Phase Transitions and Reaction Mechanism of Ilmenite Oxidation

The oxidation of ilmenite ore is used in titanium processing. The effects of oxidation conditions, namely, temperature, ilmenite particle size, and oxygen pressure, on the product phase were investigated. The oxidation product from 773 to 1073 K (500 to 800 A degrees C) includes a shear structure phase (Fe2Ti3O9, named H239), rutile, and hematite, while pseudobrookite is the only stable phase above 1073 K (800 A degrees C). The particle size of the ilmenite ore is the most important factor that determines the crystalline phase composition of the product. A small particle size enhances the formation of H239. High oxygen pressure also favors the formation of H239, while the temperature is a less important factor. Similar experiments showed that these trends also hold for the oxidation of pure ilmenite. The oxidation mechanism is discussed. The oxidation kinetics is well described by a parabolic law.