Microstructure and Chemical Transformation of Natural Ilmenite during Isothermal Roasting Process in Air Atmosphere.

Ilmenite is a vital raw material for the production of metal titanium and titanium-containing materials. In this paper, microstructure and chemical transformation of natural ilmenite in air atmosphere were investigated by the analysis of XRF, X-ray diffractometer, and SEM-EDS. Results showed that the untreated ilmenite had three layers after oxidation at 800 °C for 60 min, which were Fe₂O₃, TiO₂ and the inside mixture layer of Fe₂O₃ and TiO₂ in turn. Subsequently, it was roasted at 900 °C, and Fe₂Ti₃O₉ was firstly developed between Fe₂O₃ and TiO₂ layers. With the increase in the roasting time, the Fe₂Ti₃O₉ layer was decomposed into Fe₂TiO₅ and TiO₂, and Fe₂Ti₃O₉ continued to be formed along the diameter direction toward the center of the particle until Fe₂TiO₅ and TiO₂ were formed as the final products in the center of particles. Pseudorutile in natural ilmenite was directly decomposed into TiO₂ and Fe₂O₃ in the roasting process. [ABSTRACT FROM AUTHOR]