Abstract
Abstract
 
 The hydrometallurgical method was used to platinum and palladium leaching with aqua regia solution (3HCl: HNO3). The leaching experiments were designed to obtain the optimum conditions by using Taguchi method with 16 experiments at three different factors (time, temperature and solid to liquid ratio), and each factor has four different levels. In this study, leaching the powder sample of catalytic converter that contains platinum and palladium was conducted on the basis of the formation of chloro complexes platinum and palladium (PtCl62-, PdCl42-) with different concentrations in the acidic solution. The optimum conditions for leaching process are (time = 120 minutes, temperature = 100°C, and solid to liquid ratio = 1/20).The best efficiency for platinum and palladium leaching at these conditions were 97.58%, 93.23%, respectively. After leaching process at optimum conditions, platinum was firstly precipitated in the form of (NH4)2PtCl6 (ammonium chloroplatinate) by adding (5ml/l) of ammonium chloride (NH4Cl) as a precipitant agent .Then, palladium was precipitated in the form of (NH4)2PdClO3 (palladium ammonium chlorate) by adding (5g/l) of sodium chlorate (NaClO3) as a precipitant agent to the remaining solution after the removal of platinum. The best efficiency for platinum and palladium recovery at optimum leaching conditions were 91.94%, and 98.82%, respectively.
 
 Keywords: Aqua regia, catalytic converter, PGMs, Platinum, Palladium, recovery, catalytic converter, 3HCl:HNO3.
Highlights
Commitment to the European standards to keep pollution-free environment, all cars manufactured after 1993 should be equipped with catalytic converter
Catalytic converters Contain precious metals like Pt, Pd and Rh, which work on the oxidation (CO), and (HC), and the reduction of (NOx) to lower the required levels of emissions [1].The formation of catalytic converter carrier vary depending upon engine capacity and kind of used fuels [2].Recovery of platinum group metals from secondary sources was an important mean of making materials economically in addition to environmental considerations
About 125,000 kg of platinum, palladium, and rhodium was recovered around the world from new and old scrap in 2015; 55,000 kg was recovered from spent catalytic converters in the United States. 25% of Palladium replaced platinum because it is less expensive in most gasoline engines catalytic converters, the proportion can be as much as 50% in some applications [6].The carrier is made up of a ceramic or metallic substances as shown in Mohammed Qasim Hammadi Al-Khwarizmi Engineering Journal, Vol 13, No 3, P.P. 131- 141 (2017)
Summary
Commitment to the European standards to keep pollution-free environment, all cars manufactured after 1993 should be equipped with catalytic converter. About 125,000 kg of platinum, palladium, and rhodium was recovered around the world from new and old scrap in 2015; 55,000 kg was recovered from spent catalytic converters in the United States. 25% of Palladium replaced platinum because it is less expensive in most gasoline engines catalytic converters, the proportion can be as much as 50% in some applications [6].The carrier is made up of a ceramic or metallic substances as shown in Mohammed Qasim Hammadi Al-Khwarizmi Engineering Journal, Vol 13, No 3, P.P. 131- 141 (2017). The proportion of platinum to palladium depends on the level of emission control, metals prices, and the type of car. Platinum is used in catalytic converters for diesel engines, while platinum and palladium are used in vehicles powered by gasoline [9]
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