Solvent Extraction Characteristics of Ruthenium from Chloride Solutions added Tin(II) with TOA and TOMAC

Abstract

Chloride is one of the effective medium in which platinum group metals (PGMs) can be brought into a solution, thus chlorocomplexes are particularly important in the process chemistry of PGMs separations. Ru(III) chlorocomplexes are poorly extracted into organic solvents, which is due to the charge of the complex as well as those inert character in a solution, that is, formation of RuCl6–n(H2O)n (n = 1–6). The problem of solvent extraction of Ru from chloride solutions has not yet been solved and there is no effective industrial extractant for Ru. PGMs are traditionally separated from one another and the other metals by a complex series of selective precipitation techniques and distillation. These are generally inefficient in terms of the degree of separation achieved. Solvent extraction applied to refining process for PGMs offers several advantages over the traditional precipitation methods and distillation. Adding Sn(II) to a Rh(III) feed is a good procedure which can be used to make Rh react more easily to extraction. However, the effect of addition of Sn(II) on extraction of Ru(III) from chloride solution is not clarified. In the present study, the extraction of Ru from hydrochloric acid solutions with tri-n-octylamine (TOA) and trioctyl methyl ammonium chloride (TOMAC) were tested to clarify the effect of addition of Sn(II) on the extraction of Ru and stripping of Ru. The addition of Sn(II) was effective for the extraction of Ru, however, the stripping effeciency of Ru was not sufficient.