Rotary kiln refers to rotary calcining kiln (commonly known as rotary kiln), which belongs to building materials equipment category. Rotary kilns can be divided into cement kilns, metallurgical chemical kilns and lime kilns according to different materials. Cement kilns are mainly used for calcination of cement clinker, divided into two categories: dry production cement kilns and wet production cement kilns. Metallurgical chemical kilns are mainly used for the magnetic roasting of lean iron ore in the metallurgical industry; oxidation roasting of chromium and nickel iron ore; roasting high alumina bauxite ore in refractory plants and roasting clinker and aluminum hydroxide in aluminum plants; roasting chrome ore in chemical plants And minerals such as chrome ore powder. Lime kiln (i.e. active lime kiln) is used to roast active lime and light-burned dolomite used in steel plants and ferroalloy plants. Rotary kilns are divided into variable diameter rotary kilns and through-diameter rotary kilns according to their appearance. According to their uses, they can be divided into cement rotary kilns, ceramsite sand rotary kilns, kaolin rotary kilns, lime rotary kilns, etc., according to different energy supply effects. It is a gas-fired rotary kiln, a coal-fired rotary kiln, and a mixed-fuel rotary kiln.