Silicon metal, also known as industrial silicon or crystalline silicon, is usually produced by carbon reduction of silicon dioxide in electric furnaces. Its main use is as an additive for non-ferrous alloys and as a starting material for the production of semiconductor silicon and organosilicon.
In China, silicon metal is usually classified according to the content of the three main impurities it contains: 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. The first and second digits are coded for the percentage content of iron and aluminum, and the third and fourth digits represent the content of calcium. For example, 553 means that the content of iron, aluminum and calcium is 5%, 5%, 3%; 3303 means that the content of iron, aluminum and calcium is 3%, 3%, 0.3%)
The production of silicon metal is made by carbothermal method, which means that silica and carbonaceous reducing agent are smelted in the ore furnace. The purity of the silicon produced in this way is 97% to 98%, and such silicon can generally be used in metallurgical purposes. If you want to get a higher grade of silicon, you need to refine it to remove impurities, and get a purity of 99.7% to 99.8% of metallic silicon.
Smelting silicon metal with quartz sand as raw material includes several steps of quartz sand block making, charge preparation and ore furnace smelting.
In general, high-quality quartz sand will be directly used in the production of high-grade quartz glass products, and even processed into gem grade such as crystal, tourmaline and other products. The grade is slightly worse, but the reserves are larger, the mining conditions are slightly better, and the surrounding electricity is cheaper, which is suitable for the production of silicon metal.
At present, China’s production of silicon metal carbon thermal production process: the general use of silica as raw materials, petroleum coke, charcoal, wood chips, low ash coal and other reducing agents, in the ore thermal furnace high temperature smelting, reducing silicon metal from silica, which is a slag free submerged arc high temperature melting process.
Therefore, although silicon metal is extracted from silica, not all silica is suitable for making silicon metal. The ordinary sand we see everyday is not the real raw material of silicon metal, but the quartz sand used in the above-mentioned industrial production, and it has undergone a multi-step reaction to complete the disintegration from sand to silicon metal.
Post time: Dec-04-2024
