... Mill is to grind materials in the fields of building materials, mining, metallurgies and chemical industry. The materials should be non-flammable ... and non-explosive. Examples of the materials are: quartz, feldspar, barite, fluorite, dolomite, garnet, carborundum, bauxite, ... so on(400 kinds of materials). The materials should have the hardness less than 9.3 in Moh’s scale and ...