Comminution is the process in which solid materials are reduced in size, by crushing, grinding and other processes. It occurs naturally during faulting in the upper part of the crust
Crust (geology)
In geology, the crust is the outermost solid shell of a rocky planet or natural satellite, which is chemically distinct from the underlying mantle...

 and is an important operation in mineral processing
Mineral processing
In the field of extractive metallurgy, mineral processing, also known as mineral dressing or ore dressing, is the process of separating commercially valuable minerals from their ores.-History:...

, ceramic
A ceramic is an inorganic, nonmetallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous...

s, electronics and other fields. 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
Matrix (geology)
The matrix or groundmass of rock is the finer grained mass of material in which larger grains, crystals or clasts are embedded.The matrix of an igneous rock consists of finer grained, often microscopic, crystals in which larger crystals are embedded. This porphyritic texture is indicative of...

 materials in which they are embedded, and to concentrate minerals.

Comminution energy

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:
  • Rittinger's law, which assumes that the energy consumed is proportional to the newly generated surface area;
  • Kick's law, which related the energy to the sizes of the feed particles and the product particles;
  • Bond's law
    Fred Chester Bond
    Fred Chester Bond was an American mining engineer.-Bond Work Index:He developed the 'Bond Work Index' which relates power consumption in crushing and grinding to the feed and product size distribution...

    , which assumes that the total work useful in breakage is inversely proportional to the square root of the diameter of the product particles, [implying] theoretically that the work input varies as the length of the new cracks made in breakage.
  • Holmes's law, which modifies Bond's law by substituting the square root with an exponent that depends on the material.

Methods of Comminution

There are several manual methods of comminution. Trituration, for instance, is comminution (or substance breakdown) by rubbing. Trituration can further be described as levigation, trituration of a powder with an insoluble liquid, or pulverization by intervention, which is trituration with a solvent that can be easily removed after the substance has been broken down.
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