Thermodynamic modelling of steelmaking slag to reduce refractory consumption during CONARC ® process

Abstract

CONARC^® steelmaking process which combines the basic oxygen and electric arc furnace steelmaking, requires precise operation and control of slag chemistry within an optimum range to reduce the refractory wear. The target slag should be MgO saturated, containing solid particles of magnesium wustite which ensures good foamy slag and causes less erosion of MgO-C refractory. In this present study, FactSage™ software was utilized to study and visualize the MgO saturation of slag through MgO-SiO₂-FeO-CaO-Al₂O₃-MnO and CaO-SiO₂-FeO-MgO-Al₂O₃-MnO systems. The ternary phase diagrams revealed, the slag was MgO-under saturated based on the current pattern of calcined lime and dolomite addition during the process. Based on the findings of this study, the addition pattern were altered to bring the slag regime within the MgO saturation level with good slag basicity. This change showed significant improvement in reducing the erosion rate of MgO-C lining in furnace and thereby reducing the specific gunning mass requirement.