Matching Pairs GRINDING MACHINESOnline version Types of Mills by Jhony Guillermo Montesinos Cossio 1 Ball Mill 2 SAG Mill 3 What is a mill? 4 Autogenous Mill 5 Rod 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.