A comparative study on refractory wear associated with fluxes for AOD slags

Abstract

Argon-oxygen decarburisation (AOD) is the most common process for refining stainless steel. The AOD slag becomes highly viscous during the decarburisation stage. To promote efficient reduction of slag and desulphurisation, fluxes are added to reduce the viscosity of the top slag. The objective of this work was to compare a synthetic fluorine-based flux to fluorspar (CaF2) from the perspective of refractory wear. For this purpose, high temperature experiments were carried out using crucibles which were prepared from fired doloma bricks and filled with a mixture of synthetic slag and flux. To provide a theoretical point of comparison, computational thermodynamics calculations were performed to compare the melting point of the slag. The results of the calculations suggest that the synthetic flux is more effective than fluorspar in lowering the melting point of the slag. It was estimated that the performance of the current process practice can be obtained with approximately 20% less flux if fluorspar is substituted by the synthetic flux.