Reduction of MnO from molten slags with liquid steel of high carbon content

This work estimated the reduction of MnO in slags of the CaO-SiO₂-FeO-CaF₂-MnO system and liquid steel with the initial composition (mass contents) 0.75% Mn, 0.16% Si and 0.5 to 2.0% C, as an alternative to introducing Mn to the steel melt. The slag basicities (CaO/SiO₂) in the experiments were 2 and 3. MnO was obtained from manganese ore. The experiments were carried out in an open 10 kg induction furnace using Al₂O₃-based refractory at 1873 K. The oxygen potential was measured throughout the experiments with a galvanic cell (ZrO₂-solid electrolyte with a Cr/Cr₂O₃ reference electrode). The MnO reaction mechanism was analysed in terms of the slag basicity, the silicon and the initial carbon contents in the melt. The rate and the degree of MnO reduction were found to increase with the increasing of initial carbon content; however, the effect of slag basicity was less important. A kinetic analysis of the process was performed using a coupled reaction model.