Книга: Liquid-Liquid Extraction: of Tetravalent Platinum

The high prices of precious metals like platinum group metals (PGM?s) have ensured that there is continued interest in the development of new extractants for the commercial concentration and separation of these metals. The PGM?s platinum, palladium, rhodium, iridium, osmium and ruthenium together with silver, and gold generally occur in nature with the major base metals like iron, copper, nickel and cobalt and wide range of minor elements such as lead, tellurium, selenium and arsenic and both technical and commercial considerations demand that the indusial PGM?s be separated from the other metals and each other to high purity, with high yield and with a high percentage recovery. Liquid- liquid extraction (LLE), also called solvent extraction (SX), is a process that allows the separation of two or more components due to their unequal solubility?s in two immiscible liquid phases. In LLE processes, there are many cases both in analytical and industrial chemistry where the main objective of separation is achieved by extraction using a chemical extractant. In analytical and separation science, this method enjoys a favored position among separation techniques because of its simplicity.