raymond mill

　　Comminution (size reduction) in mining and mineral processing is necessary to unlock or liberate minerals from the waste rock (gangue). Comminution of material begins at the mining stage using explosives, excavators or scrapers to generate materials that are easily transportable by haul trucks or conveyors. Crushing is the second step in the comminution of mined materials and is carried out to produce particles of a given size distribution and particle shape in preparation for grinding the last stage in the comminution process.

　　Grinding mills utilize one or more methods to achieve particle size reduction/shape including compression, impact, abrasion and attrition. Choosing a grinder type is dependent on the material type and properties, amount of size reduction required, particle shape, particle distribution, throughput, maintenance, energy requirements and overall processing cost per ton. Grinders are often categorized as coarse, fine and ultra fine, with particle size getting progressively smaller. Common types of grinding mills include AG mills, SAG mills, rod mills, ball mills, pebble mills, vibratory mills, high pressure grinding rolls, and stirred media mills. Grinding mills come in all sizes, from laboratory use and small scale pilot plants to full production continuously run equipment.