Exploring rare earth mineral recovery through characterization of riebeckite type ore in Bayan Obo

The aim of this study was to characterize the riebeckite type rare earth ore found in the Bayan Obo deposit, in order to identify the distribution and occurrence of both rare earths and gangue species within the ore. Several analytical techniques were utilized to accomplish this, such as chemical analysis, quantitative XRD, a single polarizing microscope, and a mineral automatic analysis system. The analysis revealed that the primary rare earth minerals (REMs) in the ore were bastnaesite and monazite, with huanghoite, parisite, aeschynite, and fergusonite identified as secondary rare earth minerals. The main gangue species was magnetite, accompanied by smaller quantities of riebeckite and dolomite. The ore was rich in rare earth oxides, with a 3.81 wt% grade. The screen analysis of the pulverized ore indicates that the 43-100 μm fraction is the dominant size, while the finer size fractions below 43 μm contain the bastnaesite and monazite, as well as huanghoite, parisite, aeschynite, and fergusonite. Microstructural characterization showed that the REMs were both coarse-grained and fine-grained, occurring as granular aggregates and fine disseminations within the gangue. Bastnaesite and monazite were the major REMs, with dominant amounts of cerium, lanthanum, praseodymium, and neodymium, while parasite was identified as an impurity. Huanghoite and parisite contained barium and calcium as impurities, respectively. Aeschynite and fergusonite were REMs that included niobium in their composition. Bastnaesite and monazite were found to contain a much higher rare earth content than huanghoite, parisite, aeschynite, and fergusonite. Potential methods for recovering rare earths from this ore, such as magnetic separation and froth flotation, have been identified and may be applicable to similar ferruginous rare earth-bearing ores.