Recovery of iron from Baotou rare earth tailings by magnetizing roast

Abstract

The difference of physicochemical properties among minerals in Baotou rare earth tailings is not significant, which leads to a great difficulty in separation of minerals. In this article, the process of magnetizing roast and low-intensity magnetic separation was used to recover iron. Effect of calcination temperature, holding time and carbon/oxygen ratio on roasting efficiency was investigated. The parameters evaluating magnetizing roast efficiency and theoretical value were determined. X-ray diffraction (XRD) analysis was used to investigate the conversion of Fe phase after roasting. The results show that the best magnetizing roast conditions are calcination temperature of 650 °C, holding time of 2.5 h, and carbon/oxygen molar ratio of 3.85. The best magnetization rate is 2.36, which is close to the theoretical value of 2.33. Based on experiments of low-intensity magnetic separation under different intensities, the best current intensity is 2.0 A to obtain the best separation results. Under the best condition, the concentrate grade of iron is 45.45 % and the recovery of iron is 68.36 %. Most of rare earth, fluorine, and phosphorus are enriched in the magnetic separation tailings. The XRD analysis shows that Fe exists in Fe2O3 before roasting and exists in Fe3O4 after roasting.