Effect of bastnaesite as reductant on hematite reduction during in-situ suspension magnetization roasting of refractory iron ore under neutral atmosphere

Abstract

The iron tailings of Bayan Obo mines are solid waste, which occupies land area and also causes environmental pollution; however, this waste can be recycled. In this study, based on the characteristics of iron minerals and fluorocarbonate contained in Bayan Obo iron tailings, clean magnetization roasting of iron minerals by bastnaesite from iron tailings during in-situ suspension magnetization roasting in a neutral atmosphere was explored. The results show that for iron tailings with a mass of 12 g, a N 2 gas flow rate of 600 mL/min, and roasting for 5 min at 800 °C, iron concentrate with a 60.44% iron grade at an iron recovery of 76.04% could be obtained. X-ray diffraction analysis showed that the weak magnetic hematite was reduced to strong magnetic magnetite in the neutral atmosphere, without additional reductant. The kinetics of the magnetization roasting of mineral mixtures (bastnaesite and hematite) in a neutral atmosphere showed that the optimal reaction mechanism function was the three-dimensional diffusion model with activation energy of 161.8838 kJ·mol −1 ; this indicates that the reaction was a heterogeneous, diffusion-controlled solid-state reaction.