Ferro-silicon alloy 70# and industrial silicon belong to silicon-based alloys in the ferroalloy industry, and are widely used in steelmaking, casting, non-ferrous metals and other industrial production. The production of 70 ferrosilicon alloy and industrial silicon uses silica as raw material. After washing with water, it is mixed with carbonaceous reducing agent and added to submerged arc furnace. Under high temperature conditions, ferrosilicon alloy and metal silicon are obtained by carbothermal reduction.
In the production of 70 ferrosilicon alloy and industrial silicon, in order to ensure the gas permeability of the charge, the charge is required to be within a certain particle size range. During the cleaning process of silicon ore, the silicon ore with a particle size of <20 will be screened to avoid entering the submerged arc furnace and affecting the gas permeability of the charge. Due to the lack of effective utilization channels, this part of silicon ore with a particle size of <20 is usually discarded and stockpiled, resulting in a waste of silicon ore resources, and at the same time increasing the production cost of 70 ferrosilicon alloy and industrial silicon.
The flue gas produced in the production process of 70 ferrosilicon alloy and industrial silicon is rich in a large amount of silicon dioxide micropowder, and after being collected by dust removal equipment, the microsilica powder with a silicon dioxide content of 80.5% can be obtained. Every 5t of ferrosilicon produced by China’s ferroalloy factories will produce It microsilica; every 3t of industrial silicon produced will produce It microsilica. According to statistics, the output of ferrosilicon in China in 2012 was 4.78 million tons, and the output of industrial silicon was 1.13 million tons. Correspondingly, in 2012 alone, China will produce 1.33 million tons of silica fume. At present, micro-silica fume is mainly used as an additive in concrete, refractory materials and other fields, with a small amount of use and low economic value. As a result, the sale of micro-silica powder is not smooth, and a large amount of it is piled up in the factory area, which not only occupies the area of the production area, but also brings pollution to the surrounding environment.
At present, there is no good way to utilize the small particle size silicon ore (particle size <20mm) and microsilica produced in the production process of 70 ferrosilicon alloy and industrial silicon. A large amount of small-sized silicon ore and micro-silica powder are piled up in the factory area, which not only causes waste of silicon ore resources and reduces the economic benefits of the factory, but also occupies a large area of the production area and brings pollution to the surrounding environment of the factory area. Threat to the healthy development of enterprises. How to effectively utilize small particle size silicon ore and microsilica has become an urgent problem to be solved in the ferroalloy industry.