Ball mills consist of the following components:
Inlet – crushed ore is fed to the ball mill through the inlet. A scoop ensures the feed to the mill is constant.
Discharge – reduced feed exits the mill through the discharge.
Drum – the drum is the cylindrical casing of the ball mill. The inside of the drum is fitted with manganese steel alloy plates (‘armour’) that protect the steel shell from abrasion; it is also possible to use rubber as armour rather than manganese steel.
Ring Gear – a gear ring installed on the outer periphery of the drum.
Electric Motor – a motor used to rotate the drum. The motor drive train leads to a gearbox than a ring gear. The motor is usually fitted with a variable speed drive (VSD) to control the rpm of the ball mill.
Gearbox – used for speed reduction from the motor to the ball mill.
Balls – usually manufactured from manganese alloy steel, but the material depends upon for what material the mill will grind (chrome steel alloy and rubber also available). The size of the balls depends upon the size of the drum, typical ball sizes are two to three inches in diameter (four-inch balls are also possible).
Bearings – smaller ball mills use anti-friction cylindrical roller bearings. Larger ball mills use trunnion bearings.
