The production and uses of manganese silicon alloy

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Manganese-silicon alloy is a kind of alloy composed of manganese, silicon, iron and small amount of carbon and other elements. It’s a widely-used and productive ferroalloy. It’s consumption is ranked the second in electric furnace ferroalloy products. The manganese and silicon in it has strong affinity for oxygen, using manganese-silicon alloy in steelmaking would produce the deoxy products MnSiO3 and Mn2SiO4 (the melting point are 1270℃ and 1327℃ respectively)which have the advantages of low melting point, large particle , easy to float and good deoxidation effect, etc. Under the same conditions, using manganese or silicon to deoxidize alone, the damage rates are 46% and 37% ,while the damage rate is 29% when using manganese-silicon alloy. Therefore, it is widely used in steelmaking, the growth rate of it’s output is higher than the average growth rate of ferroalloy’s and even higher than that of the steel’s, has become the indispensable compound deoxidizer and alloy additive in steel industry. For manganese silicon alloy which carbon content is less than 1.9% can be used as semi-products in producing medium and low carbon ferromanganese and electro silicothermic manganese metal.

In ferroalloy production industry, usually called the steel-making manganese-silicon alloy as commercial manganese-silicon alloy, the medium and low-carbon ferromanganese-making ones as manganese silicon alloy, the metal manganese powder-making ones as high silicon ferromanganese-silicon alloy. Manganese and silicon can form silicides like MnSi2, MnSi and Mn5Si3. The most stable one is MnSi. In manganese silicon alloy, the higher silicon content, the lower carbon content.

In the smelting of manganese-silicon alloy, in order to make the slag discharged smoothly and improve the recovery rate of the manganese powder, it needs to be added dolomite or lime and other flux in the furnace charge to maintain the slag’s suitable alkalinity n (CaO + MgO) / n (- SiO2). Manganese silicon alloy is smelt in weak acid residue, if the alkaline oxide’s content is too low in the slag, then the conductivity of slag and furnace power will be unevenly distributed, the slag, moreover, will be viscous with poor fluidity, the furnace conditions will be worse; if appropriately increase CaO and MgO, improve slag’s conductivity, the temperature in the furnace  will be raised, for which the slag’s viscosity is reduced, improving the fluidity of the slag, making the slag easily discharged, expanding the melting crucible.

Some metal powder manufacturers use manganese slag or the carbon manganese slag (the by-products slag while producing carbon ferromanganese or high carbon ferromanganese) to replace part of the flux to add in the manganese silicon alloy charge, which also plays a role in adjusting the slag’s alkalinity; due to the strong m (Mn) / m (Fe) and m (Mn) / m (P) of manganese slag and carbon-manganese slag, the mixture’s m(Mn)/m(Fe) and m(Mn)/ m (P) are correspondingly increased after the charge is added, which not only reduced the intake of flux and silica but also increased the grade rate of manganese silicon alloy and comprehensive recovery rate of manganese.

The production of manganese silicon alloy and high carbon ferromanganese has the same requirments. All the furnace raw materials must comply with the stipulated size requirements, the water content should as low as possible. The smelting of manganese silicon alloy can adopt continuous operation method in large, medium and small-sized ore heat furnace. In addition to the generally using the process measures of sedation and bottom burning, the smelting process of own-used manganese silicon alloy has no other differences with commodity manganese silicon alloy; In the production of high silicon manganese alloy, the iron as impurities is strictly controlled, it’s production process has significant differences with ordinary manganese silicon alloy. Currently, manganese silicon alloy electric furnace is developing towards the direction of large-scale, totally enclosed.