The ball mill is a key equipment for grinding materials, widely used in powder-making production line such as cement, silicate sand, new-type building material, refractory material, fertilizer, ore dressing of ferrous metal and non-ferrous metal, glass ceramics, etc. Ball mill can grind various ores and materials with dry type or wet type. There are two kinds of ball mills, grate type and overfall type due to different ways of discharging material.