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.
Cunningham et al. (2025) studied this question.