Mill (grinding) - WikipediaA mill is a device that breaks solid materials into smaller pieces by grinding, crushing, or cutting .. SAG mills are essentially autogenous mills, but utilize grinding balls to aid in grinding like in a ball mill. A SAG mill is . The largest SAG mill is 42' (12.8m) in diameter, powered by a 28 MW (38,000 HP) motor. A SAG mill with a.largest autogenous mills,Autogenous and Semiautogenous mills - The AG/SAG mills are utilized to grind run-of-mine rock or primary . use of large AG/SAG milling allowing to produce the world's largest SAG mill of.