An Innovative Technology for Utilization of Oolitic Hematite via Microwave Fluidization Roasting: Phase, Structure and Reaction Kinetics Analyses

ABSTRACT

Oolitic hematite, as a complex and refractory iron ore resource, can be efficiently utilized by magnetic roasting. In this study, to ascertain the mechanism of microwave fluidization roasting technology (MFR) for the utilization of oolitic hematite, the influence of MFR on mineral magnetism, ore microstructure, mineral phase and kinetics was further explored and clarified. The results show that under the optimized conditions of the roasting temperature 650°C for 5 min, CO concentration 30%, and ore fineness with −74 μm accounting for 90%, the saturation magnetization and saturation susceptibility of the roasted product reached the maximum respectively. Microstructure analysis shows that microcracks were generated between iron minerals and gangue minerals and gradually extended to the core of the oolitic structure with a prolongation in pretreatment time, which was particularly propitious to upgrade the iron minerals in the subsequent grinding and magnetic separation process. The isothermal kinetics shows that the apparent activation energy and pre-exponential factor of kinetic parameters in MFR process decreased gradually with a decrease in ore particle size, and the mechanism function for ore with the particle of −0.15 mm was in accordance with the one-dimensional diffusion model k = 3.805exp(−24075/RT).

KEYWORDS:

• Microwave fluidization roasting
• phase and magnetism transformation
• microstructure change
• kinetics mechanism

Acknowledgments

The authors would like to thank the National Natural Science Foundation of China (Grant No.51874071, 51734005), the Fok Ying Tung Education Foundation for Yong Teachers in the Higher Education Institutions of China (No. 161045), the Liao Ning Revitalization Talents Program (No. XLYC1807111) for financial support.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Natural Science Foundation of China [51874071, 51734005]; Fok Ying Tung Education Foundation for Yong Teachers in the Higher Education Institutions of China [161045]; Liao Ning Revitalization Talents Program [XLYC1807111].