How is silicon metal made, the main grade classification and application areas?

Silicon metal, also known as crystalline silicon or industrial silicon, is mainly used as an additive in non-ferrous alloys.Silicon metal is produced by smelting quartz and coke in the electric heating furnace. The content of main component silicon is about 98% (in recent years, 99.99% Si content is also contained in silicon metal), and the remaining impurities are iron, aluminum, calcium, etc.

Where does the silicon metal come from? 
The production of metal silicon is based on carbon heat, that is, the method of smelting in the mineral heat furnace with silica and carbon reducing agent. The silicon purity of this production is 97% to 98%, so that the silicon can generally be used for metallurgical purposes.
If a higher grade of silicon is to be obtained, it needs to be refined to remove impurities and obtain metal silicon with a purity of 99.7% to 99.8%.
The smelting of metal silicon with quartz sand as raw material, including quartz sand block, preparation furnace material and mineral heat furnace smelting several steps. Generally speaking, high-quality quartz sand will be directly used in the production of high-grade quartz glass products, and even processed into gemstone grade such as crystal, tourmaline and other products. Slightly worse grade but large reserves, slightly better mining conditions, the surrounding electricity is cheaper to produce metal silicon.
At present, China's production of metal silicon carbon thermal method of the production process route: the common use of silica as raw material, petcoke, charcoal, charcoal, low-gray coal, such as reducing agent, in the mineral thermal furnace high temperature smelting, from silicon to restore the metal silicon, which is no slag buried arc high temperature smelting process. Therefore, although metal silicon is extracted from silica, not all silica is suitable for making metal silicon.

The common sand we see every day is not the real raw material for metal silicon, but the quartz sand used in the industrial production described above, and has undergone a multi-step reaction to complete the metamorphosis from sand to metal silicon.

Metal Silicon Grade Classification

Metal Silicon Grade Classification In China, metal silicon is usually classified according to the content of the three main impurities of iron, aluminum and calcium. According to the percentage content of iron, aluminum and calcium in metal silicon, metal silicon can be divided into 553, 441, 411, 421, 3303, 3305, 2202, 2502, 1501, 1101 and other different grades. (About metal silicon number source: first and second code-named iron and aluminum percentage content, third and fourth two represent calcium content.)   For example, 553 represents 5%, 5%, 3%, 3303, which represents 3%, 3%, 0.3% of the iron aluminum calcium content.

Applications for metal silicon?  

Metal silicon (Si) is an industrialpurified monolith silicon, mainly used in the production of silicones, the production of high-purity semiconductor materials, the preparation of special purpose alloys.

1, the preparation of alloy silicon aluminum alloy is the largest amount of silicon alloy. Silicon aluminum alloy is a strong compound deoxive agent, in the process of steelmaking to replace pure aluminum can improve the utilization rate of deoxygenator, and can purify the steel liquid, improve the quality of steel. Silicon aluminum alloy density is small, low coefficient of thermal expansion, casting performance and anti-wear performance is good, with its cast alloy castings with high impact resistance and good high-pressure density, can greatly improve the service life, often used to produce space vehicles and automotive parts. Silicon copper alloy has good welding performance, and is not easy to produce sparks when hit, has explosion-proof function, can be used to make storage tanks.


The addition of silicon to the silicon sheet can greatly improve the magnetic conduction of steel, reduce hysteresis and vortex loss, and can be used to manufacture the core of transformers and motors, and improve the performance of transformers and motors.


2, the manufacture of high-purity semiconductor modern large-scale integrated circuits are almost all made of high-purity metal silicon, and high-purity metal silicon is the main raw material for the production of optical fibers, it can be said that metal silicon has become the basic pillar industry of the information age. 3, the production of silicone rubber, silicone resin, silicone oil and other silicone rubber elasticity is good, high temperature resistance, for the production of medical supplies, high temperature washers. Silicone resins are used in the production of insulating paints, high temperature coatings, etc.


Silicone oil is an oil, its viscosity is very little affected by temperature, used in the production of high-grade lubricants, litors, fluid springs, dielectric liquids, etc., can also be processed into colorless transparent liquid, as a high-grade waterproof ingress sprayed on the surface of buildings.