Measuring the anthropogenic cycles of light rare earths in China: Implications for the imbalance problem.

Light rare earth elements (LREEs) are of strategic importance for low carbon transition and decarbonization. However, the imbalance between LREEs exists and a systematic understanding of their flows and stocks is lacking, which impedes the attainment of resources efficiency and exacerbates the environmental burdens. This study examines the anthropogenic cycles and the imbalance problem of three representative LREEs in China, the largest LREEs producer in the world, including cerium (the most abundant), neodymium and praseodymium (the fastest demand-growing). We find that 1) from 2011 to 2020, the total consumption of Nd and Pr increased by 228 % and 223 %, respectively, mainly attributed to the increasing demand of NdFeB, whereas that of Ce increased by 157 %; 2) the supply insufficiency of Nd and Pr under the current quota system accumulated to 138,086 tons and 35,549 tons, respectively, while the oversupply of Ce reached 63,523 tons; and 3) China has become a net importer of LREEs concentrates, and a net exporter of LREEs in the form of intermediate and final products, imposing further burdens to the domestic environment. It is clear that the imbalance of LREEs occurred during the study period, raising urgent needs to adjust the LREEs production quotas, seek other Ce applications, and eliminate illegal mining.