Cunningham Spencer, Grammatikopoulos Tassos, Almusned Baian, Henderson Jeffrey Daniel, Azimi Gisele
Laboratory for Strategic Materials, Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College St, Toronto, ON, M5S3E5, Canada.
SGS Canada, 185 Concession Street, Lakefield, ON, K0L2H0, Canada.
Sci Rep. 2025 Aug 8;15(1):29022. doi: 10.1038/s41598-025-14891-3.
Ion-adsorption rare earth element (REE) deposits are a critical resource for strategic materials, yet their characterization and processing remain complex. This study provides a comprehensive mineralogical, chemical, and geochemical analysis of an ionic clay sample from a South American source, integrating multiple characterization techniques, including XRD, SEM-EDX, XPS, ToF-SIMS, TIMA-X, EPMA, and LA-ICP-MS. The results confirm that kaolinite and micas dominate the matrix, with monazite identified as the primary REE-bearing mineral. Yttrium and heavy REEs are primarily hosted in clays, indicating the necessity of ion-exchange leaching for effective extraction. Liberation studies reveal that monazite is best liberated in finer fractions, suggesting a need for targeted pre-concentration strategies. Surface chemistry analyses demonstrate the presence of REEs as adsorbed species and inner-sphere complexes, supporting the use of selective leaching techniques. The study highlights the economic and environmental considerations of REE extraction from ionic clays and provides insights into optimizing recovery processes while mitigating environmental risks. These findings contribute to the growing body of research aimed at diversifying REE supply sources and improving sustainable extraction methods.
离子吸附型稀土元素（REE）矿床是战略物资的关键资源，但其表征和加工仍很复杂。本研究对来自南美某来源的离子黏土样品进行了全面的矿物学、化学和地球化学分析，整合了多种表征技术，包括X射线衍射（XRD）、扫描电子显微镜-能谱仪（SEM-EDX）、X射线光电子能谱（XPS）、飞行时间二次离子质谱（ToF-SIMS）、热电离质谱仪-X（TIMA-X）、电子探针微分析仪（EPMA）和激光剥蚀电感耦合等离子体质谱（LA-ICP-MS）。结果证实，高岭石和云母在基质中占主导地位，独居石被确定为主要的含稀土矿物。钇和重稀土元素主要赋存于黏土中，这表明离子交换浸出是有效提取的必要手段。解离研究表明，独居石在较细粒级中解离效果最佳，这表明需要有针对性的预富集策略。表面化学分析表明，稀土元素以吸附物种和内圈配合物的形式存在，这支持了选择性浸出技术的应用。该研究强调了从离子黏土中提取稀土元素的经济和环境考量，并为优化回收工艺同时降低环境风险提供了见解。这些发现为旨在使稀土供应来源多样化和改进可持续提取方法的日益增多的研究做出了贡献。
