Deep Eutectic Solvents and the Future of the Critical Metals Circular Economy

废弃电气电子设备（WEEE）是世界上增长最快的废物流，每年产生约5400万吨（Mtpa）。这一废物流中所含金属的价值为430亿英镑，其中包括转向低碳经济所需的许多珍贵和关键金属，其中大部分都被填埋了。回收的报废电子电气设备使用效率低且对环境影响大的冶炼和精炼工艺进行处理，需要大量的能源、水和向大气中排放大量的二氧化碳，这与低碳经济的承诺不符。英国是最大的报废电子电气设备生产国之一（23.9公斤/人；160万吨/年）（UN GEM 2020），由于国内和先进的回收能力有限，英国出口了大量报废电子电气设备用于回收。因此，英国需要一种国内回收方案，不仅可以回收和提取报废电子电气设备中被困的金属价值，而且可以以更有效和环境可持续的方式进行回收。这项研究将建立在目前英国对一种新型化学的应用研究的基础上，这种化学被称为深共晶溶剂（DES），用于从WEEE中提取金属。该研究旨在创造一种低影响的替代现有WEEE回收方法，减少金属生产对环境的影响，并使英国成为环境可持续金属回收和生产领域的世界领导者，并带来GDP增长和创造就业机会的相关经济效益。DES是建立在非常简单的化学基础上的，其中像原维生素B4（在鸡饲料中）这样的分子与有机分子(如柠檬酸（在水果中）或尿素（一种肥料）相结合，形成擅长溶解金属的液体。它们是一类可生物降解的、对环境无害的、低成本的、可回收的、无水的、不含强酸和强碱液体的材料，是英国开发的，作为目前使用的高度危险、有毒和对环境有害的工艺的替代品。它们可以从开采的矿石中溶解金属，也可以从WEEE中溶解金属，因此可以应用于多个金属加工行业。它们不会产生大量的废物、温室气体或其他微粒排放，需要的能源更少，而且在溶解各种不同金属方面效率很高。这使它们成为回收和回收金属的绝佳溶剂，这些金属可以用于低碳经济，如镍、铜、金等，这些金属在向电气化的转变中比化石燃料的使用更有用处。DES还可以提取其他金属，包括稀土元素（REE），这对于生产用于混合动力汽车和风力涡轮发电机的高效永磁电机至关重要。稀土元素（REE）回收是英国经济的另一个关键产业，然而，中国目前生产了世界上80%左右的稀土元素。此外，目前只有1%的稀土元素被回收利用。目前的流程在许多方面与当前报废电子电气设备回收流程中使用的流程相似，因此也需要更清洁的替代品。这为英国提供了一个令人兴奋和关键的机会，可以开发新的低能耗和更环保的技术，成为该行业的全球领导者。这将消除对中国等国供应这些金属的依赖。最新的环境审计委员会（EAC）报告呼吁增加报废电子电气设备的回收利用，并建立一个成熟的英国工业，确保中国以外的稀土供应是多格尔银行风电场等可再生项目所必需的，这是国家和欧洲层面的优先事项。这项研究可以通过回收和循环利用关键金属来帮助解决这两个问题，从而实现英国的低碳循环经济。DES正是推动英国金属回收革命向前发展的技术。

Waste Electrical and Electronic Equipment (WEEE) is the world's fastest growing waste stream, generating approximately 54 million tonnes per annum (Mtpa). The value of the metals contained in this waste stream is valued at £43Bn, including numerous precious and critical metals needed to move to a low carbon economy, most of which is lost to landfill. WEEE that is recycled is processed using inefficient and environmentally impactful smelting and refining processes that require significant energy, water use and discharge of large quantities of CO2 into the atmosphere, a processes that is at odds with commitments to a low carbon economy. The UK, which is one of the largest WEEE producers (23.9kg/person; 1.6mtpa) (UN GEM 2020), exports huge volumes of WEEE for recycling due to limited domestic and advanced recycling capacity. There is therefore a need within the UK for a domestic recycling option that can not only recycle and extract the trapped metal value within WEEE but do so in a more efficient and environmentally sustainable way. This research will build on current UK research into the application of a novel chemistry, known as Deep Eutectic Solvents (DES), in the extraction of metals form WEEE. The research aims to create a low impact alternative to current WEEE recycling methods, reducing the environmental impact of metals production and establishing the UK as a world leader in the field of environmentally sustainable metals recycling and production with the associated economic benefits of GDP increase and job creation. DES are based on very simple chemistry where molecules such as pro-vitamin B4, (in chicken feed), are combined with organic molecules such as citric acid, (in fruit), or urea, which is a (fertiliser) to form liquids that excel at dissolving metals. They are a class of biodegradable, environmentally benign, low cost, recyclable, water free, free of strong acid and base liquids that were developed in the UK as an alternative to highly dangerous, toxic and environmentally hazardous processes that are currently employed. They can dissolve metals out of mined ores and also WEEE, so can be applied to multiple metal processing industries. They do not produce large amounts of waste, greenhouse gases or other particulate emissions, require less energy and are highly efficient at dissolving a wide range of different metals. This makes them excellent solvents for recycling and recovery of metals that can then be used in the low carbon economy, such as nickel, copper, gold etc. which have uses in the move to electrification over fossil fuel use. DES can also extract other metals, including Rare Earth Elements (REE) which are crucial in the production of efficient permanent magnet motors for hybrid-electric vehicles and wind turbine generators.Rare Earth Element (REE) recovery is another critical industry to the UK economy however, China currently produces around 80% of the world's REE. Furthermore, only 1% of REE are currently recycled. The current processes are in many ways similar to the ones that are used in current WEEE recycling processes and so are also in need of cleaner alternatives. This presents an exciting and critical opportunity for the UK to develop new lower energy and environmentally safer technology to become global leaders in this industry as well. This would remove the reliance on countries like China for supply of these metals.The need for increasing WEEE recycling and establishing a sophisticated UK industry has been called for in the latest Environmental Audit Committee (EAC) report and securing the supply of REE outside of China, necessary for renewable projects such as the Dogger Bank wind farm, is a priority both at national and European level. These are both issues this research can help solve by recovering and recycling critical metals for a low carbon and circular economy in the UK. DES are exactly the technology to drive this metals recycling revolution in the UK forward.