The platinum group metals (PGMs) are traditionally separated from one another and the other metals by a complex series of selective precipitation techniques. 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. Adding SnCl2 to a Rh feed is a good procedure which can be used to make Rh react more easily to extraction.
In the present study, the effect of addition of SnCl2 on the solvent extraction behaviour of Rh was discussed. The extraction efficiency of Rh increased with increasing the molar ratio of [Sn]:[Rh] and the stripping efficiency of Rh from organic phase by nitric acid solution was better than that by sulfuric acid solution. When the molar ratio of [Sn]:[Rh] increased, the stripping efficiency of Rh became better. The extraction mechanism of Rh from hydrochloric acid solutions containing SnCl2 was also discussed and the following extraction reaction was considered.
3R3No+4H+a+Rh(SnCl3)54-, a=(R3NH)3RhH(SnCl3)5, o
