Crushing is a crucial process before mineral processing. The crushing of ore involves reducing the particle size of the ore lumps from large to small, during which various useful mineral particles are liberated. Crushing ore improves mineral processing efficiency. In crushed ore, some minerals that were originally intergrowth separate along their interfaces, becoming small particles containing only one mineral, called liberated single-mineral particles. However, some small mineral particles remain intergrowths of several minerals, called intergrowth particles.

The degree of liberation of a mineral refers to the ratio of the number of liberated individual particles of that mineral to the sum of the number of intergrowth particles containing that mineral and the number of liberated individual particles of that mineral. This result is expressed as a percentage. If the grinding product is too coarse, the ore will not be sufficiently liberated, which will affect the concentrate grade and recovery rate of the selected ore. However, if the ore is ground too finely, although it will promote sufficient mineral liberation, it will also produce more fine particles that are difficult to separate, causing mineral loss, i.e., “over-grinding”. “Over-grinding” not only does not have a beneficial effect on the separation process, but also reduces the concentrate grade and recovery rate. Moreover, because excessive grinding does “unnecessary work”, it increases the consumption of equipment, manpower and other aspects in the grinding and separation processes, indirectly increasing the cost of mineral processing.

Therefore, maintaining an appropriate grinding fineness in the mineral processing process is an important condition for achieving good separation of valuable minerals and gangue minerals. Mineral processing plants should pay attention to the selection of grinding processes and equipment, strictly control the operating conditions of grinding and mineral processing, and strictly control the grinding fineness within the range determined by mineral processing tests.