Research on improving manganese ore yield in converter based on the less-slag smelting process

To further explore the reaction mechanisms of direct alloying using manganese ore and the factors influencing manganese ore yield in converter, this study re-established a thermodynamic reaction model for direct alloying with manganese ore by coupling the oxidation and reduction reactions of [Mn]. The model investigated the equilibrium relationships between (MnO) content in slag, (FeO) content, temperature, and manganese content under different carbon levels. Through thermodynamic calculations, it is concluded that: endpoint [C] content greater than 0.13%, (MnO) content in slag greater than 20%, (FeO) content between 9% and 15%, and endpoint temperature above 1620 °C, which can achieve [Mn] content in molten steel over 0.5%. Through hot-state experiments in a 500 kg medium-frequency induction furnace, achieving a manganese ore yield of 38.7–48.4% under laboratory experimental conditions. By using the double-slag process to improve the dephosphorization rate in the primary stage, less-slag control in the later stage and high-carbon tapping are achieved. By adding 5.5–10.5 kg/t of manganese ore during the decarburization period, a higher manganese ore yield of exceeding 50% is achieved, with carbon content at the endpoint reaching 0.16–0.22% and slag volume controlled between 40 and 60 kg/t.