Silicon metal is an important metallurgical raw material, widely used in many fields such as iron and steel, alloy, photovoltaic and so on. The production process of silicon metal mainly includes three main steps: ore dressing, smelting and refining. With the continuous development of science and technology, the manufacturing methods of silicon metal have been continuously improved with the aim of increasing its purity and yield.
three stages
Beneficiation stage
The main ore of silicon metal is quartz, and quartzite has a high silica content that can reach over 95%. Beneficiation refers to the separation of useful minerals from the raw ore and the removal of impurities from them. The beneficiation process is divided into two types: dry and wet. Dry beneficiation generally uses simple physical methods for separation, such as differences in color and density. Wet beneficiation, on the other hand, requires dissolution or flotation methods to chemically extract useful minerals.
smelting stage
Smelting is a process in which the ore obtained from beneficiation is subjected to a series of heating and chemical reactions to obtain silicon metal. The commonly used smelting method is electric furnace smelting. Furnace smelting involves the reduction of silica in quartz ores to silicon metal by means of electricity. The smelting process involves high temperature heating, so the smelting equipment needs to have high heat resistance. The smelting process also produces a large amount of carbon dioxide and sulfur dioxide and other harmful gases, which need to be treated and discharged.
Refining Stage
Refining refers to the further purification of the smelted silicon metal to remove impurities. The common methods used in the refining process are nitric acid leaching and solvent extraction. Nitric acid leaching method is to use nitric acid to treat silicon metal and remove the impurities. Solvent extraction method is to use the solvent solubility properties, the silicon metal dissolved in the solvent, and then through the extraction to separate impurities. The refining process also needs to control the temperature and the amount of solvent to ensure the refining effect and product quality.
The production process of silicon metal may have certain environmental problems. Its production process generates a large amount of slag and wastewater, which should be treated and recycled in accordance with the relevant regulations by the producers to minimize the negative impact on the environment.
