⇑, Eric Climent a,b, Florent Bourgeois
c
 [6] apresentation: Powder Technology – Part II, DT275 Masters in
Pharmaceutical and Chemical Process Technology, Gavin Duffy, School of
Electrical Engineering Systems, DIT
 [7] a presentation: An Introduction to Basic Hydrocyclone Operation
 [8] JK hydrocyclone test
 [9] DESIGNING AND TESTING THE REPRESENTATIVE SAMPLERS FOR
SAMPLING A MILLING CIRCUIT AT NKANA COPPER/COBALT
CONCENTRATORChibwe, P.1, Simukanga, S.1, Witika, L.K.1,Chisanga, P.2
and Powell, M. 2005
35
REFERENCES

 [10] Performance of a three-product hydrocyclone Mahmoud M. Ahmed
a,, Galal A. Ibrahim a, Mohamed G. Farghaly b, 2008
 [11] The coordinated relationship between vortex finder parameters and
performance of hydrocyclones for separating light dispersed phase Qiang
Yang, Hua-lin Wang∗, Jian-gang Wang, Zhi-ming Li, Yi Liu, 2011
 [12] Effect of particle shape on hydrocyclone classification Kouki
Kashiwaya , Takahiko Noumachi 1, Naoki Hiroyoshi, Mayumi Ito, Masami
Tsunekawa, 2012
36
REFERENCES

Pilot plant testing for hydrocyclone design

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