Ball milling mill charging

Rod and ball mills are cylindrical vessels into which the ore, water, and steel balls or steel rods, called grinding media are charged. The vessels rotate on horizontal axes to cascade the ore and grinding media and thus grind the ore. Typical hall-mill sizes range from 2.5 m in diameter and 3 m in length, driven by a 187-kW motor, up to ca 5 m in diameter and 7 m in length with a 3000-kW drive. 

The preparation in 200-g batches works as follows [6]. A horizontal water-cooled 2-L high-grade steel ball-mill (Simoloyer CMOl) is charged with 2 kg of... 

The second class of grinding equipment is used to prepare dispersions. Typical of this class are ball and pebble mills, ultrasonic mills, and attrition mills. Solids, eg, sulfur, antioxidants, accelerators, and zinc oxide, are generally ground on this equipment (see Size reduction). Ball mill action is assisted in some mills by a combination of dispersion circulation by an external pump and mechanical oscillation of an otherwise fixed nonrotary mill chamber. Where ball mill chambers are rotated it is necessary to experimentally establish an optimum speed of rotation, the size and weight of the ball charge, and ensure the mills do not overheat during the grinding period. 

P.W. Cleary, Predicting charge motion, power draw, segregation and wear in ball mills using discrete element methods, Miner. Eng. 11 (1998) 1061-1080. 

Wet ball-milling is faster than dry-milling and facilitates the separation of the milling media from the charge. Its disadvantage is that the liquid must be removed, which is most economically achieved by filtration, but any soluble constituent will be removed with the liquid. If this is undesirable the alternative is to evaporate the liquid which can be effected by spray-drying if the liquid is water. Evaporation can also take place in shallow trays in ovens in this case soluble material may appear as a skin on the surface and heavy coarse particles may settle out. 

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