A Study of Commercial Magnesia-Alumina Spinels for Alumina-Spinel Castables

摘要

The lattice constants and corresponding alumina contents of MgO·Al_2O_3 spinels, as estimated from the lattice constants, have been compiled from actual observations on eight commercial spinels. A considerable discrepancy has been observed between the alumina content estimated from the lattice constant and that given in specification of the calcined spinel containing 94 mass-% Al_2O_3 and the electrofused spinel containing 88 mass-% Al_2O_3. However, the alumina contents of the other two samples of calcined spinels containing 89-90 mass-% and 73 mass-% Al_2O_3 as given in the specification are very close to those estimated from their lattice constants. The slag test reveals that the penetration resistance of alumina-spinel castables slightly decreases while the erosion resistance of the castables slightly increases with increase in alumina content of the spinel, as estimated from its lattice constant. The optimum alumina content of the spinel has been observed to be around 85 mass-%, and the wear resistance of the castables made by using same amounts of spinels containing 89-90 mass-% and 94 mass-% Al_2O_3, is very close.