Rare earth (RE) resources become increasingly critical for emerging and low-carbon technologies. With the rapid development of the global pattern of the rare earth production, consumption and trade, the basic significance of the studies of the flow of the rare earth materials is increasingly recognized at home and abroad in promoting the security of the RE resource supply and the sustainable development of the RE industry, with a great number of papers on the material flow analysis (MFA) focusing on the rare earth elements. This paper firstly reviews the related literature on the origin and the evolution of the REMFA, followed by an in-depth analysis of the limitations of the essential data, the quantitative model and the demand orientation. The following suggestions are made:(1) integrating the data on the RE resource and environment and developing a data platform for the rare earth industry; (2) developing a rare earth quantitative model including a supply-side module consisting of the domestic and foreign virgin and recycled minerals as well as a demand-side module coupling with the industrial revolution and resource; (3) enriching the researches embodying the environmental flow, the value stream and the trade flow of the rare earth elements, to support the high-quality development of the rare earth industry in China.

The rare earth is an important strategic material,but its current global reserves cannot meet the future demand. Therefore, it is urgent to find and develop potential rare earth resources. Based on previous research results, this paper proposes an evaluation index system, with assigned weights, to evaluate the development potential of the global rare earth resources. The following conclusions can be drawn. (1) The evaluation index system is composed of that of the mineral resource development potential and that of the policy environment, with a greater weight for the former and a smaller weight for the latter. (2) In terms of the prospective reserves, China has the largest reserves of the light rare earth, while Denmark (Greenland) has the largest reserves of the heavy rare earth. (3) In terms of the deposit grade, Prado mine in Brazil, Steenkampskraal mine in South Africa, Pea Ridge mine in the United States and Tomtor mine in Russia are among the top rare earth grades in the world. (4) In terms of the deposit development potential, Russia, Denmark (Greenland), Australia, Canada and the United States have the most potential rare earth deposits without counting China. In the face of the increasing supply potential of the global rare earth, China must increase the exploration of its own resources, fully understand the latest development trend of the international rare earth industry, make plans in advance, make full use of the overseas rare earth resources, and ensure the supply security and the industrial chain advantages of China's rare earth resources.

With the increased exchange of the rare earth products among various countries, an international rare earth trade network is formed, reshaping the division of the global rare earth supply chain and the geopolitical pattern. By constructing a trade network for the global rare earth resource-based products, functional materials, and final products trade network in 2000, 2010, and 2017, the global trade flow characteristics of the rare earth resources and the trade relations between major countries or regions are comprehensively shown. It is shown that the rare earth network structure is rather complicated, with heterogeneous trade relations, status, and divisions of countries. The main findings are as follows:(1) The majority of trade relationships and trade amounts are highly concentrated in some critical countries, the supply of the whole trade network would fail, once the critical countries are in trouble; (2) China, the United States, Japan, and other Pacific Rim countries occupy a dominant position in the trade network of the rare earth resource-based products and functional materials; However, Denmark, Germany, and other European countries always occupy a dominant position in the trade network of the final products; (3) The developing countries (e.g., China) only occupy the dominant position in the trade network for the front and middle end products in the rare earths supply chain and play the role of the resource supplier and the intermediate product production factory. Therefore, it is suggested that China should take the following actions:(1) relax the restrictions of the rare earth raw materials import policy and diversify the sources of the rare earth raw materials; (2) increase the export tariff of the low-end functional rare earth materials; (3) encourage the rare earth enterprises to produce and develop the final high-tech and high value-added products.

The electrification of the transportation sector is an important initiative to achieve the carbon neutrality target. It is important to accurately determine the future demand for the rare earth elements (REEs) from the sector of the battery electric passenger vehicle (BEPV), to predict the recovery potential of the materials containing REEs, and to dynamically assess the relationship between the supply and the demand, for promoting the electrification of the transportation sector and ensuring the security of the supply of the REEs. In this paper, three scenarios are identified for the development of the BEPV, namely, the business as the usual scenario, the state policy scenario and the scenario of 1.5 degrees (temperature rising) scenario. By a dynamic material flow analysis, the stocks and the flows of the BEPV are calculated; the future demand, the end-of-life volume and the potential recycling of neodymium (Nd), dysprosium (Dy) and praseodymium (Pr) are predicted. It is shown that:(i) under all scenarios, the BEPV stock shows a growing trend; (ii) the current annual production capacity of Nd, Dy and Pr in China is 15219, 625 and 4509 t, while the future demand is 5700-25900, 1400-6100 and 600-2600 t. If the production capacity is not increased, the demand for Dy of BEPV can not be met, and the demand for Nd of BEPV can only be met in the short term (2020-2040); (iii) recovering the REEs from the BEPV can effectively reduce the demand for the REEs from the virgin source. Therefore, it is recommended to control the supply of the REEs according to each element's features, to increase the directive production plan target for Nd and Dy, to strengthen the technology research and development for recovering the REEs from the BEPV, and to establish an effective recycling system for solid wastes containing the REEs, such as electric vehicles and wind turbines.

