Ball Charge Design Methods

Grinding Course

Ball Charge Design Methods

• Polysius for Finish Mills A formula that covers the entire mill as though it is a

single compartment mill.

• Slegten For Finish Mills Rules for 1st Compartment and “Transition Zone” Formula for Remainder of 2nd Compartment

Polysius Ball Charge for Finish Mills

xeD 13.96

D = Ball Diameter , mm

X = Distance From Feed End of Mill, m

Polysius Ball Charge Design

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

90.00

100.00

110.00

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Distance From Feed End of Mill, m

Bal

l Dia

met

er, m

m

Ball Sizes

0.6250.6316

0.750.7920

10.9825

1.251.1830

1.51.5740

21.9750

2.52.3660

2.752.7670

33.1580

3.53.5490

approx std size, inchBall Dia, inchBall Dia.,mm

Example of Polysius Ball Charge

100.00 100.009.5Total C2

0.0049990.0000.625

32.33495531.5830.75

0.0048860.0001

31.53483231.5831.25

15.62478815.791.51.5

20.52471821.0522

   0.5Partition

100.00 100.004Total C1

25.00450025.0012.5

25.00450025.0012.75

25.00450025.0013

25.00450025.0013.5

% by wt.Bulk Density,

kg/m3% by VolMill Length,mBall Dia, in

Slegten Ball Charge For Finish Mills

• Use 90 mm Balls for 20% (by wt.) of 1st Compartment Charge.

• Use Same number (“n”) of 80,70, and 60 mm Balls for Remainder of 1st Compartment Charge.

• Use “n” number of 50 and 40 mm Balls in 2nd Compartment. (Transition Zone)

• Fill Remainder of 2nd Compartment According to:

• D = Ball Dia., mm

• X = Distance from Transition Zone, m

xeD 1.33

Slegten FM Ball Charge Design For Fine Grinding Zone

y = 33e-0.1x

0

5

10

15

20

25

30

35

0 1 2 3 4 5 6 7 8

Distance From End Of Transition Zone, m

Bal

l Dia

., m

m

Compartment 1 - Polysius vs Slegten

Ball Charge Comparison,1st Compartment, 4m Dia by 4 m Length

0.0

10.0

20.0

30.0

40.0

3.5 3 2.75 2.5

Ball Sizes, inch

% o

f 1s

t C

om

par

tmen

t C

har

ge

Mas

s

Polysius

Slegten

Compartment 2 - Polysius vs Slegten

Ball Charge Comparison, 2nd Compartment, 4m Dia. By 9.5 m Length

0.00

10.00

20.00

30.00

40.00

2 1.5 1.25 1 .75 .625

Ball Size, inch

% o

f 2nd

C

om

par

tmen

t C

har

ge

Mas

s

Polysius

Slegten

Slegten vs Polysius

Comparison of Slegton and Polysius Ball Charges

00.5

11.5

22.5

33.5

4

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Distance From Mill Feed End, m

Bal

l d

iam

eter

, In

ch

Slegten

Polysius