High temperature carbothermic reduction of Fe2O3–TiO2–MxOy oxide mixtures

Metal–slag phase compositions of molten iron metal and high titania slags or solid titanate phases were determined between 1500 and 1700 °C. In particular the influence of so-called ‘impurity oxide’ (MnO, MgO, Cr2O3, Al2O3 and SiO2) additions, gas atmosphere, temperature and amount of reductant was investigated. Under strong reducing conditions iron oxide was almost completely reduced and the slag phase solidified as a consequence thereof because FeO acts as a fluxing agent for high titania slags. Cr2O3, SiO2, MnO were also reduced to a high degree. Under weak reducing conditions a fully molten slag was stable as iron oxide was only partially reduced. A large portion of manganese and some magnesia, were removed via the gas phase due to their considerable vapor pressures. Alumina was not reduced under the applied conditions. Continued reduction is easily achieved but resulted in titania slags with over 90 wt.% TiO2 with liquidus temperatures above 1700 °C. A comparison of the experimental results with industrial data suggests that industrial ilmenite smelting process operate under non-equilibrium conditions.