Silicon manganese alloy slag basicity

When smelting silico-manganese alloy, silicon and manganese are reduced from molten manganese silicate. MnO is easy to be reduced, while SiO2 is difficult to be reduced. In order to fully reduce the SiO2 to ensure the alloy composition, from the perspective of controlling the slag composition, low-basicity slag should be selected, and the lower the basicity, the better. However, when the alkalinity is lower than 0.5, the slag has a higher viscosity and is difficult to discharge from the furnace; and because of poor conductivity, it affects the uniform distribution of electric power in the furnace carrier, making it difficult to obtain a wide high temperature zone. As a result, SiO2 cannot be fully reduced, and the furnace conditions will deteriorate. An important factor affecting the basicity of slag is the reduction rate of SiO2. The way to increase the basicity of the slag is to increase the reduction rate of SiO2. It cannot be achieved by adding CaO or MgO, because the increase of CaO and MgO limits the reduction of SiO2 and reduces the recovery rate of Mn. Normally, it is appropriate to control the basicity of slag CaO/SiO2=0.5~0.7, CaO+MgO/SiO2=0.6~0.8. At this time, the content of SiO2 in the slag is 38~42%, and the content of MnO is about 10%.