Australian Coal Preparation Society DENSE MEDIUM CYCLONE WORKSHOP Presented By: J.A. Engelbrecht...
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Transcript of Australian Coal Preparation Society DENSE MEDIUM CYCLONE WORKSHOP Presented By: J.A. Engelbrecht...
Australian Coal Preparation Society
DENSE MEDIUM CYCLONE WORKSHOP
Presented By: J.A. Engelbrecht
JUNE 2011
Contents
DMC ProcessDense Medium Cyclones
Cyclone DesignPerformance ConstraintsDMC Factors
Operational ParametersWashabilityFlow SheetsFine DMC SeparationConclusions
DMC ProcessTypical DMC Process Flow Sheet
Typical Dense Medium Process Flow Sheets
Coal Process
DMC Flow Sheets
Typical Dense Medium Process Flow SheetsDMC Flow Sheets
Efficiency Test
- Measure System Efficiency
- Sampling Standards on Large Capacity Screens?
- Sampling Error Bars?
Inside a Dense Medium ProcessDMC Flow Sheets
Dense Medium Cyclones
Cyclone DesignCyclone Dimensions: DSM vs. Multotec
Effect on Efficiency
Effect of Cyclone Configuration
DSM Formula for Cyclone of Standard Configuration
• Inlet = 0.2 x D
• Vortex Finder = 0.43 x D
• Spigot = 0.7 x V.F (0.3 x D)
• Cone Angle = 20 Deg.
• No Barrel Section
Formula gives the total Volumetric Capacity of the cyclone as a function of the Feed Head
Cyclone Dimensions: DSM vs. Multotec
Cyclone Design
Cyclone Dimensions: DSM vs. Multotec
Cyclone Design
Tangential Involute Scrolled Evolute
Cyclone type DSM Multotec
Diameter D D
Inlet 0.2xD – Tangential
0.2xD,0.25xD,0.3xD – Scrolled Evolute
Cone Angle 20 Degrees 20 Degrees
Vortex finder 0.43xD 0.43xD,0.5xD
Spigot 0.7xVF 0.7xVF, 0.8xVF
Barrel No Yes
Cyclone Dimensions: DSM vs. Multotec
Cyclone Design
Scrolled Evolute Entry
- Increases capacity by 20 %
B, AB and A Inlets
A and XA Vortex Finders
Barrel Section
- Increase Capacity by 5 -10%
Cyclone Dimensions: DSM vs. Multotec
Cyclone Design
Cyclone Design influences the capacity and therefore explains the deviation from the DSM standard
Multotec Standard Capacity Cyclones Multotec High Capacity Cyclones
Cyclone Diameter (mm)
Max Particle Size (mm)
Coal Feed (t/h)Cyclone
Diameter (mm)Max Particle Size
(mm)Coal Feed (t/h)
510 34 54 510 51 99
610 41 81 610 61 145
660 44 97 660 66 175
710 47 114 710 71 207
800 53 149 800 80 270
900 60 196 900 94 355
1000 67 249 1000 100 454
1150 77 351 1150 115 638
1300 87 468 1300 130 854
1450 97 608 1450 145 1108
Cyclone Dimensions: DSM vs. Multotec
Cyclone Design
Effect of Cyclone Configuration
Cyclone Design
Inlet Head - Particle Size - Cyclone Capacity
Vortex Finder - Spigot : VF < 0.8 : 1
Spigot - Based on minimum M:O ratio of 1.5:1
Barrel - Cyclone Capacity - Cyclone Efficiency
Pressure - Cyclone Capacity
Performance ConstraintsCyclone Constraints
Factors Influencing Performance
A DMS Cyclone is sized with reference to three Criteria
The size of cyclone selected will be the largest needed to satisfy all three of the following:
1. Volumetric Capacity
2. Top Size
3. Spigot Capacity
Cyclone Constraints
Performance Constraints
STREAM M:O RATIO
FEED ≥ 3
OVERFLOW ≥ 2.5
UNDERFLOW ≥ 1.5
Cyclone Constraints
Performance Constraints
Cyclone Constraints
Performance Constraints
US Bureau of Mines
Cyclone Constraints
Performance Constraints
A Swanson
