An improved process for the production of low carbon ferromanganese

Low carbon ferromanganese (LC-FeMn) is an essential ingredient for making high strength low alloy steel and stainless steel. The conventional industrial scale silicothermic method for the production of LC-FeMn comprises several energy intensive complex steps consuming about 2000 kWh/ton. We have attempted an improved silicothermic process, which is based on a single step smelting of optimized charge mix in the electric arc furnace (EAF). Thermochemical simulation of the smelting process by FactSage 6.4 showed significant effect of the charge mix basicity (B=CaO/SiO2) on manganese, iron, silicon and phosphorous distribution between the metal and slag. The optimum basicity was found to be 1.5 at the charge mix ratio i.e., Mn ore: Lime: SiMn of 1:1:0.6 in the smelting tests. Under optimum conditions, the energy consumption was about 690 kWh/ton. This approach has potential benefits for the ferromanganese industry in terms of simpler and energy efficient process.