nareen,Sivart has given a good description of what a ball mill...

nareen,
Sivart has given a good description of what a ball mill is, although his second paragraph is definitely "tongue in cheek"!
It doesn't hurt for people not associated in any way with the mining industry to get a bit of a feel for whats going on in minerals processing. So picture a very large (usually) steel drum, rotating on a horizontal axis, driven by a very powerful electric motor. Lining the inside of the drum are very hard (special alloy iron) replaceable liners, to slow down (but never prevent) wear and tear, and protruding bars called lifters set in the liners. Only a certain percentage of the inside volume is occupied by the ore and cast iron mill balls, so the mixture is free to "flop around" in there. As the drum rotates, the lifters lift the material on one side of the drum, and when they can no longer hold onto it, gravity takes over and it falls to the bottom of the drum, crushing the ore to an ever smaller size. Simple but effective.
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