Selective precipitation of ammonium hexachloropalladate from leaching solutions of cemented palladium with zinc

Nguyen, Viet-NhanHoa; Song, Si Jeong; Lee, M.S.

doi:10.2298/jmmb220208013n

Cited by 2 publications

(1 citation statement)

References 22 publications

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“…Other methods that are often used to process post-elution solutions are reduction (using hydrazine hydrate, sodium borohydride, ascorbic acid, oxalic acid, and formic acid as reducing agents [38][39][40]), and precipitation (using NaOH, NH 3 , and NH 4 Cl as precipitating agents [41,42]). Refining processes often combine different methods (extraction, reduction, cementation, precipitation) to obtain high-purity compounds of specific precious metals.…”

Section: Introductionmentioning

confidence: 99%

Precipitation of Precious Metals Concentrates from Post-Elution Solutions from Ion-Exchange Processes

Goc,

Kluczka,

Benke

et al. 2024

Minerals

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Precious metals have long been considered as critical raw materials in many countries. There is a growing emphasis on recovering these metals from secondary sources such as automotive catalysts or WEEE (waste of electrical and electronic equipment). During the leaching process of these materials, solutions with low concentrations of precious metals are obtained, which necessitates the use of ion-exchange methods. Following sorption and elution, a post-elution solution called eluate is produced, containing precious metals and no impurities. This eluate must undergo further processing to obtain pure metals or its compounds. The objective of this study was to explore the feasibility of recovering precious metals from post-elution solutions through cementation, reduction, precipitation, or refining techniques. The analysis of the research results indicated that metallic zinc powder is the most effective cementing agent for platinum, palladium, rhodium, and gold. Metallic aluminum and copper powders can selectively cement gold and palladium, separating them from platinum and rhodium. Aqueous hydrazine hydrate solution is the best-reducing agent for precious metals, while an aqueous hydrogen peroxide solution can selectively reduce platinum and palladium, separating them from gold and rhodium.

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Section: Introductionmentioning

confidence: 99%

Precipitation of Precious Metals Concentrates from Post-Elution Solutions from Ion-Exchange Processes

Goc,

Kluczka,

Benke

et al. 2024

Minerals

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Evaluation of Adsorption Ability of Lewatit® VP OC 1065 and Diaion™ CR20 Ion Exchangers for Heavy Metals with Particular Consideration of Palladium(II) and Copper(II)

Wołowicz,

Hubicki

2024

Molecules

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The adsorption capacities of ion exchangers with the primary amine (Lewatit® VP OC 1065) and polyamine (Diaion™ CR20) functional groups relative to Pd(II) and Cu(II) ions were tested in a batch system, taking into account the influence of the acid concentration (HCl: 0.1–6 mol/L; HCl-HNO3: 0.9–0.1 mol/L HCl—0.1–0.9 mol/L HNO3), phase contact time (1–240 min), initial concentration (10–1000 mg/L), agitation speed (120–180 rpm), bead size (0.385–1.2 mm), and temperature (293–333 K), as well as in a column system where the variable operating parameters were HCl and HNO3 concentrations. There were used the pseudo-first order, pseudo-second order, and intraparticle diffusion models to describe the kinetic studies and the Langmuir and Freundlich isotherm models to describe the equilibrium data to obtain better knowledge about the adsorption mechanism. The physicochemical properties of the ion exchangers were characterized by the nitrogen adsorption/desorption analyses, CHNS analysis, Fourier transform infrared spectroscopy, the sieve analysis, and points of zero charge measurements. As it was found, Lewatit® VP OC 1065 exhibited a better ability to remove Pd(II) than Diaion™ CR20, and the adsorption ability series for heavy metals was as follows: Pd(II) >> Zn(II) ≈ Ni(II) >> Cu(II). The optimal experimental conditions for Pd(II) sorption were 0.1 mol/L HCl, agitation speed 180 rpm, temperature 293 K, and bead size fraction 0.43 mm ≤ f3 < 0.6 mm for Diaion™ CR20 and 0.315–1.25 mm for Lewatit® VP OC 1065. The maximum adsorption capacities were 289.68 mg/g for Lewatit® VP OC 1065 and 208.20 mg/g for Diaion™ CR20. The greatest adsorption ability of Lewatit® VP OC 1065 for Pd(II) was also demonstrated in the column studies. The working ion exchange in the 0.1 mol/L HCl system was 0.1050 g/mL, much higher compared to Diaion™ CR20 (0.0545 g/mL). The best desorption yields of %D1 = 23.77% for Diaion™ CR20 and 33.57% for Lewatit® VP OC 1065 were obtained using the 2 mol/L NH3·H2O solution.

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Selective precipitation of ammonium hexachloropalladate from leaching solutions of cemented palladium with zinc

Cited by 2 publications

References 22 publications

Precipitation of Precious Metals Concentrates from Post-Elution Solutions from Ion-Exchange Processes

Precipitation of Precious Metals Concentrates from Post-Elution Solutions from Ion-Exchange Processes

Evaluation of Adsorption Ability of Lewatit® VP OC 1065 and Diaion™ CR20 Ion Exchangers for Heavy Metals with Particular Consideration of Palladium(II) and Copper(II)

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