Phase relations and equilibrium oxygen partial pressures in iron-titanium-oxygen system at 1373 K

Abstract

Phase relations and the equilibrium oxygen partial pressures in the Fe-Ti-O ternary system at 1373 K have been studied using a thermogravimetric technique in various atmospheres buffered by a CO-CO2 gas mixture and X-ray diffraction technique. The results indicate that at 1373 K ilmenite (FeTiO3) can be reduced and decomposed to iron and rutile (TiO2). Consequently upgrading ilmenite to a rutile substitute is possible in principle. From the present results, the standard Gibbs energy change of the reactions in the temperature range of 1173-1373 K were obtained as follows: Fe(s)+FeTiO3(s)+1/2O2(g)=Fe2TiO4(s), ΔGro/J·mol-1(Fe 2TiO4)=-271600+63.35T/K±100, Fe(s)+TiO2(s)+1/2O2(g)=FeTiO3(s), ΔGro/J·mol-1(FeTiO 3)=-282400+62.93T/K±100. Both the activities of magnetite and ulvospinel in the Fe2TiO4-Fe3O4 spinel solid solutions coexisting with metallic iron at 1373 K obtained exhibit negative deviations from Raoult's low.