Evolution of Mg–Al-based Inclusions with Changes in Mg Content during Ladle Treatment Based on a Coupled Reaction Model

Abstract

In the steelmaking process, MgAl₂O₄ spinel inclusions diminish steel qualities and cause nozzle clogging based on the high melting point and low deformation of MgAl₂O₄. Typically, MgAl₂O₄ spinel inclusions are generated from Al₂O₃ inclusions with increasing MgO content, meaning ladle treatment does not represent an equilibrium state. However, complex reactions simultaneously occur between molten steel, slag, inclusions, refractory, and alloying elements during ladle treatment. Therefore, it is necessary to develop a kinetic model to predict compositional changes in molten steel, slag, and the inclusions during ladle treatment. Such a kinetic model must be able to simulate the generation of MgAl₂O₄ spinel inclusions from Al₂O₃ to control such inclusions. Additionally, MgAl₂O₄ spinel inclusions can evolve into MgO-rich inclusions with gradually increasing MgO content in Mg–Al-based inclusions. In this study, we developed an enhanced kinetic model based on a coupled reaction model with the compositional changes in Mg–Al-based inclusions. We also investigated the influence of the CaO/SiO₂ ratio in slag on the generation of spinel inclusions under industrial conditions for a 210-ton steel sample.