Comparative mineralogical characterization of REEs ore samples from the Mushgai Khudag and Lugiin Gol deposits, Mongolia

Mongolia, situated in the Central Asian orogenic belt, is characterized by geology that is highly conducive to the abundance of mineral resources, including significant rare earth elements (REEs) reserves. However, limited knowledge of the mineralogy of its deposits has hindered the development of efficient REEs extraction methods. This study presents a detailed investigation of the mineralogical characteristics of Mongolian ores and analyzes their compositions, mineral associations, liberation, and REEs concentrations via advanced analytical techniques, including the TESCAN Integrated Mineral Analyzer (TIMA). Additionally, the BCR sequential extraction method was employed to determine the binding and leaching properties of REEs. Our results revealed that the two ore samples were predominantly rich in light rare earth elements (LREEs), with REE-bearing minerals closely associated with gangue minerals such as calcite, albite, and quartz, leading to poor liberation. The extraction data indicated that >85 % of the REEs in the Mushgai Khudag deposit were retained in the residual fraction, whereas in the Lugiin Gol deposit, the majority of the REEs were associated with the reducible fraction. These findings underscore the challenges associated with extracting REEs from Mongolian deposits, which demand stringent conditions for effective recovery. This research contributes valuable insights into the complex mineralogy of Mongolian REEs deposits, offering a foundation for future advancements in REE extraction technologies.