Journal of Hazardous Materials, Vol.227, 142-147, 2012
Separation of platinum and rhodium from chloride solutions containing aluminum, magnesium and iron using solvent extraction and precipitation methods
The solvent extraction and precipitation methods have been used to develop a process to separate platinum and rhodium from a synthetic chloride solutions containing other associated metals such as (mg/L): Pt-364, Rh-62, Al-13880, Mg-6980. Fe-1308 at <1 M HCl acidity. At pH 3.4, the quantitative precipitation of Al and Fe was achieved using 10 wt% Na3PO4.12H(2)O, with similar to 4% loss of Pt and Rh due to adsorption phenomenon. The selective separation of platinum was carried out with 0.01 M Aliquat 336 (a quaternary ammonium salt) at an aqueous to organic ratio (A/O) of 3.3 in two stages. Stripping of Pt from loaded organic (LO) at O/A ratio 6 with 0.5 M thiourea (tu) and HCl indicated that similar to 99.9% stripping efficiency. In stripping studies, needle like crystals of Pt were found and identified as tetrakis (thiourea) platinum (II) chloride ([Pt(tu)(4)]Cl-2). The selective precipitation of rhodium was performed with (NH4)(2)S from platinum free raffinate with a recovery of >99%. (C) 2012 Elsevier B.V. All rights reserved.