Cyclone Constraints
Performance Constraints
US Bureau of Mines
DESCRIPTION SIZE
FEED 0.33 x D Inlet = DMax
HANGUP SIZE 0.7x DMax
BREAKAWAY SIZE See Graph
Factors Influencing Performance
Performance Constraints
Cyclone Efficiency Curves
0.00
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.10
0.11
0.12
0.13
0.14
0.15
0.16
0.17
0 1 2 3 4 5 6 7 8 9 10
Particle Size (mm)
Ge
ne
ralis
ed
Ep
m
1450
1300
1150
1000
900
800
710
660
620
610
570
510
470
420
390
360
250
FIGURE 14
Factors Influencing Performance
Performance Constraints
Breakaway Size vs Cyclone Diameter (mm)
4.99
6.28
7.67
9.18
0.22 0.36 0.510.93 1.07
1.20 1.651.45
1.99
2.222.28
2.522.85
3.46
4.20
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
10.00
100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400
Cyclone Size (mm)
Bre
ak
aw
ay
Siz
e (
mm
)
FIGURE 12
Factors Influencing Performance
Performance Constraints
Factors Influencing Performance
Performance Constraints
A Swanson
Centrifugal Acceleration vs Cyclone Diameter
30.0
35.0
40.0
45.0
50.0
55.0
60.0
100 1000
Cyclone Diameter (mm)
Ce
ntr
ifu
ga
l Ac
ce
lera
tio
n
FIGURE 10
Factors Influencing Performance
Performance Constraints
Cyclone Diameter vs. Feed Size Distribution
15
2125
28
3639
42
47
53
59
68
77
86
0
10
20
30
40
50
60
70
80
90
100
0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600
Cyclone Size (mm)
B/A
way
Siz
e an
d T
op
Siz
e (m
m)
Break away size (mm) Top Size (mm)
Recommended Size Distribution Limits
Factors Influencing Performance
Performance Constraints
Cyclone DIameter vs. Feed Size Distribution vs. Capacity
0
10
20
30
40
50
60
70
80
90
100
0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600
Cyclone Size (mm)
B/A
way S
ize a
nd
To
p S
ize (
mm)
0
200
400
600
800
1000
1200
1400
1600
1800
2000
Flo
w R
ate
(m
^3
/hr)
Break away size (mm) Top Size (mm) Capacity (m3/hr)
•Large Particles require large diameter cyclones which requires large volumes
• If solids feed rate is low then alternative equipment must be considered
Factors Influencing Performance
Performance Constraints
Cyclone DIameter vs. Feed Size Distribution vs. Capacity
0
10
20
30
40
50
60
70
80
90
100
0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600
Cyclone Size (mm)
B/A
way S
ize a
nd
To
p S
ize
(m
m)
0
200
400
600
800
1000
1200
1400
1600
1800
2000
Flo
w R
ate
(m
^3
/hr)
Break away size (mm) Top Size (mm) Capacity (m3/hr)
•High solids feed rate require large cyclone diameters
• If feed grading is very fine, multiple smaller diameter cyclones must be considered
Factors Influencing Performance
Performance Constraints
Factors Influencing Performance
Performance Constraints
Underflow Capacity
- M:O Ratio ≥ 1.5
- Volumetric Split = F(Du/Dvf)
- Maximum Du/Dvf = 0.8
JKMRC
• Spigot size determined by mass recovery to underflow
• Once selected,
Spigot:Vortex finder ratio needs to be checked
• Spigot diameter also affects differentials
Spigot Size ( Ratio of Vortex Finder Size )
0.01
0.011
0.012
0.013
0.014
0.015
0.6 0.65 0.7 0.75 0.8 0.85 0.9
Spigot to Vortex Finder Ratio
EP
M V
alu
e
- Normal Spigot = 0.7 x VF
- High Capacity Spigot = 0.8 x VF
Factors Influencing Performance
Performance Constraints
DMC FactorsNormalised Epm
Relative Cut Density
Figure 1: Partition Curve
