Modeling of Chromium Oxide Separation to Liquid Slag and the Effect of Top Slag on Decarburization in an AOD Converter

摘要

The AOD (Argon-Oxygen Decarburization) converter is a common reactor for refining stainless steel grades. The process has high productivity and yields good reduction of carbon and sulfur with small chromium losses. Since stainless steel have high demands on alloying elements as well as keeping losses to a minimum, these parts need to be studied further. A high-temperature thermodynamics model has been coupled with a CFD (Computational Fluid Dynamics) model describing the fluid flow. The boundary conditions were chosen based on data for an industrial AOD converter and they have been reported in literature earlier. With this model, separation of chromium oxide to liquid slag and the effect of the top slag amount during decarburization have been investigated. The liquid slag was considered for the uptake of chromium oxide, while the top slag was only considered for its contribution to increase the metallostatic pressure. The results suggest that separation of chromium oxide to liquid slag inhibits the decarburization. The same conclusion can be drawn with respect to the amount of solid top slag. However, the effects are rather small so they do not affect the process noteworthy. Overall, it is concluded that the impact of the top slag and liquid slag on the reactions should be investigated further.