The rare earth is widely used in in the field of the catalytic purification of the volatile organic compounds (VOCs) due to its unique chemical properties. This paper reviews the research progress of the reaction mechanism and the application of the rare earth materials in the catalytic purification of volatile organic compounds. According to the actual situation of the VOCs treatment in China, the existing issues are discussed and the counter measures are put forward, for predicting the development of the rare earth materials in the VOCs catalytic purification field.

The tungsten is an important strategic mineral in the industrial manufacturing and the modern national defense. As the largest producer and exporter of the tungsten, China supplies the tungsten-containing products in various forms. However, China's contribution, benefits, and position in the global tungsten value chain have not been well explored. Based on the data of the import and the export of China's tungsten from 1992 to 2018, and on the perspective of the value flow and the material flow, this paper analyzes the global tungsten supply and value chains, and it is shown that China plays the role of the "global tungsten processing giant" in the supply chain, but still in a subordinate position in the value chain, with the risk of "locked in the low value-added stage" and "highly dependent in the high value-added stage". Several specific features are as follows:(1) From the perspective of the material flow, China is a net-exporter of the tungsten, with the scale of the net-export continuously expanding, exporting mostly the tungsten semi-products and importing mostly the primary and metal tungsten products. (2) From the perspective of the value flow, the trade value and the surplus of China's tungsten show a significant growth trend, while the unit price in the imports is much higher than that in the exports. (3) By combining the perspectives of the material and value flows, the total volume and the structure of China's tungsten trade show asymmetric characteristics. Based on this analysis, to promote its competitiveness in the global tungsten value chain, China has to:(1) encourage the import of the tungsten raw materials such as the tungsten concentrate and the tungsten waste to enhance the tungsten material security; (2) increase the export tariff of the tungsten semi-products and the low-end tungsten metal products to encourage the enterprises to focus on the deep processing; (3) support the enterprises of the tungsten metal products to improve the competitiveness of the export products.

With increasing environmental pollution caused by the rare earth production, the environmental regulations are the key to the sustainable development and the international competitiveness of the rare earth industry in China. This paper reviews the development of the environmental regulations in China, the United States and Australia and compares some key aspects, including the safety management of the radioactive pollutants, the land reclamation, the air pollution management and the environmental taxes, and the main findings are as follows. (1) In China, the system of the environmental laws and regulations for the rare earth industry has been gradually established since 2012, containing effectively the spread of the environmental pollution, while somehow affecting the supply of the rare earths. (2) In the United States and Australia, regulations were established earlier, as high environmental barriers for the production of the rare earths. Accordingly, the producers of the rare earths and the related downstream industries shifted their business to other countries, which poses challenges for the United States and Australia to restore their production of the rare earths. (3) To reduce the high cost caused by the environmental regulations, based on the international trade, the United States and Australia have established three channels of transferring the environmental pollution, i.e., the production capacity transfer, the decree transfer and the production pattern transfer. As a result, countries such as Malaysia were driven to undertake severe environmental costs. Based on these international perspectives, we highlight the importance of the lessons learned in other countries such as the United States and Australia, and the improvement of the measures for regulating the rare earth industry in China and the global rare earth environmental governance system, in order to reduce the environmental pollution and to rationally optimize the global supply chain of the rare earths.

The critical minerals, are referred to those strategic non-fuel minerals that are critical to the national economy and defense security but under high supply risks. The U.S. has focused on its supply security since 1930s. This paper reviews the research progress of the critical minerals and the related policies in the U.S., with several key findings:(1) the focus behind the U.S. mineral criticality policy has shifted from the supply security-oriented to the national competitive strategy-oriented system; (2) the methodology of the criticality assessment is shifted from the static assessment of the mineral-based risks to the dynamic assessment of the manufacturing-based supply risks; (3) the orientation of the supply chain management policy is shifted from the deglobalization of the supply chains to the de-coupling from China; (4) the object of the criticality assessment is shifted from the minerals to the emerging technologies related to the containment of China's development. The evolution of the U.S. strategy for the critical minerals is influenced by its excessive expansion of the national security agendas, the resource demand of the manufacturing reshoring, the return of Cold War Mentality and the intention of maintaining the advantage in the overall national strength. Therefore, China should develop unique criticality assessment frameworks according to the China's reality, strengthen the industry-university-research cooperation in the emerging technologies and the international cooperation in the critical minerals supply chains.