Industrial silicon production
Large scale production of silicon is done by reduction of quartz with carbon. The necessary high temperatures of about 2000 °C are processed by an electric arc in a reduction furnace.
A mixture of quartz and different carbon materials (coal, coke or charcoal) is continuously fed into the furnace. From the furnace tap hole liquid silicon is extracted with a temperature of about 1600°C. The metal is further processed by oxidative refining, casting, crystallization and crushing.
The purity of metallurgical silicon is about 99%. Typical impurities that come from the raw materials are iron, aluminum, calcium and titanium.