Assessment of rare earth element potential in different geological formations of Sri Lanka

Abstract

In recent years, the global demand for rare earth elements (REEs) has been burgeoning due to the wide range of applications in numerous modern and green energy technologies. Although China was dominating the REE market, now the reliance on Chinese REE production has begun to ease with the global attempts to explore new REE resources outside China. This growing global competition coupled with demand escalations provides an opportunity for developing countries like Sri Lanka to start explorations for new viable REE sources to become a potential REE supplier to the global REE market. Therefore, the present study focuses on assessing the REE potential in different geological formations in Sri Lanka based on their origins and occurrences. Accordingly, representative samples from the Eppawala phosphate deposit (EPD) (n=60), Ginigalpelessa serpentinite deposit (n=32), beach placers on the northeast coast (Verugal: n=18 and Pulmoddai: n=26) and the southwest coast (n=18), alluvial placers in the Walave river basin (n=20), granites at Thonigala (n=17), Massenna (n=10), Arangala (n=6), and Ambagaspitiya (n=6), and Ratthota pegmatite (n=6) were analyzed for their REE contents. Based on the results, the EPD, Massenna and Arangala granites, and Pulmoddai deposit were the most prospective REE sources in Sri Lanka. However, due to technological and environmental challenges associated with granitic occurrences and the Pulmoddai deposit when converting them into exploitable mineral reserves, the EPD was identified as the most prospective source in Sri Lanka in the present study. Despite the relatively low REO grade (~0.48% ΣREE2O3) in the EPD compared to other similar global occurrences, this deposit is significantly enriched in critical and highly demanded REEs like Nd, Pr, and Tb. Therefore, with upgraded extraction techniques, the EPD could become a potential diverse source of REEs that may contribute to maintaining a sustainable REE supply chain in the future.