Author:

Abstract:

Industrial tests were performed to investigate the reduction behaviour of chromium oxide and its correlation with slag foaming during electric arc furnace (EAF) stainless steel refining. From a thermodynamic point of view, the chromium recovery is improved by increasing (1) the slag basicity, (2) the Al2O3 level in the slag and (3) the dissolved silicon content in the steel. Kinetic conditions influence the chromium recovery as well. Chromium oxide reduction predominantly occurs during tapping, owing to the intimate mixing of steel and slag. During the EAF reduction stage some chromium recovery also takes place which is correlated with the foaming degree during the preceding carbon/oxygen blowing stage. Foaming behaviour requires a moderate effective slag viscosity and sufficient gas generation. This can be controlled by targeting a multitude of small second phase MgO. (Cr,Al)2O 3 spinel precipitates in a basic slag. By optimising the chromium oxide content in the initial slag and the slag basicity evolution during the EAF process, it is thus feasable to concurrently achieve a sound slag foamy practice and a high chromium recovery.