ABSTRACT

Increasing applications of precious metals (PMs: Au, Ag and platinum group metals) and the growing demand is a matter of great concern for supply security. The hydrometallurgical route through chloride-based leaching has been considered as the most promising method to recover almost all the metals. However, separation of metal-chloro complexes formed during the leaching is difficult to achieve because of similar properties of these complexes. Among the methods developed to extract and separate the metal-chloro complexes, ionic liquid (IL)-based solvent extraction has been recognized as one of the most promising approaches. The ionic liquids possess unique characteristics of ‘greener,’ ‘designer’ and ‘highly effective’ solvents. This paper reviews extraction and separation of PM-chloro complexes by ionic liquids. Mechanisms and IL role in the process, along with merits and drawbacks of IL-assisted solvent extraction are discussed comprehensively. Effects of operational conditions, stripping, and regeneration of the loaded ILs and possible use of ionic liquids in other separation methods are also presented. A flow-sheet for separation of PM-chloro complexes has been developed as a part of basic process approach using ionic liquids. In addition, future directions for the development and application of IL-assisted solvent extraction in separation of precious metals are provided.

摘要

贵金属（PMs：金、银和铂族金属）的应用不断增加，需求不断增长，是供应安全备受关注的问题。通过氯化物浸出的湿法冶金路线被认为是回收几乎所有金属的最有前途的方法。然而，由于这些络合物的性质相似，浸出过程中形成的金属-氯络合物的分离很难实现。在提取和分离金属氯络合物的方法中，基于离子液体（IL）的溶剂萃取已被认为是最有前途的方法之一。离子液体具有“更环保”、“设计”和“高效”溶剂的独特特性。本文综述了离子液体对PM-氯配合物的萃取和分离。全面讨论了 IL 辅助溶剂萃取的机理和 IL 在该过程中的作用，以及 IL 辅助溶剂萃取的优点和缺点。还介绍了操作条件、汽提和负载离子液体再生的影响以及离子液体在其他分离方法中的可能使用。作为使用离子液体的基本工艺方法的一部分，开发了用于分离 PM-氯配合物的流程图。此外，还为离子液体辅助溶剂萃取在贵金属分离中的开发和应用提供了未来方向。作为使用离子液体的基本工艺方法的一部分，开发了用于分离 PM-氯配合物的流程图。此外，还为离子液体辅助溶剂萃取在贵金属分离中的开发和应用提供了未来方向。作为使用离子液体的基本工艺方法的一部分，开发了用于分离 PM-氯配合物的流程图。此外，还为离子液体辅助溶剂萃取在贵金属分离中的开发和应用提供了未来方向。