Ferrosilicon manufacturers in smelting ferrosilicon, the main use of raw materials are silica, carbon reducing agent and steel chips. And in order to ensure the quality of ferrosilicon, there are strict requirements for raw materials. Silica, for example, is a rock made of quartz particles held together by an adhesive, also made of SiO2. When smelting ferrosilicon, except for SiO2, the other oxides are slagging materials, and the slag quantity in the furnace is poor. Therefore, the silica SiO2 content required for smelting ferrosilicon should be greater than 97%, and the higher the better.
Impurities in silica include Al2O3, MgO, CaO, P2O5 and Fe2O3. Except Fe2O3, the rest are harmful impurities. About 80% of phosphorus in silica is reduced into the alloy in the smelting process, so the content of P2O5 in silica should be less than 0.02%; Al2O3, MgO and CaO are slagging materials, and reduced aluminum and calcium will pollute the alloy, so the content of Al2O3 in silica shall not be more than 1%, and the sum of the content of MgO and CaO shall not be more than 1%. The silica with poor blast resistance is broken into small pieces during the heating process, thus affecting the permeability of the charge. Therefore, silica with poor knock resistance cannot be used in ferrosilicon smelting. The particle size of ore is an important process parameter of smelting. From the perspective of reaction speed, reaction contact area and reaction uniformity, the particle size should be small, but from the perspective of smooth discharge of CO gas and permeability, the particle size should not be too small. Therefore, the size of silica into the furnace should be appropriate. In general, the size of silica into the furnace of large electric furnace is 30~100mm, and that of small electric furnace is 25~60mm.
Smelting ferrosilicon mostly uses metallurgical coke as reducing agent. In recent years, in order to increase the resistivity of electric furnace and increase the chemical activity, there are also collocation or use of gas coal coke, silica coke, low ash bituminous coal, blue carbon, semi-coke, low temperature coke, wood chips or wood blocks. In the chemical composition of carbonaceous reductants, fixed carbon, ash, volatile matter and water are mainly considered. The fixed carbon is high, the total amount of reducing agent is reduced, so the ash brings in less impurities, the slag amount is reduced correspondingly, the power consumption is reduced, and the impurity content in the alloy is reduced. Small and stable moisture, easy to grasp the carbon ratio, stable furnace condition. The resistivity and porosity of carbonaceous reducing agent should be high. Carbonthermal smelting requires high resistivity of charge, which mainly depends on carbonaceous reducing agent. The higher the resistivity of carbon reducing agent is, the deeper the electrode is inserted, the lower the heat loss of furnace mouth and the larger the high temperature reaction zone in furnace make the furnace condition smooth and obtain good technical and economic indexes.
