BrownFusedAlumina

The electrothermal fusion of bauxite at 2100°C yields an impure and brown electrofused alumina product called brown fused alumina, sometimes simply brown corundum. Brown fused alumina exhibits coarse grains, and the major impurity in brown fused alumina is titania or titanium dioxide (TiO₂) coming from the bauxite ore. Therefore, commercially, two grades of brown fused aluminas can be distinguished according to their titania content: the friable grade, with 1.5 wt.% TiO₂, and the standard grade, with 3 wt.% TiO2 , which exhibits a greater toughness than the friable grade.

Brown electrofused alumina is obtained industrially by the simultaneous electrothermal fusion and reduction by coke in a tilting and triphased electric-arc furnace of a blend of bauxite and spent products of white and brown aluminas.