Silica, carbon reductant and iron raw materials are weighed according to the number of ingredients, mixed and added into the furnace. Large - scale electric furnace to feed the main tube feeding, furnace feeder feeding machine for auxiliary. The operation procedure is: after discharging the alloy, lower the electrode and electrify; When the current reaches the specified value and becomes stable, the furnace is rammed with a ramming machine to destroy the remaining sticky crust around the electrode on the furnace and push it to the center of the furnace, and then new material is stamped. The normal mark of ferrosilicon smelting is that the electrode position is stable and deeply inserted in the charge. The electrode current is kept at the specified value, and the power supply load is stable. Uniform fire on the material surface, no dead material area, no "piercing fire"; The material layer is soft and sinks uniformly around the electrode. Smelting crucible large; Easy opening of iron outlet; Large iron flow, stable iron output and slag discharge. During smelting, when a certain amount of ferrosilicon is stored at the bottom of the furnace, the specified smelting time shall be taken out. When 75% Si ferrosilicon is smelted in electric furnace above 10000kVA, it is produced 4 ~ 5 times every 8 hours; Smelting 45% Si ferrosilicon, 5 ~ 6 times every 8 hours. Ferrosilicon fluid flows into the molten metal. To the ingot room, after sedation and removing the surface of the furnace slag, poured into the ingot mold or ingot casting machine. To avoid segregation of ferrosilicon components, the thickness of FeSi75 ingot is <100mm, and the thickness of FeSi45 ingot is <150mm. To maintain normal furnace conditions and good technical and economic indicators, (1) the ratio of SiO2 and C should be accurately controlled. A large amount of SiO(gas) will be produced in smelting process due to insufficient carbon allocation. Part of silica melts into slag, making crucible smaller and smelting situation worse; The electrode position is unstable, the material surface becomes dead, and "stabbing fire" is serious; Silicon recovery decreased; The power consumption increases. On the contrary, if the carbon content is excessive, then the charge resistance becomes smaller; SiC is produced more often and suspended in liquid alloy and slag phase, which improves the melt viscosity. Smelting crucible smaller; Difficulty in alloy discharge; At the same time, the electrode insertion charge is shallow, the charge surface "piercing fire" is serious. The relationship between the carbon content of FeSi75 and the silicon recovery is shown in Figure 5. (2) Use a reductant with higher resistance and better reactivity. The relationship between the reactivity of carbon reducing agent and the smelting power consumption of FeSi75 is shown in Figure 6. (3) Appropriate electric furnace geometry structure and smelting power supply parameters, reasonable charge size is also important for smelting.
