factors affecting coal reduction in silicon metal furnaces

Silicon is widely used as a raw material in various industries, including electrical industries, chemical industries, etc. in the production of industrial silicon metal, quartz (sio2) is used to provide silica, and carbonaceous materials (such as coal, pet coke, charcoal, and wood chips) are used to reduce silica. coal is used as a raw material in the production of silicon metal. in addition to acting as a reducer, coal reacts with sio gas as a carbon source in the furnace and prevents the release of sio gas by forming sic, or in other words, increases the efficiency of the furnace. coal also has a high electrical resistance due to its high percentage of volatile materials, which increases the furnace resistance and is effective in generating heat in the furnace. porosity and permeability are crucial in evaluating the effectiveness of coal as a reducing agent in silicon furnaces. the porosity and permeability of coal affect the rate of gas exchange during pyrolysis and contribute to the efficiency of reduction reactions. the higher the porosity and permeability of the coal, the better the volatiles are released; as a result, the higher the electrical resistance and furnace temperature, and the better the reduction. the mechanical strength of the coal affects its ability to withstand thermal stress during the silicon metal production process. as the temperature in the furnace increases, coal with lower mechanical strength may collapse or change its structure, hindering the overall reduction reaction. this change can reduce porosity and thus negatively affect permeability. in addition, the mechanical properties of the coal can also affect the packing density in the furnace. a denser packing with sufficient strength ensures minimal voids that can disrupt gas flow and ensures continuous and efficient reduction of silicon dioxide to silicon metal. coal is mainly composed of three maceral groups: vitrinite, liptinite, and inertinite. liptinites are usually hydrogen-rich and can contribute to the production of pyrolysis liquid. inertinite is composed of carbonized plant material and includes macerals such as fusinite and semi-fusinite. inertinite macerals are usually associated with higher carbon content and are often less reactive during combustion. certain types of organic matter (macerals) in coal affect its reactivity. inertinite macerals are less reactive than vitrinite or exinite. a higher proportion of reactive macerals (vitrinite, exinite) results in faster and more efficient reduction kinetics, improved silicon yield, and reduced energy consumption. the presence of significant amounts of inertinite can reduce process efficiency.