The Occurrence and Distribution of REE Minerals in Fluorite-Type Ores in Bayan Obo：Constraints From Raman Mapping
ZHANG Tie-zhu1, 2, ZHANG Yu-xuan2, 3, LIU Sai-yu2, 4, LI Hang-ren2, XU Wen-ce1, 2, ZHANG Jin-shan1*, OUYANG Shun-li2*, WU Nan-nan4
1. Mining Research Institute of Inner Mongolia University of Science and Technology, Baotou 014010, China
2. Key Laboratory of Integrated Exploitation of Bayan Obo Multi-Metal Resources, Inner Mongolia University of Science and Technology, Baotou 014010, China
3. School of Material and Metallurgy, Inner Mongolia University of Science and Technology, Baotou 014010, China
4. College of Science, Inner Mongolia University of Science and Technology, Baotou 014010, China
Abstract：Bayan Obo is famous for its rich mineral resources and huge reserves. Monazite is one of the main raw materials of rare earth, widely used in metallurgy, Military and chemical materials. The mineralogical characteristics of Bayan Obo have been studied. However, we need to understand the occurrence state of rare earth minerals at the present stage with the increased mining depth and the original minerals. Here, the Raman Mapping and Scanning Electron Microscope (SEM) and Energy Dispersive Spectrometer (EDS) were used to study the occurrence characteristics of minerals associated with REE in Bayan Obo. The EDS and energy spectrum analysis results showed that the minerals of the scanning area were composed of fluorite, barite, monazite, apatite, and iron-bearing minerals. Basis minerals were fluorite (CaF2) under the confocal microscopic diagram scanning by Raman Mapping analysis. The characteristic peaks of the Raman spectrum were generally appeared in (220~650 cm-1), which was slightly different from previously reported results. The larger grains were barite (BaSO4), typical sulfate minerals. The medium-size minerals were monazite (Ce, La, Nd) PO4, whereas the fine particles were apatite minerals （Ca5[PO4]3F）. Monazite and apatite share the same phosphate root structure with different binding types of external metal cations and Raman peaks. Raman Mapping and EDS technology analyzed the relationships between occurrence characteristics and distribution of minerals. The monazite particles were in the form of plates or blocks and sizes about 50~120 μm. It was distributed between barite and apatite or between apatite and fluorite. The barite particles were coarsely distributed as bulk aggregates, and the size was 50~200 μm. It always grows closely with monazite particles. It was granular or massive, which was distributed similarly to the infection around in fluorite. A small amount of apatite and monazite was distributed metasomatism into irregular paragenesis. There were most of the monomer apatite distributed among around monazite and barite. The fluorites were the most abundant account for about 55% of minerals. There were co-associated with monazite, barite, apatite, and iron ore. It’s formation period that had been judged from the occurrence state should be earlier than others. It was multi-genesis and complicated associated minerals in the Bayan Obo deposit. EDS can analyze the basic relationship of mineralogy, but the energy spectra of monazite and barite partly coincide. The reason was that the excitation energy lineages of Ba and S are too close to the rare earth elements Ce, La, and Nd, and the energy spectral low resolution. Raman mapping imaging technology has the advantages of simplicity and reliability in mineral identification, making up for EDS misjudgment analysis. Raman mapping can provide a new identification idea for Mineralogical analysis of minerals and provide a reference Raman spectrum for mineral identification of Bayan Obo.
张铁柱，张宇轩，刘赛余，李航任，徐文策，张金山，欧阳顺利，吴楠楠. 拉曼Mapping研究白云鄂博萤石型稀土矿物赋存特征及分布规律[J]. 光谱学与光谱分析, 2021, 41(12): 3776-3781.
ZHANG Tie-zhu, ZHANG Yu-xuan, LIU Sai-yu, LI Hang-ren, XU Wen-ce, ZHANG Jin-shan, OUYANG Shun-li, WU Nan-nan. The Occurrence and Distribution of REE Minerals in Fluorite-Type Ores in Bayan Obo：Constraints From Raman Mapping. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2021, 41(12): 3776-3781.
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