Rotary kiln belongs to building material equipment, which can be divided into cement kiln, metallurgy chemical kiln and lime kiln according to different materials. Cement kiln is used for making of cement clinker and there are dry and wet methods to make cement. metallurgy chemical kiln is used for magnetic roasting of iron ore and oxidizing roasting of chrome and nickel in the steel factory; baking high-alumina mine in the refractory material factory; baking chamotte and alumina in the aluminium factory and baking chrome ore and chrome powder in the chemical plant.