What s the difference of Ball mill SAG mill AG mill Jan 11 2018· Attrition mill is a type of grinding mill by kinds of media to crush lump to powder like substances The impact can be rock on rock such as in an Autogenous Grinding AG mill rock and a small ball charge 10% used in Semi Autogenous Grinding SAG mills balls of various sizes in Ball Mills and less commonly these days steel rods in Rod Mills