A review of tantalum resources and its production 钽资源及其生产回顾
Xue WEI ^(1){ }^{1}, Long-gong XIA ^(1,2){ }^{1,2}, Zhi-hong LIU ^(1){ }^{1}, Le-ru ZHANG ^(1,3){ }^{1,3}, Qi-hou LI ^(1){ }^{1} 魏雪 ^(1){ }^{1} 、夏龙功 ^(1,2){ }^{1,2} 、刘志宏 ^(1){ }^{1} 、张乐如 ^(1,3){ }^{1,3} 、李启厚 ^(1){ }^{1}1. School of Metallurgy and Environment, Central South University, Changsha 410083, China; 2. National Engineering Research Center for Low Carbon Nonferrous Metallurgy, Central South University, Changsha 410083, China; 3. CINF Engineering Corporation Limited, Changsha 410076, China 1. 中南大学冶金与环境学院，长沙 410083；2. 中南大学国家低碳有色冶金工程研究中心，长沙 410083；3. 中金冶金工程有限公司，长沙 410076
Received 30 August 2022; accepted 11 May 2023 收到日期：2022 年 8 月 30 日；接受日期：2023 年 5 月 11 日
Abstract 抽象的
Tantalum (Ta) is a technology-critical metal, which has important applications in many strategic emerging industries, such as electronic, and aerospace, and there are no substitute materials for Ta so far. The supply crisis of Ta has kept growing globally over the past two decades. This work presents a comprehensive review of tantalum resources and its production. There is less than 300 kt Ta in the earth’s crust, and the production of primary Ta is an energy- and materials-demanding process. Ta can also be recovered from tin smelting slag, lithium ores, end-of-life tantalum products, etc., and they can account for 37%37 \% of the total Ta production. The HF leaching-solvent extraction-sodium potassium fluorotantalate reduction process is the most widely used technology in producing Ta. However, long process and environmental issues have limited the sustainable development of this method. Clean production technologies and efficient recycling of Ta should receive continuous attention. 钽 (Ta) 是一种技术关键金属，在电子、航空航天等许多战略新兴产业中具有重要应用，目前尚无替代材料。过去二十年，全球钽的供应危机持续加剧。本文全面回顾了钽的资源及其生产。地壳中的钽储量不足 300 kt，原生钽的生产是一个耗能耗材的过程。钽也可以从锡冶炼渣、锂矿石、报废钽产品等中回收，这些资源约占钽总产量的 37%37 \% 。HF 浸出-溶剂萃取-氟钽酸钠钾还原工艺是应用最广泛的钽生产工艺。然而，该工艺流程长及环境问题限制了其可持续发展。钽的清洁生产技术和高效回收利用应受到持续关注。
Tantalum (Ta) is a high melting point metal, and has fancy properties, such as good conductivity of heat and electricity, excellent machinability, and high stability in acidic environment, which makes it an important material in many fields, such as electronics, chemicals, aerospace, and medicine [1]. The production and recycling of Ta have significant influences on the development of these strategic emerging industries. However, the resource of tantalum is scarce (less than 300 kt Ta in the earth’s crust) [2], and this could easily lead to Ta supply crisis. Ta has been labelled as critical raw materials by the European Union since 2020, and it is noted that the supply crisis of Ta has kept increasing since 2017. In the era of economic globalization, the 钽 (Ta) 是一种高熔点金属，具有良好的导热性和导电性、优异的可加工性以及在酸性环境中的高稳定性等特性，使其成为电子、化工、航空航天和医药等许多领域的重要材料 [1]。钽的生产和回收对这些战略性新兴产业的发展具有重要意义。然而，钽资源稀缺（地壳中钽储量不足 30 万吨）[2]，这很容易导致钽供应危机。自 2020 年起，钽已被欧盟列为关键原材料，值得注意的是，自 2017 年以来，钽的供应危机持续加剧。在经济全球化时代，
production and supply of tantalum affect the development of related industries. Therefore, it is essential to know the supply chain of tantalum. 钽的生产和供应影响着相关产业的发展，因此了解钽的供应链至关重要。
