Mechanical screening, often just called screening, is the practice of taking granulated ore material and separating it into multiple grades by particle size.. This practice occurs in a variety of industries such as mining and mineral processing, agriculture, pharmaceutical, food, plastics, and recycling. [A method of separating solid particles according to size alone is called screening]
This illustrates the approach to crusher sizing (as well as giving an exercise in identifying the balances). The approach is described in detail in Mular and Jergensen (1982) and Mular et al. (2002). Crusher suppliers, of course, have propriety methods of selecting and sizing units for a given duty.