Silicon metal, also known as crystalline silicon or industrial silicon, is mainly used as an additive for non-ferrous alloys.
Silicon metal is a product smelted from quartz and coke in an electric furnace. The main component silicon content is about 98%, and the remaining impurities are iron, aluminum, calcium, etc. In my country, metal silicon is usually classified according to the content of three main impurities: iron, aluminum and calcium.
According to the percentage content of iron, aluminum and calcium in metal silicon, metal silicon can be divided into different grades such as 553, 441, 411, 421, 3303, 3305, 2202, 2502, 1501, 1101 and so on. In each brand, the first and second codes represent the percentage content of iron and aluminum, and the third and fourth two digits represent the content of calcium, so 553 represents the content of iron, aluminum and calcium in metal silicon is 0.5%, 0.5% , 0.3%; 441 represents that the content of iron, aluminum and calcium in metal silicon is 0.4%, 0.4%, and 0.1%. It can be seen that the difference between 441 and 553 is the difference in purity. The silicon content of 553 is ≥ 98.7%, while the silicon content of 441 ≥99.1%, specifically, industrial silicon is obtained by high-temperature reaction of quartz and carbon in a submerged arc furnace: SIO2+C=SI+CO2.
Quartz has poor quality and quality, and carbon as a reducing agent also has poor quality and quality. The difference in these raw materials determines the purity of industrial silicon.