Mixed-Control Kinetic Model of Magnesia-Based Flux Dissolution in BOF Steelmaking Slags: Part 1 - Model Formulation and Validation With Literature Data

In basic oxygen furnace (BOF) steelmaking, it is very important to understand the dissolution mechanism of magnesia-based flux to improve the productivity of BOF vessels by increasing the refractory lining life and reducing the downtime of vessels. In the present study, a mixed-control kinetic model for the dissolution of calcined dolomite and calcined magnesite is presented. The model considers the formation of both dicalcium silicate (2CaO.SiO2 = C2S) solid solution on unreacted CaO and magnesiowüstite (MgO.FeO = MF') solid solution on unreacted MgO in the case of calcined dolomite, and only magnesiowüstite (MgO.FeO = MF') solid solution formation on MgO in the case of calcined magnesite. A general mixed-control kinetic model has been proposed taking the two diffusing components in BOF steelmaking slag as SiO2 and FeO (to estimate the dissolution rate of calcined dolomite) and only FeO (to estimate the dissolution rate of calcined magnesite); various slag compositions generally produced during BOF steelmaking are considered. The rate equation for mixed-control kinetics has been proposed and solved by using a computer program to find the dissolution rate. The predicted values of the dissolution rates are validated with experimental and operating plant data available in the literature, with encouraging results. Copyright Association for Iron & Steel Technology.