By-product rare earth elements deposits in China and their resource potential

Objective China is the largest producer of rare earth element (REE) and hosts the largest amount of REE resources. Various types of REE deposits have been reported in China, with alkaline-carbonatite related light REE deposits and ion-adsorption heavy REE deposits being the most important ones. Other REE deposit types include REE placers and deposits with REE by-products. Currently, the development of rare earth resources in China is primarily focused carbonatite-alkaline related light REE deposits and ion-adsorption type heavy REE deposits. REE in placer deposits and other REE by-products have not been effectively utilized. Methods Based on existing exploration studies and whole-rock REE geochemistry data analysis, this study provides a brief review of the types and resource potential of deposits with REE by-products in China. Results China's by-products REE resource types include marine sedimentary phosphate, coal, bauxite, and magmatic iron-phosphate deposits. These deposits, particularly marine sedimentary phosphate deposits and bauxite, contain enormous potential REE resources. REEs in bauxite are primarily light REE, with some containing high amount of scandium (Sc). In sedimentary phosphate deposits, the proportion of heavy REEs (including yttrium) is high, particularly in the S−P−Al−Sr rich ores that occur as the layers overlying the phosphorite in the Shifang-type phosphate deposits of Sichuan Province. These S−P−Al−Sr rich ores have significantly higher REE content than phosphorite, with medium and heavy REE accounting for over 50%, along with various critical metals, making these ores highly valuable in terms of both resource and economic significance. Furthermore, REE resources in magmatic (iron) phosphate deposits, coal, oil shale, and gold deposits deserve attention. Conclusions Owing to the lack of detailed exploration data, the full extent of China's by-products REE resources remains unclear. The comprehensive utilization of resources, as well as the technology for REE recovery and extraction, requires improvement. Significance Strengthening the evaluation and comprehensive utilization of China's associated REE resources, particularly by fully utilizing the REE resources associated with phosphate and bauxite deposits, can effectively alleviate the pressure on China's HREE supply. This represents an important measure for implementing China's fundamental national policies on resource conservation and environmental protection.