Recovery of Platinum from Chloride Leaching Solution of Spent Catalysts by Solvent Extraction

Abstract

Platinum was recovered from the leaching liquor of spent petroleum catalyst by solvent extraction. Most of platinum in the spent catalysts was leached by using a mixture of HCl and H₂O₂ from the roasted spent catalyst. The effect of concentration of HCl/H₂O₂ in the solution, reaction temperature and pulp density was investigated. Complete extraction of Pt and Fe from the leaching liquor was obtained by Aliquat 336 at an O/A ratio of 1 in 2 stages. High purity solutions containing Fe and Pt were obtained from the loaded Aliquat 336 by scrubbing with dilute HCl solution and stripping with HClO₄, respectively. Finally, HCl in the raffinate was regenerated by extraction with TEHA (Tri (2-ethylhexyl) amine) and then by stripping with water. The purity of HCl in the stripped solution was high enough to be reused in the leaching of spent catalysts. The optimum conditions in leaching, extraction and stripping together with the mass balance of the constituents of the spent catalysts in the whole process are reported.