Stone Grinders: 1. High capacity. 2. Wide size range of final product 3. National dust-dump standard. The Stone Grinders are mainly used in grinding more than 280 noninflammable and nonexplosive materials with a Moth's hardness below 7 scale, a humidity below 6%, such as barite, calcite, potash, pencil stone, marble, limestone, ceramic, glass and other materials which used in mining, construction ...