Microwave-assisted reduction roasting—magnetic separation studies of two mineralogically different low-grade iron ores

• Published in: International journal of minerals, metallurgy and materials Vol. 27; no. 11; pp. 1449 - 1461
• Main Authors: Roy, Subhnit K., Nayak, Deepak, Dash, Nilima, Dhawan, Nikhil, Rath, Swagat S.
• Format: Journal Article
• Language: English
• Published: Beijing University of Science and Technology Beijing 01.11.2020; Springer Nature B.V; Mineral Processing Department, CSIR-Institute of Minerals and Materials Technology, Bhubaneswar 751013, India%Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Roorkee 247667, India
• Subjects: Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Composites; Corrosion and Coatings; Electron probe microanalysis; Glass; Iron compounds; Iron ores; Iron oxides; Light microscopy; Magnetic measurement; Magnetic separation; Magnetite; Materials Science; Metallic Materials; Natural Materials; Optical microscopy; Recovery; Reduction; Roasting; Surfaces and Interfaces; Thin Films; Tribology; X-ray diffraction; magnetic separation; goethitic ore; reduction roasting; microwave; titano-magnetite ore
• ISSN: 1674-4799; 1869-103X
• DOI: 10.1007/s12613-020-1992-5

The microwave-assisted reduction behaviours of two low-grade iron ores having a similar Fe content of 49wt% but distinctly different mineralogical and liberation characteristics were studied. Their performances in terms of the iron grade and recovery as obtained from statistically designed microwave (MW) roasting followed by low-intensity magnetic separation (LIMS) experiments were compared. At respective optimum conditions, the titano-magnetite ore (O1) could yield an iron concentrate of 62.57% Fe grade and 60.01% Fe recovery, while the goethitic ore (O2) could be upgraded to a concentrate of 64.4% Fe grade and 33.3% Fe recovery. Compared with the goethitic ore, the titano-magnetite ore responded better to MW heating. The characterization studies of the feed and roasted products obtained at different power and time conditions using X-ray diffraction, optical microscopy, vibrating-sample magnetometry, and electron-probe microanalysis explain the sequential reduction in the iron oxide phases. Finally, taking advantage of the MW absorbing character of the titano-magnetite ore, a blend of the same with the goethite-rich ore at a weight ratio of 60:40 (O2: O1) was subjected to MW roasting that resulted in a concentrate of 61.57% Fe grade with a Fe recovery of 64.47%.