Matching Pairs GRINDING MACHINESOnline version Types of Mills by Jhony Guillermo Montesinos Cossio 1 SAG Mill 2 Ball Mill 3 Autogenous Mill 4 Rod Mill 5 What is a mill? 6 High Pressure Roll Mill It is an acronym for semi-autogenous grinding that also uses grinding balls like a ball mill. It is a device that breaks solid materials into smaller pieces by grinding, crushing, or cutting. Such comminution is an important unit operation in many processes.