The silicon manganese alloy produced by submerged arc furnace
Si-Mn alloy is an alloy composed of manganese, silicon, iron and a small amount of carbon and other elements. It is a kind of ferroalloy with wide application and large output. Si-Mn alloy is a compound deoxidizer commonly used in steelmaking, and it is also a reducing agent in the production of manganese metal by low carbon ferromanganese and electro-silicon thermal process. Si-Mn alloy can be smelted in large, medium and small carbon electrode paste ( closed paste) arc furnace by continuous operation.
Silicon and manganese distribution in the southwest of China is more, like Yunnan, Guizhou, Guangxi, Hunan. The raw materials of Si-Mn alloy produced by submerged arc furnace using carbon electrode paste include manganese ore, manganese – rich slag, silica, coke, etc.
The silicon and manganese in the silicon-manganese alloy have a strong affinity with oxygen. When the Si-Mn alloy is used in steelmaking, the deoxidizing products MnSiO3 and MnSiO4 melt at 1270℃ and 1327℃ respectively, which has the advantages of low melting point, large particles, easy to float up and good deoxidizing effect. Under the same conditions, the burning loss rates of manganese or silicon deoxidized alone are 46% and 37%, respectively, while the burning loss rates of Si-Mn alloy deoxidized alone are 29%. Therefore, it has been widely used in steelmaking. Its output growth rate is higher than the average growth rate of ferroalloy, and it has become an indispensable compound deoxidizer and alloy additive in iron and steel industry. The Si-Mn alloy containing less than 1.9% carbon is also used in the production of low carbon ferromanganese and electro-silicothermic process manganese’s semi-finished products. In ferroalloy production enterprises, the silicon manganese alloy used in steelmaking is usually called commercial silicon manganese alloy, the silicon manganese alloy used in low carbon iron smelting is called self-use silicon manganese alloy, and the silicon manganese alloy used in smelting metal is called high silicon silicon manganese alloy. MnSiO3, MnSiO and MnSiO3 can be formed by the combination of manganese and silicon. As can be seen from the state diagram of silicon and manganese, the most stable silicide is MnSi. Because of the negative value of the free energy of silicide formation of manganese, it is far greater than the negative value of the free energy of carbide production of manganese, the higher the silicon content in Si-Mn alloy, the lower the carbon content.
Si-Mn alloys are produced by submerged arc furnace which uses carbon electrode paste simultaneously reducing manganese ore (including manganese-rich slag) and manganese oxide and silicon dioxide with carbon.