Reaction behavior of slag and spinel in steel ladle castables

Abstract

The difference in corrosion behavior between alumina-spinel and alumina-magnesia castables in a steel slag was investigated with emphasis on the composition of spinel phase. The spinel primarily-added to the alumina-spinel castable had the stoichiometric composition, whereas the spinel forming secondarily in the alumina-magnesia castable was in an alumina-rich composition. The model reaction between sintered spinel and slag revealed that the stoichiometric spinel was highly wettable to slag and the molten slag deeply penetrated into the sintered body. In contrast, the alumina-rich spinel was less wettable. It was found that the alumina-rich spinel changed into stoichiometric one at the interface between spinel and slag, and that an iron-alumina spinel formed following to dissolution of the excessive alumina into slag. The increase in alumina content seemed to increase the viscosity of the slag, leading to retardation of penetrative wetting of slag to the alumina-rich spinel.