Perovskite Formation in Hematite–Ilmenite Ores Sintered in Argon

Abstract

In the sintering of Ti-containing iron ores, the formation of perovskite was reported to harmfully affect the formation of silico-ferrite of calcium and aluminum. The formation of perovskite in ore blend of hematite and ilmenite ores in an Ar atmosphere was investigated in the temperature range of 1373 to 1523 K employing high-temperature in situ X-ray diffraction. The temperatures of melt formation in the ore blends were estimated employing thermal analysis in terms of thermogravimetric-differential scanning calorimetry. The hematite ore was thermally decomposed to magnetite at high temperatures accompanied by the release of oxygen combined with iron. Addition of ilmenite ore to hematite ore increased the temperature of melt formation in the sintering of the ore blend. Ilmenite, FeO center dot TiO2(s), in the ore was oxidized to a metastable phase of Fe2O3 center dot 2TiO(2)(s) and was acerbated by oxygen released from thermal decomposition of hematite at about 1423 K. Then the Fe2O3 center dot 2TiO(2)(s) decomposed to release TiO2(s) which reacted with CaO(s) to form perovskite-containing compound, CaO center dot TiO2 center dot SiO2(s). MgO(s) interfered with the release of TiO2(s) by forming some stable or metastable magnesium titanium oxides such as Mg0.6Fe0.4O center dot Fe0.2Ti1.8O3(s), Mg0.9Ti0.1O center dot 2TiO(2)(s), MgO center dot Fe2O3 center dot 3TiO(2)(s), MgO center dot 2TiO(2)(s), and MgO center dot TiO2 center dot Mg0.2Ti0.8O2(s) during the sintering of the hematite-ilmenite ore sinter blend. These compounds might have some potential of decreasing the available amounts of free TiO2 for formation of CaO center dot TiO2 center dot SiO2(s) in this system.