HGM series Three-rings and Medium-speed Micro-powder Grinding Mill is a new type grinding mill for micro-powder making, widely used in making fine powder or ultra-fine powder. It is suitable for grinding calcite, limestone, dolomite, kaolin, bentonite, talc, illite, pyrophillite, barite, meerschaum, fluorite, potash ore and other more than 200 kinds of materials that Moh's hardness is below 6, non-explosive, non-flammable minerals. When users grind the material that hardness degree is between 4 and 6, the service life of the spare parts will be shortened.