Ferrosilicon Refining methods outside the furnace

Refining outside the furnace

Electrical steel requires ferrosilicon with higher purity. Some elements such as Ti and Mn need to be made of pure raw materials to meet the requirements. The Al, Ca, C and other elements in the product are solved by refining outside the furnace. There are three types of ferrosilicon refining methods outside the furnace: slag refining, oxygen refining and chlorine volatilization.

1. Slag refining method: quartz, limestone and dolomite are melted in an electric furnace to obtain synthetic slag. The ferrosilicon and slag are mixed in a ladle, and after repeated pouring from the furnace to the ladle for several times, ferrosilicon containing Al <0.01% can be obtained. Refining 1t of ferrosilicon consumes 2000~2500kWh of electricity. Use synthetic slag containing 45%~55% SiO2, 25%~30% CaO, 10%~13% CaF2, 8%~10% FeO, and the amount is 13%~17% of the weight of ferrosilicon.
2. Oxygen refining method: oxygen is blown into the molten ferrosilicon from the porous plug at the bottom of the ladle, and slag is added to the surface of the ferrosilicon.
3. Chlorine volatilization method: chlorine is blown into the ferrosilicon melt to volatilize Al and Ca into chlorides. This method is no longer used due to serious environmental pollution.