Smelting process of silicon for chemical industry

The process flow of chemical silicon includes furnace material preparation, electric furnace melting, refining and casting of silicon, and crushing by removing slag inclusions. Before the preparation of furnace materials, all raw materials must undergo necessary treatment. Silica is crushed in a jaw crusher to a size of no more than 100mm, and fragments smaller than 5mm are screened out and washed clean with water. Because the fragments in the furnace melt in the upper part of the furnace, the permeability of the furnace material is reduced, making the production process difficult to carry out. Petroleum coke has a high conductivity. It should be broken to a block size of no more than 10mm, and the amount of Petroleum coke powder should be controlled. Due to its direct combustion at the furnace mouth, it can cause insufficient reducing agent.
In the production of chemical silicon, bituminous coal can completely replace charcoal, such as refined washed bituminous coal from Zhuzhou, Hunan. The fixed carbon content is 77.19%, volatile matter is 19.4%, ash content is 3.41%, Fe2O3 content is 0.22%, Al2O3 content is 0.99%, and CaO content is 0.17%. Through production practice, it is feasible to use this type of bituminous coal to smelt chemical silicon.
The wood blocks and chips used in the production of chemical silicon are processed using cutting machines and chip chippers. The carbonaceous reducing agent in the furnace charge is mainly Petroleum coke and bituminous coal, and the amount of wood blocks and chips depends on the furnace condition. In production, wood is not used, and instead, the product quality is more stable. The proportion of furnace materials is determined based on the required product grade. The ratio of Petroleum coke and bituminous coal is determined according to the carbon required by each batch of ore silicon. The ratio of Petroleum coke to bituminous coal has a great influence on the working resistance of furnace charge.
After weighing each component of the furnace material, mix the furnace material evenly. After compacting the furnace, concentrate the evenly mixed furnace material into the furnace. Maintain a certain height of the material surface and feed evenly.
Chemical silicon production is continuous. The condition inside the furnace is not eternal. The production of chemical silicon in an electric furnace is the process of converting electrical energy into thermal energy, which is then directly heated by the thermal energy to produce a chemical reaction. So the electrical characteristics inside the furnace are very important. The smelting adopts closed arc operation to maintain a high temperature furnace, improve thermal efficiency, and improve the utilization rate of the electric furnace. In the research, one metal silicon furnace with a capacity of 3200KVA and one metal silicon furnace with a capacity of 6300KVA were used. The smelting process is carried out by using a certain period of braising and periodic centralized feeding. Under normal circumstances, it is difficult for the furnace material to sink automatically, and forced sinking is generally required. The furnace condition is prone to fluctuations and difficult to control. Therefore, it is necessary to make correct judgments and handle them in a timely manner during production. Every 4 hours, the furnace is discharged for refining and casting, and the broken slag is sorted and stored.