Grinding
, in our context here, refers to the operation of reducing the small pieces after crushing to a fine powder. Grinding is accomplished by abrasion and impact of the crushed mineral by the free motion of unconnected hard media such as balls, pebbles, or rods[1]. Examples of grinding include(a) ball mill, (b) roller mill, and(c) impact grinding, illustrated in Figure 17.3.
In a ball mill, hard spheres mixed with the stock to be comminuted are rotated inside a large cylindrical container The motion causes the balls and stock to be carried up