Non-isothermal reduction kinetics during vacuum carbothermal reduction of ilmenite concentrate

摘要

The non-isothermal reduction kinetics and mechanism during the vacuum carbothermal reduction of ilmenite concentrate were investigated by X-ray diffraction, backscattered electron imaging, energy-dispersive X-ray spectroscopy and FactSage 7.2 at temperatures ranging from 1000 degrees C to 1400 degrees C. The quick reduction reaction appeared at 1200 degrees C-1300 degrees C and slowed down after 1300 degrees C. At 1200 degrees C, magnesium was dispersed throughout the sample, and silicon, calcium, and aluminum were dispersed and distributed in the same region. At 1350 degrees C, magnesium began to gather and show the same distribution as those of silicon, calcium, and aluminum. The reduction process was mainly FeTiO3 - FeTi2O5 - Ti3O5 - Ti2O3. During the reduction process, the iron continued to nucleation, aggregate and grow, and the high-valence titanium was reduced to low-valence titanium and gradually enriched. Comprehensive consideration of Satava-Sestak method and Coats-Redfern method, the apparent activation energy of the reduction process was 233.16 +/- 8.40 kJ/mol.