     Back to Products Manufacturing Process Typical Properties Mill Lining BlocksGrinding Media Steatite Grinding Media Calculation of Media Charge Advantages and Applications  Calculations for mill motor power, mill speed and media charge Considering the weight of mill lining and grinding media, work out the motor power required, in consultation with the mill manufacturer.

To calculate media charge for cylindrical mill

Formulae are given below:
1. For batch type ball mill :
M = 0.000691 x D2 x L
where : M = Weight of grinding media charge in kgs
D = Mill Internal Dia in cms. after lining
L = Internal length of the mill in cms. after lining.
2. For continuous type ball mill :
M = 0.000503 x D2 x L
Example - To calculate grinding media charge for a steatite ceramic lined batch type mill size : Dia 6' x 6' Long (Dia 180 cm x 180 cm L) (mill openings are not considered).

Thickness of tapered bricks = 6.5 cms
Thickness of straight bricks = 4.2 cms
Therefore D = 180 - 13 = 167 cms
L = 180 - 8.4 = 171.6 cms
M = 0.000691 x 167 x 167 x 171.6

Grinding media quantity = 3307 kgs
To calculate the motor power required for a cylindrical type ball mill, the following formula can be applied :
W = 0.04116 x D3 x L x n x (0.6d + 0.4d1)
where : W = Required motor power in HP
D = Internal dia of the mill in mtr
L = Internal length of the mill in mtr
d = Specific gravity of grinding media
d1 = Specific gravity of substance
n = Speed of ball mill in rpm.

Example - 1: Let the internal dia of the mill be 1.8 mtr and internal length be 1.8 mtr. If Alumina grinding media is used density d = 3.6. If milling substance is alumina in slurrry form with around 70% solids then d1 = 2.0

Therefore
W = 0.04116 x (1.8)4 x 19 (3.6 x 0.6 + 2 x 0.4) = 24.3 HP
Example - 2: If Steatite grinding media are used to mill the glass frit

d = 2.65 and d1 = 1.6 then,
W = 0.04116 x (1.8)4 x 19 x (2.65 x 0.6 + 1.6 x 0.4) = 18.3 HP
To calculate the speed of the mill, use the following formula:

Nc =
 76.6 ------------------- D1/2

Where : Nc = Critical speed
D = Internal dia in ft.    |