Low iron spinel by aluminothermic fusion.

摘要

A spinel comprising from 20 to 40 and preferably 27 to 33 weight percent magnesium expressed as MgO, from 55 to 77 and preferably 63 to 69 weight percent aluminum expressed as Al2O3 from 2 to 4 weight percent titanium expressed as TiO2, less than 1 weight percent silicon expressed as SiO2, less than 0.5 weight percent iron expressed as Fe2O3 and less than 0.5 weight percent calcium expressed as CaO. The invention further comprises a method for the preparation of an aluminum-magnesium spinel containing less than 0.5 weight percent iron expressed as Fe2O3 which comprises fusing bauxite and magnesite together in the presence of metallic aluminum and separating the spinel from freed impurities. Preferably from 19 to 39 weight percent magnesite and from 56 to 76 weight percent bauxite and from about 1.5 to about 5 weight percent aluminum are used in the fusion and more preferably from 63 to 69 weight percent bauxite and from 27 to 33 weight percent magnesite and from about 2 to 4 weight percent metallic aluminum are used in the fusion.