To calculate media charge for batch mill. M = 0.000929 x D2 x L

where :
M = Grinding media charge in kgs
D = Internal Dia of the Mill in cms. after lining
L = Internal length of the mill in cms. after lining.

To calculate grinding media charge for continuous type ball mill, M = 0.000676 x  D2 x L
Example - To calculate grinding media charge for a 180 cm dia x 180 cm long batch type ball mill with Duralox 50 mm thick bricks.

Formula to be used is
M = 0.000929 x D2 x L
D = 180 - 10 = 170 cms
L = 180 - 10 = 170 cms

Therefore M = 0.000929 x (170)2 x 170
Grinding media quantity = 4564 kgs.