The invention relates to a method of filling carbon in the bottom of furnace during the smelting of silicon metal
In the process of electric furnace smelting of silicon metal, the batching is the first process, the amount of carbon used in each batch directly affects the economic and technical indexes of each phase, and the carbon consumption is a key control index in the process of electric furnace smelting of silicon metal. When there is insufficient carbon in the furnace, silica cannot be fully reduced, and excessive silica generates a large amount of silicon monoxide in the furnace. Part of the excess silicon dioxide becomes liquid and slagged together with impurities in the raw materials, making the furnace conditions change. When there is a surplus of carbon in the furnace, silicon carbide will be produced in the furnace, which floats in the oxides of silicon metal to improve the viscosity of the melt, resulting in the furnace slag is difficult to remove out of the furnace, too much carbon will also improve the low temperature conductivity of the charge and reduce the charge resistance, resulting in electrode lifting. In actual production process, silicon metal furnace smelting furnace reaction process can be divided into the following areas: (1) the low temperature reaction area (below 1100 ° C) in the high temperature reaction gas, to escape from the material surface traces of the SiO contact with oxygen in the air, the following reaction Si 1/2 = 0 + SiO2 (1) under 1100 ° C the SiO is not stable, may also the following reaction 2 si0 = Si02 + Si (2) but activity in reducing agent on the surface, Give priority to the following reaction the SiO + C = SiC + CO (3) (2) generate the SiC area (1100, 1800 ° C), reaction (3) from 1100 ° C has been able to undertake more strongly, to 1537 ° C, can carry out the following spontaneous reaction Si02 + 3 C = SiC + 20 (4) and (3) to generate the melt silicon area (above 1400 ° C), at about 1400 ° C silicon melting (e.g., to generate a lower melting point of Si - Fe alloy), after more than pure melting point, the SiO reaction with carbon, Si SiO+C = Si+C0 From 1650°C, the following reaction will proceed to the right for Si02+2SiC = 3Si+2C0) SiC decomposition area (above 1800°C), and the following reaction will proceed to the right for Si02+2SiC = 3Si+2C0 at a higher temperature, due to reaction of SiC and SiO, the decomposition will produce silicon and carbon monoxide. (5) the SiO evaporation area (above 2000 ° C), from 1750 ° C, the reaction to the right of the following Si02 + C = Si0 + C0 today when the ingredients while through theory combined with practical experience in sufficient carbon reductant, but due to loss of reductant in low temperature reaction zone is more, most of the reducing agent before entering the generation of silicon melt area before end of reaction, into the production of silicon melt area reduction low doses, furnace bottom caused by lack of charcoal, long-term furnace bottom lack of charcoal, a large surplus of silica is formed after melting viscous slag, difficult to eliminate, will cause the furnace bottom rising, electrode inserted not easily, The air permeability of the material surface becomes worse, which directly affects the production.