There are three critical parts of the Ta supply chain, which are Ta resources, metallurgical production and manufacturing, and downstream application. It is urgent to diagnose these critical parts to know how to improve its supply resilience. Limited numbers of works can be found in literatures. However, the researches were mainly focused on the primary resources of tantalum, but the secondary and associated resources are seldom mentioned [3-6]. Referring to the tantalum-making process, some work has been done to study the reduction process of tantalum oxides [7-9]. But the decomposition process of tantalum concentrates and the separation of tantalum and niobium are still not well known. Some studies [10-12] have analysed 钽供应链包含三个关键环节：钽资源、冶金生产制造以及下游应用。亟需对这些关键环节进行诊断，以了解如何提高其供应弹性。文献中相关的研究数量有限。然而，这些研究主要集中在钽的原生资源上，而对次生资源和伴生资源的提及却很少[3-6]。参考钽的生产工艺，一些研究已经对钽氧化物的还原过程进行了研究[7-9]。但钽精矿的分解过程以及钽和铌的分离过程仍不清楚。一些研究[10-12]分析了
the supply and demand of Ta , but they didn’t consider political, economic and cultural factors. 他们关注的是 Ta 的供给与需求，但没有考虑政治、经济和文化因素。
In order to show the life-circle of Ta, this work has made a comprehensive review of the catalogue of resources, applications, supplies and production of the tantalum. Existing theories are analysed and integrated to fill in the gaps in existing research, and suggestions have been put forward to enhance the stability of the tantalum supply chain. 为了展现钽的生命周期，本文对钽的资源、应用、供应和生产目录进行了全面的回顾，并对现有理论进行了分析和整合，以填补现有研究的空白，并提出了增强钽供应链稳定性的建议。
2 Applications and supply of Ta 2 Ta 的应用和供应
2.1 Ta applications 2.1 Ta 应用
Tantalum was firstly separated as a discrete element in 1802 [13], and then started to be used as filaments, rectifiers and detector materials [14,15]. Due to the unique properties, the application of Ta keeps developing. Nowadays, tantalum has been widely used in electronics, chemical industry, aerospace, optics, medical treatment, nuclear industry, etc., and it has been categorized as a technology-critical metal [1,16]. Figure 1 shows the life circle of Ta , including the resources, production, value-adding manufacturing and end-users in each material flow [3,17-23]. 钽于1802年首次作为单质分离出来[13]，随后开始被用作灯丝、整流器和探测器材料[14,15]。由于其独特的性能，钽的应用不断发展。如今，钽已广泛应用于电子、化工、航空航天、光学、医疗、核工业等领域，并被归类为技术关键金属[1,16]。图1展示了钽的生命周期，包括每个物质流中的资源、生产、增值制造和最终用户[3,17-23]。
The electronics industry, accounting for around 50%50 \% of consumption, has consumed the largest part of tantalum, in which met-grade tantalum powder, capacitor-grade tantalum powder and Ta mill 电子行业消耗了大部分的钽，约占消费量的 50%50 \% ，其中金属级钽粉、电容器级钽粉和钽磨
production are used in manufacturing sputtering targets and tantalum capacitors. Ta is an important alloying element in preparing high-temperature alloys, which are key materials for aerospace engines [24]. Tantalum compounds, which are mainly in the forms of tantalum oxide, sodium tantalate, lithium tantalate, etc., are widely used in optics, semiconductors [25] and catalysis industries [26]. 生产用于制造溅射靶材和钽电容器。钽是制备高温合金的重要合金元素，而高温合金是航空航天发动机的关键材料[24]。钽化合物主要以氧化钽、钽酸钠、钽酸锂等形式存在，广泛应用于光学、半导体[25]和催化工业[26]。
