Slag Properties in the Primary Production Process of Mn-Ferroalloys

Abstract

The thermodynamic and kinetic properties of the carbothermic reduction of MnO in the five-component slag, MnO-SiO2-CaO-MgO-Al2O3, is critical in the production process of Mn-ferroalloys. While the reduction rate is mainly dependent on the presence of a solid MnO phase in the slag for Mn-Fe-alloys, the rate for the Mn-Si-Fe alloys has two distinct steps, a slow step followed by a fast step. The extent of the slow step has been shown to be dependent on the S content in the slag. The thermo-physical properties of viscosity, density, interfacial tension and electrical resistivity is reviewed, and these properties are mainly determined by the total basicity.