Role of spinel composition in the slag resistance of Al2O3–spinel and Al2O3–MgO castables

Abstract The slag resistance of Al 2 O 3 –spinel, Al 2 O 3 –MgO and high-Al 2 O 3 castables was tested using a gas-fired rotary slag test furnace and BOF slag (CaO/SiO 2 =3.8, Fe 2 O 3 =33.4 wt.%). The spinels used in the test contained 73, 90 and 94 wt.% Al 2 O 3 . The XRD patterns showed that no spinels can be identified in the mixes consisting of 75 wt.% BOF slag +25 wt.% spinel and being fired up to 1400° or 1500 °C. The same mixes were used for a sessile drop test using a prefired Al 2 O 3 –spinel castable as a substrate. The experimental results indicated that the penetration decreases with the increasing MgO content in spinels. The role of spinel composition in the slag resistance of Al 2 O 3 –spinel and Al 2 O 3 –MgO castables is to dissolve itself in the penetrating slag and as a result to lessen the penetration.