Separation of Iron and Phosphorus from High-Phosphorus Oolitic Hematite Using Direct Reduction and Magnetic Separation

Abstract

To efficiently utilize high-phosphorus oolitic hematite, phosphorus should be separated from iron, thus a process of direct reduction and magnetic separation was proposed. The physicochemical properties of oolitic hematite before and after treatment were characterized through analysis of the chemical composition, X-ray diffraction (XRD), scanning electron microscope (SEM), and energy-dispersive X-ray spectroscopy (EDS). The influence of various experimental parameters on the upgrading iron and phosphorus removal was investigated, including reduction temperature, reduction dose, and reduction time. Additionally, mass conservation was employed to determine the distribution and migration path of phosphorus from apatite to the slag, gas phase, and metallic iron. Results indicated that the optimal experimental conditions for achieving high recovery ratios of metallic iron and high removal ratios of phosphorus were the temperature of 1200 °C, reduction time of 120 min, and C/O molar ratio of 1.2. Under these conditions, 95.28% of iron was collected as metallic iron, while 70.02% of phosphorus remained in the slag residue. Therefore, the proposed method effectively restrained the reduction of apatite, which led to a good separation of iron from phosphorus.