Industrial silicon (also called crystal silicon) is one of important materials used in modern industrial production. Industrial silicon is widely used in fields of electronics, steelmaking, photics, mechanics, automobile manufacture, chemical industry, metallurgy, medicine, national defense, etc. It is acclaimed as " Industrial monosodium".  Approximately 50% of industrial silicon is applied to manufacture of aluminum alloy. Aluminum-silicon alloy has advantages of good heat stability, high abrasive resistance, and smaller thermal expansion coefficient. Aluminum-silicon alloy is applied to fields of automobile manufacture, aviation industry, electric industry, shipbuilding, etc. Industrial silicon can not only be used as addition agent of nonferrous alloy, but also as alloying agent of high standard silicon steel. It is necessary deoxidizer in steelmaking and smelting of nonferrous alloy. In steelmaking industry, 5 kg of industrial silicon is consumed to produce 1 ton of steel. Chemical grade industrial silicon is raw material for polycrystalline silicon and monocrystalline silicon which are modern high-level technology product needed for integrated circuit development encouraged by the nation. Industrial silicon can be processed into raw material for circuit and electrical components. Japan referred steel, aluminum and semiconductor grade silicon as three main metal materials. Industrial silicon is applied to production of organic compound such as silicone oil, silicon rubber, construction preservative, white carbon black, coating for agricultural plastic film, annexing agent of high quality furniture, annexing agent of decorative painting, annexing agent of ordinary industrial coating, etc. Industrial silicon is also used as reducing agent of certain kinds of metal to produce new type of ceramic metal.