Clean and Zero Emission Processes for Chemical Extraction of Critical and Precious Metals with Deep Eutectic Solvents

化学提取金属的常规方法一般已被采矿业用于从初级（例如矿石）和次级（即寿命终止产品）资源中回收金属。无机酸和有机萃取剂是金属萃取常用的化学剂。随着金属需求的增长，使用湿法冶金回收金属具有重要意义，这主要是由于我们社会的电气化革命。近年来，一种新型的金属萃取介质被称为深共晶溶剂（DES）。DES具有与离子液体相似的性能，但具有成本低、对环境影响小、易于合成的优点，适合在采矿和金属提取作业中大规模生产。最近才引入的DES已经发现了一些非常有趣的应用，从一次和二次资源的金属提取过程中，然而，关于这一主题的文献有限。亲水DES可用于金属的浸出，在替代无机酸和减少金属提取过程中的水消耗方面具有很大的潜力。利用DES从矿物或废物中高效、选择性地浸出金属是可行的，但其浸出动力学和理化性质仍然限制了其大规模应用。从DES中进行电化学回收也是可行的，但需要进一步研究。另一方面，疏水DES可用于从水溶液中回收金属，例如，对于溶剂萃取金属，疏水DES是可靠的替代离子液体。在这个提议中，我们的目标是探索亲水性和疏水性DES用于从一次和二次来源中提取和回收金属。在第一部分的工作中，我们将重点研究DES的合成和表征，并对其进行优化，以用于金属的提取和回收。我们感兴趣的金属包括镍、钴、锂、稀土元素、金和铜。在后期，将探索优化的DES系统，用于从一次和二次资源中提取和回收上述金属。该研究计划的长期目标是开发基于新型DES系统的可靠金属提取工艺，并对该工艺的化学性质有全面的了解。在长远计划内，我们会界定污水排放系统的环境及经济效益。在接下来的五年中，我们将设计和尝试不同的DES系统用于金属提取，使用故障快速设计系统。DES金属提取系统具有强大的潜力，可以在我们从资源材料中提取金属的方式上进行革命，大大降低水的消耗和有毒试剂的使用。本项目将培养博士生2名，硕士生4名。

The conventional methods for chemical extraction of metals have generally been used by the mining industry for the recovery of metals from primary (e.g. ores) and secondary (i.e. end-of-life products) resources. The mineral acids and organic extractants are the common choice of chemicals for metals extraction. The recovery of metals using hydrometallurgy is of major importance with the growth in metal demand, largely due to electrification revolution in our societies. In recent years, a novel medium for metal extraction, known as deep eutectic solvents (DES), has been introduced. DES carry similar properties to ionic liquids but with additional advantages of low cost, far less environmental impact, and easy synthesis processes for their production in large scale in mining and metals extraction operations. Introduced only very recently, DES have found some very interesting applications in metals extraction processes from primary and secondary resources, however a limited literature is available on this topic. Hydrophilic DES can be used for leaching of metals and have great potential to replace mineral acids, and to reduce water consumption in metals extraction processes. Efficient and selective leaching of metals from minerals or wastes is feasible by using DES. However, the kinetics of leaching as well as the physicochemical properties of DES are still limiting their large-scale application. Electrochemical recovery from DES is also possible but deserves further investigation. On the other hand, hydrophobic DES can be used to recover metals from aqueous solutions e.g., for the solvent extraction of metals, hydrophobic DES constitute credible alternative ionic liquids. In this proposal, we aim to explore hydrophilic and hydrophobic DES for the extraction and recovery of metals from primary and secondary sources. In the first part of work, we will focus on the synthesis and characterization of DES and optimize them for the extraction and recovery of metals. The metals of our interest include nickel, cobalt, lithium, rare earths elements, gold and copper. In the later stage, the optimized DES systems will be explored for the extraction and recovery of the said metals from primary and secondary resources. The long-term goals of this research program are to develop robust metals extraction processes based on novel DES systems and build a comprehensive understanding of the chemistry of the process. Within a long-term plan we will define the environmental and economic benefits of the DES systems. During the next five years, we will design and try different DES systems for metals extraction, using the fail-fast design system. The DES metals extraction systems have the strong potential to make a revolution in the way we extract metals from the resource materials, substantially lowering the water consumption and use of toxic reagents. Two Ph.D. students and four Master's students will be trained through this research program.