The production of metallic silicon adopts the carbon thermal method, which involves smelting silica and carbon reducing agents in a submerged arc furnace. The purity of silicon obtained in this way is between 97% and 98%, which can generally be used for metallurgical purposes. If higher grade silicon is to be obtained, it needs to be further refined to remove impurities and obtain metallic silicon with a purity of 99.7% to 99.8%.
Smelting metal silicon using quartz sand as raw material includes several steps such as making quartz sand blocks, preparing furnace materials, and smelting in a submerged arc furnace.
Generally speaking, high-quality quartz sand can be directly used to produce high-end quartz glass products, and even processed into gemstone grade products such as crystals and tourmalines. Those with slightly lower levels but larger reserves, slightly better mining conditions, and cheaper surrounding electricity are suitable for producing metallic silicon.
At present, the production process route of carbothermal method for the production of metallic silicon in China: generally, silica is used as raw material, Petroleum coke, charcoal, wood chips, low ash coal, etc. are used as reducing agents, smelting at high temperature in a submerged arc furnace, and reducing metallic silicon from silica, which is a slag free submerged arc high-temperature smelting process.
