The main raw materials for silicon metal are quartz (silica), petroleum coke, and wood chips. The silicon is produced through electric furnace smelting.
1
The raw material quartz is first washed, screened, and dried. Based on the type of reducing agent used, the materials are proportioned accordingly. The proportions are controlled by a computer program. Then, the materials are collected from their respective silos onto a conveyor belt, where they are mixed evenly during the feeding process and fed into the electric furnace. The feeding process is highly automated and operates on a continuous large-scale basis.
2
Electric current is applied to the electrodes, heating the materials inside the furnace to temperatures above 1800°C. Silicon is reduced inside the furnace and becomes molten. It is then discharged through a tapping port and cast into silicon ingots. These ingots are crushed and packaged according to customer requirements.
3
A bottom-blowing refining method is used, involving a mixture of oxygen and air. Permeable bricks for oxygen injection are installed at the bottom of the ladle. These bricks contain many fine copper tubes through which oxygen and air are blown into the molten silicon for refining. After oxygen blowing is completed, air continues to be blown in to maintain positive pressure in the molten silicon. The refining process requires stirring, which is carried out using compressed air.
