Slag resistances of alumina-spinel castables containing different types of spinel were investigated using the static crucible test. The corroded samples were characterized using an X-ray diffractometer, a scanning electron microscope, microscopic measurement method etc. Based on the results, the effects of light-burned spinel and commercial fused spinel on the slag resistance of the castables were discussed and compared. It has been found that light-burned spinels could improve the slag penetration resistance of alumina-spinel castable more efficiently than their fused counterparts, if their chemical composition, particle size, lattice distortion extent and grain size are properly controlled. The light-burned spinel containing 70 wt% Al2O3 has greater lattice distortion and smaller particle size, making the penetrated slag more viscous and resulting in smaller pore sizes in the matrix. On the other hand, its smaller grain size only results in a slightly higher dissolution rate. Therefore, compared with the fused spinel containing the same amount of Al2O3, it could greatly enhance the slag penetration resistance of the castable while only slightly negatively affecting the corrosion resistance.

Keywords: Alumina-spinel castables; Light-burned spinel; Fused spinel; Slag; Corrosion mechanism