Hi Yogesh,

If the mill is static, then there can be no flow of product.

In a working mill there is dynamic movement. What comes in must go out. Product and metal is carried up the side of the mill, sometimes assisted by lifter strips, which creates a head, causing flow. It is not essential for the mill to be inclined to create flow.

Regards - John.rz ■

In a ball Mill material is fed, and the product discharged, in a continuos flow. In the course of size reduction, the material moves from intet to the outlet of the mill.This motion is due to several factors. In dry grinding these are:

1: increase in bulk volume of material as it is ground to finer particle size. (curves are available for bulking (increase in volume) of feed material with increasing fineness in a mill.

2: increasing flowability of material as it is more finely reduced.

3: Displacement of fine material with better flow properties by the course feed materialwith poor flowability.

The feed area and discharge diaphragm in the mill are frequently provided with lifting / conveying scoops. The discharge device removes the material and discharges it into trunions. The fines with better flow characteristics replace them causing a flow.

This information is available in any reasonably good handbook. I am sure engineering offices have these handbooks. I used refer to Taggarat in sixties and still refer to it when need arises. There are some handbooks in the field of Cement manufacture. and now there is google. ■

Dear Yogesh,

In dry grinding, material is transported through the mill by medium-high velocity air that is injected at the inlet or mill feed end. As the mill rotates, mineral critical size fines are brought to the ball charge surface and are suspended and liberated by the injected air velocity currents and swept out the exit port.

In wet grinding, finely ground ore is transported via water injected into the mill inlet. There is a small gradient of higher hydraulic head, at the feed end, which produces a slurry current, starting at the feed end, and which picks up viscosity (fines) as it passes through the mill full of balls to the overflow exit at the opposite end. There is also a difference in ball sizes (segregation) between feed and overflow exit that aids flow. There is a ball screw separator which keeps balls in the mill while allowing the mineral laden slurry to pass the mill exit overflow dam. ■