A mathematical model for the reduction stage of the AOD process. Part II: Model validation and results

Abstract

A process model was proposed by Järvinen and co-authors for modelling the side-blowing decarburisation stage of the Argon-Oxygen Decarburisation (AOD) process. In Part I, a new mathematical model was derived for the reduction stage and coupled with the decarburisation model developed earlier. This paper, Part II, considers the validation of the model for the reduction stage with full-scale production data from a 150 t AOD converter in operation at Outokumpu Stainless Oy, Tornio Works, Finland. The results indicate that the model can accurately predict the end composition of the steel bath. Moreover, the model can be used to study rate phenomena during the reduction stage. Model predictions suggest that the reduction rate of chromium oxides is controlled initially by mass transfer of silicon onto the reaction surface and later by the diffusive mass transfer of chromium oxides in the slag droplets. Sensitivity of the model predictions to different initial bath temperatures, blowing times, ferrosilicon particle sizes and ferrosilicon feed rates was studied. © 2013 ISIJ.