Application of 28 GHz Microwave Irradiation to Oxidation of Ilmenite Ore for New Rutile Extraction Process

Abstract

Microwave heating has been applied to the oxidation in the new rutile extraction process developed by the authors in which rutile is extracted from a natural ilmenite ore by oxidation and magnetic separation followed by leaching with diluted acid. Since ilmenite FeTiO₃ and pseudobrookite Fe₂TiO₅ strongly absorb 28 GHz microwave, Australian ilmenite ore mainly composed of FeTiO₃ was rapidly heated up to about 1 273 K and oxidized in air with keeping almost constant temperature. As a result, two equilibrium phases of rutile TiO₂ and pseudobrookite were quickly formed at microwave power of 1.5 kW. The growth rate of the pseudobrookite phase in the microwave irradiation was found to be much faster than that of the rutile phase in the conventional resistance furnace, indicating a drastic enhancement of the growth rate by the microwave irradiation.