EXTRACTION OF RHODIUM FROM OTHER PLATINUM-GROUP METALS WITH KELEX-100FROM CHLORIDE MEDIA CONTAINING TIN

Solvent extraction of platinum group metals such as: Pd, Pt and Rh was carried out from chloride media with Kelex 100 in the absence and pre sence of a large amount of tin. When tin is absent in the feed solutio n, the order of extraction was found to be: Pd > Pt > Rh (at low acidi ty) and Pt > Pd > Ph (at high acidity). On the other hand, when a larg e amount of tin is present, the order becomes: Rh > Pd approximate to Pt (at low acidity) and Rh > Pt > Pd (at high acidity). It was found t hat addition of a large amount of tin in the feed solution increases t he Ph extraction and decreases the Pd and Pt extraction, which makes i t possible to separate Rh selectively from their mixed solution. Strip ping of rhodium from the loaded organic solution containing tin can be greatly enhanced by adding some oxidizing agent to the stripping agen t. Stripping increases with the increase in the concentration of the o xidizing agent and the order of the stripping ability of the oxidizing agents employed in this work was found to be: HNO3 > KMnO4 > H2O2. (C ) 1997 Elsevier Science B.V.