Australian Coal Preparation Society DENSE MEDIUM CYCLONE WORKSHOP Presented By: J.A. Engelbrecht JUNE 2011

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 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 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 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 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


Cyclone Constraints


US Bureau of Mines

Cyclone Constraints


A Swanson

Cyclone Constraints


US Bureau of Mines

DESCRIPTION SIZE

FEED 0.33 x D Inlet = DMax

HANGUP SIZE 0.7x DMax

BREAKAWAY SIZE See Graph



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



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





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



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



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



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





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



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


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


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


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 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


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


Normalised Epm and Relative Cut Density - Jigs


Operational ParametersPressure

Medium

Density Control

Cut Density

Distributors


J Steyn


J Steyn

Operational ParametersMedium

G J de Korte


RD = 1.5

RD = 1.06

RD = 3.0


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


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


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


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


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



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


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


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



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

THANKYOU

Documents

Australian Coal Preparation Society DENSE MEDIUM CYCLONE WORKSHOP Presented By: J.A. Engelbrecht JUNE 2011