What raw materials are used in smelting ferrosilicon manufacturers
When ferrosilicon manufacturers smelt ferrosilicon, the main raw materials used are silica, carbonaceous reducing agent and steel shavings. And in order to ensure the quality of ferrosilicon, there are strict requirements for raw materials. For example, silica is a rock made of quartz particles bonded by a binder, and the binder component is also SiO2. When ferrosilicon is smelted, all oxides except SiO2 are slag-forming substances. A large amount of slag in the furnace will result in poor furnace conditions. Therefore, the content of silica SiO2 used for smelting ferrosilicon is required to be greater than 97%, and the higher the better .
The impurities in silica are Al2O3, MgO, CaO, P2O5 and Fe2O3. Except Fe2O3, the rest are harmful impurities. About 80% of the phosphorus in silica is reduced into the alloy during the smelting process, so the content of P2O5 in silica should be less than 0.02%; Al2O3, MgO, and CaO are all slag-forming substances, and the reduced aluminum and calcium will pollute the alloy, so, The content of Al2O3 in silica shall not exceed 1%, and the sum of the contents of MgO and CaO shall not exceed 1%. Silica with poor anti-knock properties bursts into small pieces during the heating process, which affects the gas permeability of the charge. Therefore, silica with poor explosion resistance cannot be used for ferrosilicon smelting. The particle size of ore is an important process parameter for smelting. From the aspects of reaction speed, reaction contact area, and reaction uniformity, the particle size should be small, but in terms of the smooth discharge of CO gas and gas permeability, the particle size should not be too small. Therefore, the particle size of the silica entering the furnace should be appropriate. Generally speaking, the particle size of the silica entering the furnace is 30~100mm, and that of the small furnace is 25~60mm.
Most ferrosilicon smelting uses metallurgical coke as a reducing agent. In recent years, in order to increase the resistivity of electric furnaces and increase chemical activity, gas coal coke, silica coke, low-ash bituminous coal, blue carbon, semi-coke, low-temperature coke, wood chips or wood blocks have also been combined or used. In the chemical composition of carbonaceous reducing agents, fixed carbon, ash, volatile matter and moisture are mainly considered. The fixed carbon is high, the total amount of reducing agent required is reduced, so that the ash brings less impurities, the amount of slag is correspondingly reduced, the power consumption is reduced, and the impurity content in the alloy is reduced. The moisture is small and stable, which makes it easy to control the carbon ratio and stabilize the furnace condition. The resistivity of the carbonaceous reducing agent should be large, and the porosity should be high. Carbothermic smelting requires a large resistivity of the charge, and the resistivity of the charge mainly depends on the carbonaceous reducing agent. The higher the resistivity of the carbonaceous reducing agent, the deeper the electrode is inserted, the lower the heat loss at the furnace mouth, the larger the high-temperature reaction zone in the furnace, which makes the furnace conditions smooth and obtains good technical and economic indicators.
