Ball millWikipedia

A ball mill is a type of grinder used to grind and blend materials for use in mineral dressingrevolution and the invention of steam power that an effective ball milling machine could be built.For systems with multiple components, ball milling has been shown to be effective in increasing solid-state chemical reactivity.

Roller millWikipedia

Roller mills are mills that use cylindrical rollers, either in opposing pairs or against flat plates,Roller mills for rock complement other types of mills, such as ball mills and hammermills, in such industries as thepass to maximize extraction of white flour from the endosperm, while removing coarser bran and germ particles.