Comminution

The process ofsize reduction is known as comminution. In mineral processing parlance, comminution in coarse range is known as crushing and in fine range it is called grinding.
Generally, crushing is carried out in two stages, namely, primary and secondary crushing. Jaw and Gyratory type crushers are used mostly for primary crushing. They are characterized by wide input side (known as gape) and narrow discharge. They can handle large tonnage of material. Jaw crushers produce a reduction ratio of 4:1
to 9:1 while gyratory crushers produce a somewhat larger range of 3 : I to 10:1. The reduction ratio is defined
as the representative feed size by representative product size.