Co-deposition of copper in trans-dichlorodiaminepalladium salt

Описание

Тип публикации: статья из журнала

Год издания: 2019

Идентификатор DOI: 10.17580/tsm.2019.09.03

Ключевые слова: Ammonia solution, Copper, Deposition, Dichlorodiaminepalladium, Hydrochloric acid, Nucleation, Palladium

Аннотация: In palladium refining, the trans-dichlorodiaminepalladium salt serves as the basic compound for selective extraction of palladium from complex solutions. The final salt of trans-[Pd(NH3)2Cl2], which is then used to produce refined metallic palladium, is subjected to hydrochloric acid deposition from ammonia solution containing non-Показать полностьюferrous metal impurities. Copper is the dominant impurity in refined palladium. This research aimed to understand the process of co-deposition of copper with dichlorodiaminepalladium. Copper (I) and (II) chlorides were introduced in the ammonia solution of palladium salt [Pd(NH3)4]Cl2. Dichlorodiaminepalladium was then deposited from the solution, and the salt that formed was analysed for copper content. It is shown that due to the poorly soluble compound of CuCl being formed in acid media it is copper (I) that predominantly gets deposited with dichlorodiaminepalladium. Prior oxidation of the ammonia solution leads to a significantly reduced copper concentration in the deposited salt as CuCl2 is highly soluble. It is demonstrated that as the concentration of copper in the solution goes down from 0.72 to 0.125 g/l, a reduction in the copper concentration in dichlorodiaminepalladium is observed (from 0.008 to 0.001%). Through a drastic change in the salt deposition conditions, it was clearly shown that both the absorption mechanism of copper co-deposition in trans-[Pd(NH3)2Cl2] and occlusion are auxiliary. It was established that, in hydrochloric acid processing of ammonia solutions containing palladium and copper, once pH has reached 5-7 what precipitates first is copper in the form of poorly soluble hydroxide Cu(OH)2 and maybe also hydroxochloride. pH ~ 5 launches large-scale deposition of dichlorodiaminepalladium. Cu(OH)2 particles serve as salt nuclei helping [Pd(NH3)2Cl2] nucleation. As a result, the Cu(OH)2 microparticles find themselves in the cores of the dichlorodiam inepalladium cr ystals, so there are no conditions to enable the dissolution of copper hydroxides even at the final pH of 1.0. The salt deposition conditions were changed to prove that copper co-deposition with dichlorodiaminepalladium is mainly caused by the nonisomorphic i nclusions of Cu(OH)2 in the trans-[Pd(NH3)2Cl2] crystals. © 2019, "Ore and Metals" Publishing house. All rights reserved.

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Издание

Журнал: Tsvetnye Metally

Выпуск журнала: Vol. 2019, Is. 9

Номера страниц: 22-26

ISSN журнала: 03722929

Издатель: "Ore and Metals" Publishing house

Авторы

  • Ryumin A.I. (Department of Non-Ferrous Metallurgy, Siberian Federal University, Krasnoyarsk, Russian Federation)
  • Belousov O.V. (Department of Non-Ferrous Metallurgy, Siberian Federal University, Krasnoyarsk, Russian Federation)
  • Sorkinova G.A. (Department of Non-Ferrous Metallurgy, Siberian Federal University, Krasnoyarsk, Russian Federation)
  • Sirotina D.Y. (Siberian Federal University, Krasnoyarsk, Russian Federation)

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