Comminution


Comminution is the reduction of solid materials from one average particle size to a smaller average particle size, by crushing, grinding, cutting, vibrating, or other processes. In geology, it occurs naturally during faulting in the upper part of the Earth's crust. In industry, it is an important unit operation in mineral processing, ceramics, electronics, and other fields, accomplished with many types of mill. In dentistry, it is the result of mastication of food. In general medicine, it is one of the most traumatic forms of bone fracture.
Within industrial uses, the purpose of comminution is to reduce the size and to increase the surface area of solids. It is also used to free useful materials from matrix materials in which they are embedded, and to concentrate minerals.

Energy requirements

The comminution of solid materials consumes energy, which is being used to break up the solid into smaller pieces. The comminution energy can be estimated by:
There are three forces which typically are used to effect the comminution of particles: impact, shear, and compression.

Methods

There are several methods of comminution. Comminution of solid materials requires different types of crushers and mills depending on the feed properties such as hardness at various size ranges and application requirements such as throughput and maintenance. The most common machines for the comminution of coarse feed material are the jaw crusher, cone crusher and hammer crusher. Primary crusher product in intermediate feed particle size ranges can be ground in autogenous or semi-autogenous mills depending on feed properties and application requirements. For comminution of finer particle size ranges machines like the ball mill, vertical roller mill, hammer mill, roller press or high compression roller mill, vibration mill, jet mill and others are used. For yet finer grind sizes, specialist mills such as the IsaMill are used.
Trituration, for instance, is comminution by rubbing. Trituration can further be described as levigation, or pulverization by intervention, which is trituration with a solvent that can be easily removed after the substance has been broken down.