title: Oxidative leaching process with cupric ion in hydrochloric acid media for recovery of Pd and Rh from spent catalytic converters.
abstract: The recycling of platinum-group metals from wastes such as autocatalytic converters is getting growing attention due to the scarcity of these precious metals and the market pressure originated by increase of demand in current and emerging applications. Hydrometallurgical treatment of such wastes is an alternative way to the most usual pyrometallurgical processes based on smelter operations. This paper focuses on the development of a leaching process using cupric chloride as oxidising agent, in HCl media, for recovery of palladium and rhodium from a spent catalyst. The chloride media allows the adequate conditions for oxidising and solubilising the metals, as demonstrated by equilibrium calculations based on thermodynamic data. The experimental study of the leaching process revealed that Pd solubilisation is clearly easier than that of Rh. The factors temperature, time, and HCl and Cu(2+) concentrations were significant regarding Pd and Rh leaching, the latter requiring higher factor values to achieve the same results. Leaching yields of 95% Pd and 86% Rh were achieved under optimised conditions (T = 80 °C, t = 4h, [HCl] = 6M, [Cu(2+)] = 0.3M).
authors: Laboratório Nacional de Energia e Geologia, I.P., Campus do Lumiar, 1649-038 Lisboa, Portugal. Electronic address: carlos.nogueira@lneg.pt.
authors: C A
authors: CA
authors: Nogueira
authors: Centro de Química e Bioquímica, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade de Lisboa, 1749-016 Lisboa, Portugal. Electronic address: appaiva@fc.ul.pt.
authors: A P
authors: AP
authors: Paiva
authors: Laboratório Nacional de Energia e Geologia, I.P., Campus do Lumiar, 1649-038 Lisboa, Portugal.
authors: P C
authors: PC
authors: Oliveira
authors: Centro de Ciências do Mar, Departamento de Química e Farmácia, Faculdade de Ciências e de Tecnologia, Campus de Gambelas, 8005-139 Faro, Portugal. Electronic address: mcorada@ualg.pt.
authors: M C
authors: MC
authors: Costa
authors: Centro de Investigação em Química do Algarve, Departamento de Química e Farmácia, Faculdade de Ciências e de Tecnologia, Campus de Gambelas, 8005-139 Faro, Portugal. Electronic address: amcosta@ualg.pt.
authors: A M Rosa
authors: AM
authors: da Costa
mesh_terms: D001336:Automobiles; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D006851:Hydrochloric Acid / Q000737:chemistry*; D010084:Oxidation-Reduction; D010165:Palladium / Q000737:chemistry*; D059027:Recycling / Q000379:methods; D012238:Rhodium / Q000737:chemistry*; D013696:Temperature; D014866:Waste Products
chemical_list: D014866:Waste Products; D010165:Palladium; D003300:Copper; D012238:Rhodium; D006851:Hydrochloric Acid; C029892:cupric chloride
keywords: Cupric chloride; Hydrometallurgy; Oxidative leaching; Pd–Rh catalyst; Recycling