Fluidization magnetization roasting of limonite ore using H2 as a reductant: Phase transformation, structure evolution, and kinetics

As a rich iron ore resource, limonite ore is seldom utilized due to compositional and structural complexity and lack of mature processing methods. In this paper, fluidization magnetization roasting and low-intensity magnetic separation were used to process limonite ore. A concentrate with an iron grade of 59.92% and an iron recovery of 87.26% was obtained under these optimum roasting conditions: a temperature of 525 °C, a roasting time of 10 min, and a H2 concentration of 20%. X-ray diffraction, vibrating sample magnetometry, and scanning electron microscopy were used to study the reduction mechanism. The results indicated that the reduction product characteristics greatly changed after roasting. The reduction kinetics followed the nucleation model A2, and the activation energy was 29.62 kJ/mol. This study will provide some guidance for limonite ore utilization.