There are two common types of ball mills: grate discharge and overflow discharge

Ball mills accept feed that ranges in seize from 80% passing ¼” with hard ores to 80% passing 1” with softer ores.

Product may be as coarse as 35 mesh or as fine as micron sizes. Grinding is accomplished with spherically shaped grinding media generally made of steel. Grinding action is by point to point contact between balls and shell liners and between the balls themselves.

Material at these points of contact is ground to fine sizes. Mill speed, % solids and ball charge are parameters that affect ball mill grind and tonnage.

Ball mil the length may be less than, equal to or greater than the diameter. A short length takes up less floor space, hast as lower retention time and produces a coarser product. Longer mills have a higher capacity and their greater retention time produces a finer grind with less tramp oversize.