0
20
40
60
80
100
1.20 1.25 1.30 1.35 1.40 1.45 1.50 1.55 1.60
Relative Density
Rec
ove
ry t
o C
lean
Co
al [
O/F
]
EPM75/25 = 0.030
EPM90/10 = 0.0625
EPM95/5 = 0.085
DMC FactorsNormalised Epm
Figure 2. Actual EPM Values for Low and High Density Separations
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
1.20 1.30 1.40 1.50 1.60 1.70 1.80 1.90 2.00 2.10
Relative Density
Pa
rtit
ion
Nu
mb
er
D50 = 1.80
D50 = 1.35
EPM = (1.369 - 1.337) / 2 = 0.016
EPM = (1.822 - 1.779) / 2 = 0.0215
Actual EPM = A + B p W /d A = Constant B = Constant, f( Medium Characteristics) p =RD W = Loading d = Particle Size
DMC FactorsNormalised Epm
Figure 3 : Normalised EPM Values for Low and High Density Separations
0.00
0.20
0.40
0.60
0.80
1.00
0.80 0.90 1.00 1.10 1.20
Relative Density
Par
titi
on
Nu
mb
er
D50 = 1.35
D50 = 1.8
(1.369 - 1.337) / ( 2 * 1.8 ) = 0.012
(1.822 - 1.779) / ( 2 * 1.35 ) = 0.012
DMC FactorsNormalised Epm
Figure 5 : Cyclone Efficiency Curves
0.000.010.020.030.040.050.060.070.080.090.100.110.120.130.140.150.160.17
0 1 2 3 4 5 6 7 8 9 10
Particle Size (mm)
No
rma
lis
ed
Ep
m
1450
420
DMC FactorsNormalised Epm
DMC FactorsRelative Cut Density
Figure 6 : Particle Size vs Relative Cut Density
0.98
1.00
1.02
1.04
1.06
1.08
1.10
0 5 10 15 20 25 30 35 40
Particle Size
Rel
ativ
e C
ut
Den
sity
DMC FactorsRelative Cut Density
Figure 7. Particle Size vs Normalised EPM and Relative Cut DensityCyclones
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0 5 10 15 20 25 30 35 40
Particle Size
No
rma
lise
d E
PM
1
1.01
1.02
1.03
1.04
1.05
1.06
1.07
1.08
1.09
Re
lati
ve
Cu
t D
en
sit
y
EPM Relative Cut Density
DMC FactorsRelative Cut Density
Normalised Epm and Relative Cut Density - Jigs
DMC FactorsRelative Cut Density
Operational ParametersPressure
Medium
Density Control
Cut Density
Distributors
Operational ParametersPressure
J Steyn
Operational ParametersPressure
J Steyn
Operational ParametersMedium
G J de Korte
Operational ParametersMedium
RD = 1.5
RD = 1.06
RD = 3.0
Operational ParametersMedium
If differentials are too big, hang-up of particles can occur
Two Types of Hang-Up can Occur
Hang – Up of Coarse Sinks Particles• Diamond Industry – Concern• Other Applications – Accelerated Wear• Thought to be caused by Medium Instability• Can be overcome by increasing the spigot size
Hang – Up of Tramp Metal• Caused by irregular shape and size• Can be overcome by increasing the spigot size• Use Cast Iron Cones
Operational ParametersMedium
Poor Control
Operational ParametersDensity Control
Operational ParametersDensity Control
F Breedt
Factors Affecting Cut Density– Medium stability– Operating pressure– Cyclone size– Spigot size
In order for parallel cyclones or modules to have the same cut densities the following is required:– Cyclone dimensions must be equal– Medium properties must be the same– Pressure must be equal– Feed rate must be equal– Surface moisture must be equal– Distribution must be equal
Operational ParametersCut Density
Operational ParametersDistributors
Washability
Near Density
Organic Efficiency
Cyclone Results
Organic Efficiency = Actual Yield Theoretical Yield
WashabilityOrganic Efficiency
WashabilityNear Density
Defined as -
