Speaker
Description
In basic oxygen steelmaking, the metal droplet decarburization plays a major role to determine the residence time and reaction (slag/metal interfacial) area of the droplets due to bloating while reacting in the emulsion zone. This ‘residence time’ and ‘reaction area’ controls the overall refining efficiency in BOF, more importantly dephosphorization efficiency. So, it is important to understand the mechanism of decarburization reaction to predict the bloating behavior accurately. In this study, an experimental study has been performed to understand the effect of slag conductivity on the decarburization reaction kinetics. A kinetic model based on Wagner’s oxidation theory has been proposed and a kinetic analysis has been performed to explain the slag conductivity effect. It has been observed from study of decarburization on varying carbon content from 0.5% to 4.4% in oxidizing slag, that the droplet decarburization always shuts down in low conductivity slag much earlier than that predicted by the thermodynamics. It is proposed that during the decarburization process, due to the difference in diffusivities of ions and difference in the rate of cathodic and anodic reactions, there is a charge build up at the slag metal interface. This introduces an electric field which opposes the movement of oxygen ions towards slag-metal interface and this is attributed to the sudden shutdown of decarburization process for metal droplets on low conductivity slags whereas to continue decarburization until close to equilibrium in high conductivity slag due to fast charge dissipation.