Tellurium and Selenium Cycling and Supply

从化石燃料转向低二氧化碳技术将导致某些基本原材料的更大消耗。碲(Te)和硒(Se)是光伏(PV)太阳能电池板中必不可少的E-tech元素。它们很稀有，只有少量开采；它们在地球内的位置鲜为人知；回收它们在技术和经济上具有挑战性；它们的回收和再循环对环境有重大影响。然而，需求预计将激增，光伏薄膜生产将消耗大部分Se，并在2020年前超过Te的供应。目前，这些元素只能作为铜和镍精炼的副产品获得，它们从这些矿石中的回收率正在下降，导致供应风险，可能阻碍PV的推广。满足未来需求需要新的方法，包括从副产转向富Se和Te矿石的定向加工。我们的研究旨在通过了解支配这些元素在地壳中如何和在哪里聚集的过程，并通过使它们能够以最小的环境和经济代价回收它们，来解决供应安全问题。这将涉及来自勘探者、生产商、加工商、终端用户和学术界的20个行业合作伙伴，贡献超过50万GB。岩浆环境：开发准确测量矿物和岩石中Se和Te的方法--它们通常在非常低的浓度下出现，由于缺乏可靠的数据，研究受到阻碍。通过实验确定Te和Se在硫化物液体和岩浆之间的分布--需要预测它们的出现地点--并使用众所周知的岩浆系统来证实这些数据。评估已知但知之甚少的“碱性”岩浆在热液Te矿化中的作用。热液环境：测量不同矿物对Te和Se的偏好，以预测矿物宿主并设计矿石处理策略。模拟与碱性岩浆有关的热液系统中的水-岩反应，以检验已知的组合是否受水化学控制。临界区环境：确定Te和Se在风化环境中的化学形态和分布，以了解溶解性、流动性和生物有效性。这反过来又控制了勘查的地球化学晕，并为微生物提取提供了天然的类似物。沉积环境：确定地质和微生物对煤中Se和Te的赋存、迁移和浓缩的控制--可能是Se的主要储存库。确定氧化和还原沉积物中Se和Te浓缩的地质和微生物机制--并将这些机制作为潜在的工业分离过程进行评估。微生物处理：确定有效的Se和Te沉淀微生物，并优化从溶液中回收的条件。评估从矿石和渗滤液中生物回收Se和Te的潜力，并设计一个生物反应器。离子液体处理：评估离子溶剂作为一种回收方法溶解Se和Te矿石矿物的能力。优化离子液体处理并进行中试示范。这是首次对地壳中的Te和Se循环进行整体研究，并与开创性的矿石处理研究相结合。我们的成果将用于工业：高效勘探新的Te和Se矿床；调整加工技术，从现有矿藏中回收Te和Se；使用新的低能源、低环境影响的回收技术。我们的结果将被国家机构用于改善对终端用户未来Te和Se供应的估计，终端用户将受益于对供应安全的信心增强，并将用于国际政府规划未来的能源战略。公众将通过不受阻碍地发展可持续环境技术来支持低二氧化碳社会而受益。

A shift from fossil fuels to low-CO2 technologies will lead to greater consumption of certain essential raw materials. Tellurium (Te) and selenium (Se) are 'E-tech' elements essential in photovoltaic (PV) solar panels. They are rare and mined only in small quantities; their location within the Earth is poorly known; recovering them is technically and economically challenging; and their recovery and recycling has significant environmental impacts. Yet demand is expected to surge and PV film production will consume most Se mined and outstrip Te supply by 2020. Presently, these elements are available only as by-products of Cu and Ni refining and their recovery from these ores is decreasing, leading to a supply risk that could hamper the roll-out of PV.Meeting future demand requires new approaches, including a change from by-production to targeted processing of Se and Te-rich ores. Our research aims to tackle the security of supply by understanding the processes that govern how and where these elements are concentrated in the Earth's crust; and by enabling their recovery with minimal environmental and economic cost. This will involve >20 industrial partners from explorers, producers, processors, end-users and academia, contributing over £0.5M. Focussed objectives across 6 environments will target key knowledge gaps.The magmatic environment: Develop methods for accurately measuring Se and Te in minerals and rocks - they typically occur in very low concentrations and research is hampered by the lack of reliable data. Experimentally determine how Te and Se distribute between sulfide liquids and magmas - needed to predict where they occur - and ground-truth these data using well-understood magmatic systems. Assess the recognised, but poorly understood, role of "alkaline" magmas in hydrothermal Te mineralisation.The hydrothermal environment: Measure preferences of Te and Se for different minerals to predict mineral hosts and design ore process strategies. Model water-rock reaction in "alkaline" magma-related hydrothermal systems to test whether the known association is controlled by water chemistry.The critical zone environment: Determine the chemical forms and distributions of Te and Se in the weathering environment to understand solubility, mobility and bioavailability. This in turn controls the geochemical halo for exploration and provides a natural analogue for microbiological extraction.The sedimentary environment: Identify the geological and microbiological controls on the occurrence, mobility and concentration of Se and Te in coal - a possible major repository of Se. Identify the geological and microbiological mechanisms of Se and Te concentration in oxidised and reduced sediments - and evaluate these mechanisms as potential industrial separation processes.Microbiological processing: Identify efficient Se- and Te-precipitating micro-organisms and optimise conditions for recovery from solution. Assess the potential to bio-recover Se and Te from ores and leachates and design a bioreactor.Ionic liquid processing: Assess the ability of ionic solvents to dissolve Se and Te ore minerals as a recovery method. Optimise ionic liquid processing and give a pilot-plant demonstration.This is the first holistic study of the Te and Se cycle through the Earth's crust, integrated with groundbreaking ore-processing research. Our results will be used by industry to: efficiently explore for new Te and Se deposits; adapt processing techniques to recover Te and Se from existing deposits; use new low-energy, low-environmental impact recovery technologies. Our results will be used by national agencies to improve estimates of future Te and Se supplies to end-users, who will benefit from increased confidence in security of supply, and to international government for planning future energy strategies. The public will benefit through unhindered development of sustainable environmental technologies to support a low-CO2 society.