Figure 2 shows the compound annual growth rate of tantalum worldwide between 2016 and 2021, by the end product [3,27]. The overall growth rate of tantalum consumption is 4%-5%4 \%-5 \%, and more Ta is needed in preparing sputtering targets, superalloys and Ta compounds. The Ta consumption in the capacitor filed grows by 1.5%1.5 \%, a value below average, and saturation of the market and miniaturisation of capacitors are the main reasons. However, the construction of 5G base stations all over the world and the fast growth of electric vehicles are expected to be new points of growth [28,29] in the future. Due to the low substitutability of tantalum, the consumption in the high-temperature alloy field increases by 7%7 \%, and this is mainly a result of the rapid development of the aerospace field [23]. Ta consumption for sputtering targets and tantalum chemicals will also grow at an above-average rate. The use of tantalum in carbides is expected to decline slowly in following years. 图 2 显示了 2016 年至 2021 年全球钽的最终产品年复合增长率[3,27]。钽消费量的总体增长率为 4%-5%4 \%-5 \% ，制备溅射靶材、高温合金和钽化合物需要更多的钽。电容器领域的钽消费量增长了 1.5%1.5 \% ，低于平均水平，市场饱和和电容器小型化是主要原因。然而，全球 5G 基站的建设和电动汽车的快速增长预计将成为未来新的增长点[28,29]。由于钽的替代性较低，高温合金领域的消费量增长了 7%7 \% ，这主要是由于航空航天领域的快速发展[23]。溅射靶材和钽化学品的钽消费量也将以高于平均水平的速度增长。预计未来几年碳化物中钽的使用量将会缓慢下降。
Fig. 1 Material flows of Ta resources, production, value-added manufacturing and applications between 2015 and 2019 图1 2015-2019年钽资源、生产、增值制造及应用物质流
2.2 Supply 2.2 供应
The supply of tantalum in the world had several disruptions and subsequent price swings in the past 20 years, and this implies resilience and stability problems in the supply chain. Figure 3 shows the global production of tantalum metal from 1999 to 2021 [3,30]. 过去20年，全球钽供应曾多次中断，价格也随之波动，这意味着供应链的韧性和稳定性存在问题。图3显示了1999年至2021年全球钽金属产量[3,30]。
Because of the benign economic climate between 1999 and 2005, global tantalum production gradually increased to 1916 t . However, Ta production has decreased for several years in a row since 2006, and it was mainly a result of the global financial crisis at that time [3]. And then, Ta production started to grow in 2013, and maintained a high production value between 2017 and 2019. This could be explained by the improvement of the global economy, especially the rapid development 1999年至2005年，受经济景气带动，全球钽产量逐步回升至1916吨。然而，自2006年以来，钽产量连续几年下降，主要原因是当时的全球金融危机[3]。此后，钽产量在2013年开始增长，并在2017年至2019年保持了较高的产值。这可以解释为全球经济的改善，尤其是金属材料行业的快速发展。
of global electronics, aerospace and other industries. New Ta projects in Congo, Rwanda, etc., also improve the global tantalum supply [31]. However, the yield decreased slightly in 2019 and 2020, and it is caused by the COVID-19 pandemic. When Ta production resumed in 2021, its supply reached a ten-year peak value of 2494 t [24,32]. Overall, the outlook for tantalum continues to remain robust. Figure 4 shows the tantalum price between 1976 and 2020 [21,33,34]. 全球电子、航空航天和其他行业的钽产量。刚果、卢旺达等国的新钽项目也改善了全球钽供应[31]。然而，2019年和2020年的产量略有下降，这是受新冠疫情影响。2021年钽产量恢复时，其供应量达到了十年来的峰值2494吨[24,32]。总体而言，钽的前景依然强劲。图4显示了1976年至2020年之间的钽价格[21,33,34]。
Tantalum is usually traded with long-term contracts, or parceled on a confidential basis among miners, traders and producers [35,36]. A prisoner’s dilemma is easily caused by some traders and buyers [34], and this may result in short-term market volatility. The price of tantalum will rise in the future when the world gradually recovers from 钽通常以长期合同的形式进行交易，或在矿商、贸易商和生产商之间以保密的方式进行分配[35,36]。一些贸易商和买家很容易造成“囚徒困境”[34]，这可能会导致短期市场波动。未来，随着全球经济逐渐复苏，钽的价格将会上涨。
Fig. 2 Portion of Ta products between 2016 and 2021, and forecast before 2026 图2 2016-2021年钽产品占比及2026年前预测
Fig. 3 Global production of tantalum between 1999 and 2021 图3 1999年至2021年全球钽产量