The % (Dx) of NEAR DENSITY material which lies within ± 0.1 RD intervals on either side of the Separation Density.(New standard +/- 0.05)
Dx, % Degree of Difficulty 0 – 7 Simple 7 – 10 Moderate Difficult
10 – 15 Difficult15 – 20 Very Difficult20 – 25 Exceedingly Difficult
> 25 Formidable
WashabilityNear Density
Gondwanaland Coals
0
5
10
15
20
25
1.3 1.4 1.5 1.6 1.7 1.8 1.9 2
Density
Perc
enta
ge
Increase in Cut density = Increase in EP value
WashabilityNear Density
Gondwanaland Coals
0
5
10
15
20
25
1.3 1.4 1.5 1.6 1.7 1.8 1.9 2
Density
Perc
enta
ge
Effect of Poor Efficiency
WashabilityNear Density
Laurasion Coals
0
5
10
15
20
25
1.3 1.4 1.5 1.6 1.7 1.8 1.9 2
Density
Perc
en
tag
e
Different Coal Sources = Different Approaches / Recommendations
WashabilityNear Density
WashabilityNear Density
D W Horsfall
800mm Cyclone4 Seam
800mm Cyclone2 Seam
Separation Density 1.48 1.60
Circ Medium RD 1.42 1.52
Ecart Probability 0.02 0.03
Ave Particle Size 7.00 7.00
Near Density Material 25.30 8.40
Theoretical Yield 38.80 79.82
Organic Efficiency 89.55 99.10
Sink in Float 4.87 1.31
Float in Sink 4.91 1.68
Total Misplaced 9.77 2.99
Actual Yield 34.74 79.11
Quality 28.00 28.00
WashabilityCyclone Results – Various Seams
WashabilityCyclone Results - MAX1450
Flow Sheets
Basic Flow Sheet
Design Parameters / Inputs
Split DMC Flow Sheet
Idealised Flow Sheet
Australia Southern Africa
0
5
10
15
20
25
30
35
40
45
50
1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4
Density%
In C
lass
28 mm 8 mm 2 mm 0.71 mm
0
10
20
30
40
50
60
1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6
Density
% I
n C
lass
20 mm 4 mm 1.41 mm 0.71 mm 0.22 mm 0.07 mm
Flow SheetsDesign Parameters / Inputs
Medium Density
Screen 1 Aperture
Hydro Cyclone D50 Feed PSD
Cyclone Diameter
1.35 0.7 mm 0.07 mm Fine 420 mm
1.425 1.5 mm 0.1 mm Medium 900 mm
1.5 3 mm 0.13 mm Coarse 1450 mm
Hydrocyclone Screen 1
Rf 0.05 0.05
alpha 1.7 6
Size Ep Cut Density
1.18 0.10 1.68
0.71 0.10 1.68
0.22 0.14 1.88
0.07 1.02 2.14
In all cases the plant was fed 1000 tph
0
10
20
30
40
50
60
70
80
90
100
1 10 100
Size (mm)
% P
assi
ng
Coarse Medium Fine
Flow SheetsDesign Parameters / Inputs
Sizing
Spirals
Cyclone Classifier
Screen 1
Spiral
Large DMS CycloneFeed minus 50mm
DMS Product
DMS Reject
Minus 50 plus x mm
Screen 1 fines
Spiral Product
Plus y microns
minus x mm
Spiral Reject
Minus y microns
Flotation Product
Flotation cells
Flotation Tails
Flow SheetsBasic Flow Sheet
Cyclone Classifier
Screen 1
Spiral
Large DMS CycloneFeed minus 50mm
DMS Product
DMS Reject
Minus 50 plus x mm
Screen 1 fines
Spiral Product
Plus y microns
minus x mm
Spiral Reject
Minus y microns
Flotation Product
Flotation cells
Flotation Tails
Flow SheetsBasic Flow Sheet
Cyclone Classifier
Screen 1
Spiral
Large DMS cyclone
Feed minus 50 mm
DMS Product
DMS Reject
Small DMS cycloneScreen 2
Minus x mm
plus z mm
Spiral Product
Plus y microns
minus z mm
Spiral Reject
Minus y microns
DMS Reject
Minus 50 plus x mm
Flotation Product
Flotation cells
Tails
DMS Product
Flow SheetsSplit DMC Flow Sheet
Flow SheetsSplit DMC Flow Sheet
Cyclone Classifier
Screen 1
Spiral
Large DMS cyclone
Feed minus 50 mm
DMS Product
DMS Reject
Small DMS cycloneScreen 2
Minus x mm
plus z mm
Spiral Product
Plus y microns
