A Dynamic Mixed-Control Model for BOF Metal–Slag–Gas Reactions

Basic oxygen steelmaking has been the interest of research for several decades due to its complex and fast process dynamics. To predict the evolution of slag–metal composition and temperature, it is important to control the process efficiently. The framework developed by Sarkar et al. (Metall Mater Trans B 46:961–976, 2015) is advanced further to estimate the evolution of chemical composition and temperature of molten metal and slag. In this present study, a period of flight is considered for droplets at the early period of blow when stable emulsion has not formed. The size distribution of the droplets is evaluated according to the Rosin–Rammler–Sperling distribution. A coupled mixed-controlled kinetic model is incorporated in order to quantify the extent of reaction at the interface of a single droplet in the emulsion phase. This kinetic model assumes that transport of species in both metal and slag phases are rate controlling. Reaction kinetics of these individual droplets are tracked at each time step throughout its period of residence in the metal–slag–gas emulsion, to predict the evolution of the metal and slag compositions for the entire converter with blowing time. Evolution of the bath temperature is estimated by developing a thermal model. The predictions from the model, when validated with plant trial data, could efficiently simulate the phosphorus and manganese reversal phenomena, along with the early removal of silicon (Cicutti et al. in 6th International Conference on Molten Slags, Fluxes and Salts, Stockholm-Helsinki, 2000, Paper 367, pp. 1–9, 2000).