ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Electrochemical behavior of silver during cyanidation in the presence of sulfide minerals

M. Mikali, A. Barbouchi, R. Idouhli, A. Abouelfida, A. Yaacoubi, I. Benzakour, H. Faqir, A. Boulaamail, and A. Bacaoui

Applied Chemistry and Biomass Laboratory, Department of Chemistry, Cadi Ayyad University, Marrakesh, Morocco

E-mail: m.mikali@managemgroup.com

Received: 31 August 2022  Accepted: 30 November 2022

Abstract:

The present work focuses mainly on the study of electrochemical phenomena induced by the presence of sulfide minerals during silver cyanidation. Firstly, an electrochemical study was carried out to characterize the electrochemical behavior of silver electrode in cyanide solution. The obtained results were useful to explain the mechanism of silver dissolution by cyanidation. Secondly, the effect of oxidants type and cyanide concentrations was carried out in order to identify optimal conditions for silver dissolution. Based on the obtained results, cyanidation tests were carried out in the absence and in the presence of sulfide minerals (chalcopyrite, sphalerite and galena). The results obtained by electrochemical methods (Open circuit potential, polarization curves, cyclic voltammetry, Tafel curves), complemented with scanning electron microscope (SEM) examination coupled with energy-dispersive X-ray spectroscopy (EDX), reveal that the limitation of silver cyanidation can be attributed to several factors. Passivation phenomenon occurs in the presence of galena, while galvanic interaction takes place in the presence of sphalerite. Chalcopyrite displays different impacts through liberated copper ions that overconsume available free cyanide. According to this study, impact of sulfide minerals on silver dissolution varies in the following order: chalcopyrite > galena > sphalerite.

Keywords: Silver cyanidation; Sulfide minerals; Passivation; Galvanic interaction; Electrochemical methods

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-022-02613-2

Chemical Papers 77 (4) 2103–2113 (2023)