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

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 of the following reactions was calculated to be -184.7, -196.0 kj·mol^-1 at 1373 K, respectively. Fe(s)+FeTiO₃(s)+1/2O₂(g)=Fe₂TiO₄(s) Fe(s)+TiO₂(s)+1/2O₂(g)="FeTiO₃"(s) Both the activities of magnetite and ulvöspinel in the Fe₂TiO₄-Fe₃O₄ spinel solid solutions coexisting with metallic iron at 1373 K obtained exhibit negative deviations from Raoult's law.