Byproduct Surplus: Lighting the Depreciative Europium in China's Rare Earth Boom

Selective recovery of europium from real acid mine drainage using modified Cr-MIL and SBA15 adsorbents

The successful adoption and widespread implementation of innovative acid mine drainage treatment and resource recovery methods hinge on their capacity to demonstrate enhanced performance, economic viability, and environmental sustainability compared to conventional approaches. Here, an evaluation of the efficacy of chromium-based metal-organic frameworks and amine-grafted SBA15 materials in adsorbing europium (Eu) from actual mining wastewater was conducted. The adsorbents underwent comprehensive characterization and examination for their affinity for Eu. Cr-MIL-PMIDA and SBA15-NH-PMIDA had a highest Langmuir adsorption capacity of 69 mg/g and 86 mg/g, respectively, for an optimum level of pH 4.8. Preferential adsorption tests followed using real AMD collected at a disused mine in the north of Norway. A comparative study utilizing pH-adjusted real AMD revealed that Cr-MIL-PMIDA (88%) exhibited slightly higher selectivity towards Eu compared to SBA15-NH-PMIDA (81%) in real mining wastewater. While Cr-MIL-PMIDA displays excellent properties for the selective recovery of REEs, practical challenges related to production costs and potential susceptibility to chromium leaching make it less appealing for widespread applications. A cost-benefit analysis was then undertaken to quantify the advantages of employing SBA15-NH-PMIDA material. The study disclosed that 193.2 g of EuCl3 with 99% purity can be recovered by treating 1000 m3 of AMD.

Unlocking Dysprosium Constraints for China's 1.5 °C Climate Target

Some key low-carbon technologies, ranging from wind turbines to electric vehicles, are underpinned by the strong rare-earth-based permanent magnets of the Nd, Pr (Dy)-Fe-Nb type (NdFeB). These NdFeB magnets, which are sensitive to demagnetization with temperature elevation (the Curie point), require the addition of variable amounts of dysprosium (Dy), where an elevation of the Curie point is needed to meet operational conditions. Given that China is the world's largest REE supplier with abundant REE reserves, the impact of an ambitious 1.5 °C climate target on China's Dy supply chain has sparked widespread concern. Here, we explore future trends and innovation strategies associated with the linkage between Dy and NdFeBs under various climate scenarios in China. We find China alone is expected to exhaust the global present Dy reserve within the next 2-3 decades to facilitate the 1.5 °C climate target. By implementing global available innovation strategies, such as material substitution, reduction, and recycling, it is possible to avoid 48%-68% of China's cumulative demand for Dy. Nevertheless, ongoing efforts in REE exploration and production are still required to meet China's growing Dy demand, which will face competition from the United States, European Union, and other countries with ambitious climate targets. Thus, our analysis urges China and those nations to form wider cooperation in REE supply chains as well as in NdFeB innovation for the realization of a global climate-safe future.

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.

Mapping the Global Anthropogenic Chromium Cycle: Implications for Resource Efficiency and Potential Supply Risk

Chromium (Cr) is a critical metal due to its non-substitutable application in the metallurgy industry and highly uneven distribution of global reserve. However, there is a lack of in-depth analysis of global Cr flow patterns and its trade networks among individual cycles, which leaves the potential barriers and opportunities unexplored for improving chromium resource efficiency. Here, we employ a trade-linked multilevel material flow analysis (MFA) to map the global anthropogenic Cr cycle for year 2019. Social network analysis is also used to identify the key countries involved in the global Cr trade network. The results highlight that the global Cr cycle depends substantially on international trade in different forms, of which stainless steel is the leading application. Although South Africa, Kazakhstan, and Turkey are the major Cr primary resource suppliers, China and India play substantial roles in manufacturing Cr-containing products. Regional disparities exist in the scrap contents of individual country cycles, varying from 7% (uncertainty ranges from 4 to 11%) in China to 88% (uncertainty ranges from 87 to 89%) in India. Additionally, several countries are essential in the global Cr redistribution and in the connectivity of the Cr trade network, which may lead to their strong import dependence and even supply disruption.

Uncovering the Key Features of Dysprosium Flows and Stocks in China

Dysprosium (Dy) is a critical rare earth element and plays an indispensable role in clean energy technologies, such as wind turbines and electric vehicles. However, its flows and stocks in the whole life cycle and potential barriers to sustainable supply remain unclear, although the demand for Dy is increasing and its reserves are limited. This study aims to track China's Dy cycle for the period of 2000 to 2019 by employing dynamic material flow analysis. The results show that (1) demand for Dy had increased by 117-fold, with an accumulative use of 37,317 tons, of which 50% was obtained from illegal mining; (2) 33% of the overall Dy resource was used in wind turbines in 2019, followed by air conditioners and electric vehicles (22 and 17%, respectively); (3) China's net Dy export had increased by 10-fold from 2000 to 2019, with Dy concentrates and final products being the dominant import and export products, respectively. Illegal mining, inadequate recycling policies, and limited Dy supply sources are potential barriers influencing sustainable Dy supply.

Toward carbon neutrality: Uncovering constraints on critical minerals in the Chinese power system

China has set up its ambitious carbon neutrality target, which mainly relies on significant energy-related carbon emissions reduction. As the largest important contributing sector, power sector must achieve energy transition, in which critical minerals will play an essential role. However, the potential supply and demand for these minerals are uncertain. This study aims to predict the cumulative demand for critical minerals in the power sector under different scenarios via dynamic material flow analysis (DMFA), including total demands, supplies and production capacities of different minerals. Then, these critical minerals are categorized into superior and scarce resources for further analysis so that more detailed results can be obtained. Results present that the total minerals supply will not meet the total minerals demand (74260 kt) in 2060. Serious resource shortages will occur for several key minerals, such as Cr, Cu, Mn, Ag, Te, Ga, and Co. In addition, the demand for renewable energy will be nearly fifty times higher than that of fossil fuels energy, implying more diversified demands for various minerals. Finally, several policy recommendations are proposed to help improve the overall resource efficiency, such as strategic reserves, material substitutions, and circular economy.