Hirokazu Narita 1, Tomoya Suzuki 1 and Ryuhei Motokawa 2
1 Environmental Management Research Institute, National Institute of Advanced Industrial Science and Technology (AIST)
Most of the refineries for platinum group metals (PGMs) in Japan have adopted solvent extraction methods for mutual separation of PGMs. Few effective extractants for industrial use have been found although some industrial processes were established in 1970's. Recently, some compounds have been reported as candidates for practical PGM extractants in addition to new concepts for PGM extraction mechanisms. In this review article, we present well-known PGM recovery processes based on solvent extraction, industrial extractants and their properties, and conventional extraction mechanism for PGMs. Additionally, we discuss recent interesting extraction systems (amide-type compounds and ionic liquid) and then introduce new extraction concepts based on the specific interactions at the outer-sphere of a metal complex in the organic phase.
platinum group metals, solvent extraction, amide-type extractants, ionic liquids, inner- and outer-sphere interactions
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