<p>The prediction of early slag formation and hot metal refining in the oxygen steelmaking is critical to the progress of the blow and consistently achieving the target end-point metal composition. In the current study, a heterogeneous reaction kinetic model based on the unreacted shrinking core model was developed to predict the formation of oxides and the refining rates of elements within the droplet splashed in the cavity zone. The present model takes into account the shrinkage of the unreacted core and the growth of oxide layer. The results show that the oxidation of droplet can be divided into two stages: an initial linear rate of oxidation, followed by a parabolic rate of oxidation. A detailed sensitive analysis was conducted in this study, which suggests that the kinetics of oxide formation is controlled by the counter diffusion of FeO and Fe₂O₃ through the oxide layer. The influence of dynamic process conditions on the formation of oxide layer and the refining rates of carbon, silicon and manganese were also investigated. Finally, incorporating the submodules from McMaster’s global BOF decarburization model, the current kinetic model was validated by the plant trial results reported in the open literature.</p>