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Recovery of Fe and V via selective reduction–magnetic separation of vanadium-titanium magnetite concentrate

Liu Liwei, Li Guofeng, Zhao Libing, Li Jinpeng, Li Yanfeng

Physicochemical Problems of Mineral Processing

2022

Vol. 58, iss. 1

50--62

With the aim of separating Fe and V, a vanadium-titanium magnetite concentrate was selectively reduced, followed by magnetic separation. The processes accompanying reduction of the vanadium-titanium magnetite concentrate were investigated using thermodynamic simulation, experiments, scanning electron microscopy, and electron probe microanalysis. Appropriate reduction conditions and controlling the amount of CaCO3 promoted the reduction of Fe-containing minerals to metallic Fe. V was released from magnetite, ilmenite, and titanomagnetite, and was inhibited to reduce to metallic V, leading to V enrichment in the non-magnetic products in the form of oxides. Moreover, the Fe particles wrapped the slag phase when the amount of CaCO3 exceeded 8%, which is unfavourable for the magnetic separation of Fe and V. Magnetic products with an Fe content of 87.19%, Fe recovery of 82.62%, V content of 0.09% and non-magnetic products with a V content of 1.00% and a V recovery of 85.49% were obtained when the vanadium-titanium magnetite concentrate was reduced for 100 min at 1623 K with a C/O molar ratio of 2.5 and 8% CaCO3, followed by separating at a magnetic field strength of 85 mT.

Effect of particle size on reduction kinetics of hematite ore in suspension roaster

Gaob Peng, An Yaxiong, Li Guofeng, Han Yuexin

Physicochemical Problems of Mineral Processing

2020

Vol. 56, iss. 3

449--459

Suspension magnetization roasting followed by magnetic separation is an innovative and effective way to recover iron from refractory iron ores, and the particle size of the ore greatly affects the roasting index. To identify the effect of particle size on the reduction kinetics for the transformation of hematite to magnetite, a high-purity hematite ore with different size fractions were isothermally reduced using a suspension roaster. The pure hematite ore was divided into -1000+500 µm, -500+150 µm, -150+74 µm, -74+37 µm and -37 µm size fractions, while the gas mixture of CO and CO2 with a volume ratio of 1:4 was used as reductant. The results showed that the most suitable mechanism function for the reduction of -37 µm size fraction hematite ore is the Avrami-Erofeev model. In the case of -500+37 µm size fraction, the reduction process can be described by first-order chemical reaction model. For -1000+500 µm size fraction, the reduction of hematite ore is restricted by the second-order chemical reaction. In addition, scanning electron microscopy (SEM) analysis results demonstrated that the transformation of hematite particles to magnetite is in accordance with the characteristics of shrinking core model. The phase transformation primarily occurs at the edge of hematite particles and then develop towards the inner side of particles. The findings of this paper provide a theoretical basis for the development and utilization of refractory hematite ore via suspension magnetization roasting technology.