... three-rings and medium-speed micro powder grinder is a new type of making micro powder machines through more than twenties ... -rings and medium-speed micro powder grinder is widely used in making fine powder or micro powder, and the raw materials should ... Moh's hardness less than 6 grade such as limestone, calcite, dolomite, kaolin, bentonite, talc, illite, pyrophillite, barite, meerschaum, fluorite, ...