Recovery and Purification of Iridium from Secondary Resources: A Review

摘要

Abstract Iridium is widely used in high-temperature corrosion protection, catalytic oxidation, and electroluminescence owing to its excellent catalytic activity, corrosion, and oxidation resistance at high temperatures. Considering the high value of iridium-containing secondary resources, scarcity of iridium, and low recovery yield, it is important to enhance the ability to recover and purify iridium-containing materials. This paper provides an overview of the critical aspects of the high-purity iridium recovery process, including pretreatment, dissolution, and purification processes for iridium-containing materials. Given the difficult iridium dissolution, five effective dissolution methods including alloy fragmentation, molten acid leaching, molten salt chlorination, pressurized chlorination, and electrochemical dissolution are listed in detail to achieve the prerequisite of iridium extraction. For the further purification of iridium, precipitation purification, solvent extraction, and ion exchange are summarized. Notably, the factors affecting the purity and yield of iridium recovery in the precipitation purification process are analyzed in focus, which provides an important theoretical basis for realizing high-efficiency iridium purification. In addition, the extraction effects of different solvent extraction systems in the extraction purification process are compared in favor of an efficient extraction system. These results are expected to provide input for the establishment of an integrated high-purity iridium recovery system.Graphical Abstract