Cyclone - JK.pdf

Hydrocyclones

Hydrocyclones

Hydrocyclones

O 1. Cyclone Operating VariablesO 2. Efficiency CurvesO 3. Nageswararao ModelO 4. Fish Hook EffectO 5. Density EffectsO 6. Fitting the ModelO 7. Limitations of the Model

Hydrocyclones

Hydrocyclone Terminology

Feed inlet

Conical section

Apex

Cylindrical section

Vortex finder

Feed chamber

Hydrocyclones

Hydrocyclone Flow Patterns

Feed

Overflow

Underflow

Inner flow spiral(upwards)

Outer flow spiral(downwards)

Hydrocyclones

Forces on Particles

O CentrifugalO DragO Gravity

Hydrocyclones

Separation VariablesParticle Properties

O size O shape O s.g.

Hydrocyclones

Separation VariablesFluid Properties

O density O solids presentO viscosity

Hydrocyclones

Separation VariablesMachine Properties

O inlet area O diameterO cylinder lengthO cone angle O vortex finder diameter O spigot diameter O vortex finder lengthO angle of inclination

Hydrocyclones

Efficiency Curves - I

0.00.10.20.30.40.50.60.70.80.91.0

0.01 0.10 1.00 10.00

Size (mm)

F

r

a

c

t

i

o

n

t

o

C

o

a

r

s

e

ActualEfficiency

Curve

Hydrocyclones

Efficiency Curves - II

0.00.10.20.30.40.50.60.70.80.91.0

0.01 0.10 1.00 10.00

Size (mm)

F

r

a

c

t

i

o

n

t

o

C

o

a

r

s

e

D50 Act

Actual

WaterSplit

Hydrocyclones

Short Circuit Model

Feed

CoarseProduct

FineProduct

ShortCircuit

TrueClassification

Remainder

Hydrocyclones

Efficiency Curves - III

0.00.10.20.30.40.50.60.70.80.91.0

0.01 0.10 1.00 10.00

Size (mm)

F

r

a

c

t

i

o

n

t

o

C

o

a

r

s

e

D50 Act

D50 Corr

ActualCorrected

Hydrocyclones

Efficiency Curves - IV

0.00.10.20.30.40.50.60.70.80.91.0

0.1 1 10

D/D50c

F

r

a

c

t

i

o

n

t

o

C

o

a

r

s

e

ReducedEfficiencyCurve

Hydrocyclones

Efficiency Curve Model - I

2)(

)1(C = E50

)50o(

+

ee

e

cddcd

d

Hydrocyclones

Efficiency Curve - Varying

0 .0

0 .1

0 .2

0 .3

0 .4

0 .5

0 .6

0 .7

0 .8

0 .9

1 .0

1 1 0 1 0 0 1 0 0 0

S iz e ( m )

F

r

a

c

t

i

o

n

t

o

F

i

n

e

0 .2 50 .512357 .51 0

Hydrocyclones

Reduced Efficiency Constant for a Given Mineral

Hydrocyclones

D50 Equation

65.0 01

15.02.05.0

12

)((93.0

47.052.0

250 22.0

=

=

=

DKK

DL

DDKK

DDu

DDK

Dd

DD

c

c

c

iDD

gDP

cc

oD

c

c

cp

Hydrocyclones

Recovery to Underflow - I

22.024.0

50.0

12

27.053.040.219.1

2 )(

c

c

c

iww

cpc

u

c

owf

DL

DDKK

gDP

DD

DDKR

=

=

Hydrocyclones

Recovery to Underflow - II

22.024.0

25.0

12

31.083.194.0

2 )(

c

c

c

ivv

cpc

u

c

ovv

DL

DDKK

gDP

DD

DDKR

=

=

Hydrocyclones

Pressure-ThroughputEquation

1.0 01

2.01.045.012

68.05.02

)()(

)()(2

=

=

=

cQQ

c

c

cQQ

c

o

pcQ

DKK

DL

DDiKK

DDPDKQ

Hydrocyclones

Fish Hook Effect - I

0

0.2

0.4

0.6

0.8

1

10 100 1000Size (m)

F

r

a

c

t

i

o

n

t

o

F

i

n

e

Hydrocyclones

Fish Hook Effect - IIO Exaggerated in graphO Assumed originally to be caused by changing

size measurement techniqueO With advent of wide size range measurement

techniques (Laser etc) - phenomenon really occurs sometimes

O Assumptions about short-circuiting of particles with water breaking down

O High viscosity and large cyclones???

