The process of burning into clinker under the high temperature of a rotary kiln. Therefore, the rotary kiln is the main machine in cement production, commonly known as the "heart" of cement plants. In the building materials industry, in addition to calcining cement clinker, active lime is also used for calcining clay, limestone, and slag drying; in the production of refractory materials, rotary kiln calcination raw materials are used to stabilize the size and increase strength , And then processed. In nonferrous and ferrous metallurgy, iron, aluminum, copper, zinc, tin, nickel, tungsten, chromium, files and other metals are smelted and roasted with rotary kiln as the smelting equipment. For example: it is used in the production of aluminum to roast aluminum hydroxide into alumina; it is used in ironmaking to produce pellets for blast furnace ironmaking; foreign "SL / RN method" and "Krupp method" are used to iron ore Direct reduction; chlorinated volatile roasting method is used to extract tin and lead.