minus z mm
Spiral Reject
Minus y microns
DMS Reject
Minus 50 plus x mm
Flotation Product
Flotation cells
Tails
DMS Product
Flow Sheets
With Flotation
Without Flotation
Southern Africa 41.8 29.9 45.6 36.4Australia 77.3 62.9 82.8 71.4Southern Africa 48.2 31.8 53.3 38.9Australia 77.4 57.5 84.5 72.2Southern Africa 42.6 30.2 48.7 37.2Australia 77.6 63.2 83.4 71.4Southern Africa 49.5 40.2Australia 84.4 71.4
Cyclone Size
Range
Base Line
Standard Split DMS
Liberation
With Flotation
Without Flotation
Cyclone Classifier
Screen 1
Spiral
Large DMS cyclone
Feed minus 50 mm
DMS Product
DMS Reject
Small DMS cycloneScreen 2
Minus x mm
plus z mm
Spiral Product
Plus y microns
minus z mm
Spiral Reject
Minus y microns
DMS Reject
Minus 50 plus x mm
Flotation Product
Flotation cells
Tails
DMS Product
X ≈ 5mm
Z = 0.1 to 0.3mm
y=?mm
Maybe even consider desliming before flotation. The issue of moisture content to be balanced against energy recovery
Optimise the Feed PSD
Flow SheetsIdealised Flow Sheet
Flow SheetsConclusions
SA ore more variable than Australian ore in terms of process parameters
Increased liberation improved the overall yield and quality– This is valid for both Australian and Southern African Coal– However if there is no flotation, finer crushing has an
adverse effect on the yield of an Australian coal, due to loss of fine coal
– The quality does improve for finer crushing
Sending a larger size range to the fine cyclones has a beneficial impact in terms of coal quality and quantity (There is also the benefit of additional control)– This is less pronounced on Australian coal, when there is
no flotation
Flow SheetsConclusions
Controlling Medium density has an inter-play between coal quality and yield
Splitting the circuit into a fines DMS and a coarse DMS has the benefit of independently controlling the cut density and medium to ore ratios of the two circuits – This is of considerable benefit when there is a variable ore
body
Using smaller cyclones has a beneficial impact in the fines circuit – The effect of the cyclone size for the large fraction in the
split circuit was insignificantly small
Fine DMC Separation
Conclusions
Summary
Fine DMC SeparationSummary
Fine DMC SeparationSummary
Fine DMC SeparationSummary
Test Plant at South Witbank Colliery
Flow SheetsIdealised Flow Sheet
G J de Korte
The fine circuit enables dense medium separation to be extended to particles as small as 0.2mm.
Dense medium separation is more efficient and flexible than water based equipment like Spirals, TBS or WOC.
It also highlights that a combination of water only processes can provide better overall results.
Fine DMC SeparationConclusions
Conclusions
DMC separation is very efficient even for large diameter cyclones
It is doubtful whether the current operating standards can fully utilize the potential efficiency of DMC on a continuous basis
There is merit to consider a split DMS circuit i.e. coarse and fine
Finer crushing may give better overall results DMS is the most efficient and flexible process down to 0.5mm
or even 0.2mm
Efficiency tests measures the total system and depends on a number of parameters
Fine DMC SeparationConclusions
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