Hydrocyclones

Efficiency Curve Model - II

E = C(1+

o( )d

d cc

dd c

dd

e

e e50

50

50

1

2

+

*

*

)( )

( )

Hydrocyclones

Efficiency Curve - Varying

0 .0

0 .2

0 .4

0 .6

0 .8

1 .0

1 .2

1 .4

0 .1 0 1 .0 0 1 0 .0 0 1 0 0 .0 0 1 0 0 0 .0 0S ize (m )

F

r

a

c

t

i

o

n

t

o

F

i

n

e

0 .00 .20 .51 .02 .0

Hydrocyclones

JKSimMet Cyclone Parameters - I

Geometry Data

Hydrocyclones

JKSimMet Cyclone Parameters - II

Model Parameters

Hydrocyclones

JKSimMet Cyclone Parameters - III

Performance Data

Hydrocyclones

SG Effects - 1

0.00.10.20.30.40.50.60.70.80.91.0

10 100 1000

Size (m)

F

r

a

c

t

i

o

n

t

o

F

i

n

e

GalenaSphaleriteSilica

d50c (Ga) d50c (Sp) d50c (Si)

Hydrocyclones

SG Effects - 2

0.00.10.20.30.40.50.60.70.80.91.0

10 100 1000

Size (m)

F

r

a

c

t

i

o

n

t

o

F

i

n

e

GalenaSphaleriteSilicaAverage

d50c (Ga) d50c (Sp) d50c (Si)

Hydrocyclones

O KD0 depends on feed solids characteristics only -size & sg

D50 Equation - II

cc dmd 50mineral

feed50

1-sg1-sg =)(

Hydrocyclones

Fitting the Cyclone Model - I

O Use measured pressure wherever possibleO If in doubt about measured pressure, compare

with manufacturers tablesO Make sure the Measured Pressure is available to

Model Fitting by activating it on the Equipment Data Tab of the Model Fit Dialog window

O Typical values of KQ0 are 300 - 600

Hydrocyclones

Fitting the Cyclone Model - II

O KD0 is typically 0.001 - 0.00001O Actual water split to O/F is fitted rather than

KV1 and KW1 (both controlled by the water split)O You can calculate an estimate of the water split

from the mass balanced water flow dataO Always fit the Water Split

Hydrocyclones

Fitting the Cyclone Model - III

O If the fit is poor at fine sizes, try setting to 0.1. If this improves the fit, then fit .

O Plotting and inspecting the efficiency curve will help (Remember that you need data in the cyclone feed combiner port to plot efficiency curves)

Hydrocyclones

Design Considerations - I

O Cut Size Cyclone Diameter

smaller > finer

Operating Pressure higher > finer

Feed Density lower > finer

Inclination flatter > coarser

Hydrocyclones

Design Considerations - II

O Water split to overflow higher > more efficient90% not usually achievable

Hydrocyclones

Design Considerations - III

O Feed Size coarse feeds limit water split to O/F fine feeds increase viscosity cant create fine material in cyclone

O Pressure controls wear in pump and cyclone trade-off between wear and operational flexibility

Hydrocyclones

Design Considerations - IV

O Operation at high overflow density capital v operating trade off

capital thickeners are expensive

operating higher operating pressure smaller cyclones larger mill

Hydrocyclones

Cyclone Model Limitations I

O Feed size effect As the feed becomes coarser, d50c tends to decrease

even when all the other variables are kept constant.O Efficiency curve equation

The analytic form used does not provide a perfect representation for the reduced efficiency curve.

Hydrocyclones

Alternative Efficiency Curve Model

d/d50(corrected)

%

o

f

F

e

e

d

t

o

O

v

e

r

f

l

o

w

(

c

o

r

r

e

c

t

e

d

)

0

20

40

60

80

100

120

140

160

180

0.00 0.50 1.00 1.50 2.00 2.50

Efficy. curve at 0.33xd50c

Efficy. curve at d50c

Efficy. curve at 0.66xd50c

Hydrocyclones

Cyclone Model Limitations II

O Viscosity Viscosity variations due to changes in pulp density

are largely accounted for by the model. Viscosity variations caused by variable quantities of

slimes affect the parameters in quite a systematic way.

Hydrocyclones

Cyclone Model Limitations III

O Increasing viscosity causes coarser cut size water split to overflow reduced pressure drop increased reduced efficiency curve constant till roping

Hydrocyclones

Cyclone Model Limitations IV

O Effect of roping cut size increased by 5 to 10 alpha value reduced to 0.1 - 0.2 water split not affected much pressure drop not affected much inclination allows operation at higher underflow

density before roping

Hydrocyclones

Cyclone Model Limitations V

O Prediction of roping difficult SPOC constraint

feed density

Plitt constraint underflow size distribution

O JKSimMet warns when either constraint is violated

Hydrocyclones

Cyclone Model Limitations VI

O SPOC Constraint

at sg 2.7 at sg 4.0Feed

DensityUnderflow

DensityFeed

DensityUnderflow

DensityFeed

DensityUnderflow

Density% by Volume % by Weight % by Weight5 53 12.4 75.3 17.4 81.8

10 54 23.1 76.0 30.8 82.415 55 32.3 76.7 41.4 83.020 56 40.3 77.5 50.0 83.625 57 47.4 78.2 57.1 84.130 58 53.6 78.8 63.1 84.735 59 59.2 79.5 68.3 85.2

Hydrocyclones

Cyclone Model Limitations VII

O Plitt constraint

Roping onset% Solids by Vol.

Underflow50% passing (m)

% Solidsat sg 2.7

% Solidsat sg 4.0

35.2 50 59.4 68.539.0 60 63.3 71.945.9 80 69.6 77.250.5 100 73.4 80.353.9 120 75.9 82.458.6 170 79.3 85.060.0 200 80.2 85.761.3 250 81.0 86.4

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Cyclone - JK.pdf