Electrochemical study of silver telluride (Ag2Te): anodic and cathodic potential dependent-reactions in alkaline cyanide solutions

• Published in: Hydrometallurgy 2019-01, Vol.183, p.230-239
• Main Authors: González-Ibarra, A.A., Nava-Alonso, F., Uribe-Salas, A.
• Format: Article
• Language: English
• Subjects: Carbon paste electrode; Cyanide solutions; Cyclic voltammetry; Electrochemical reaction; Silver telluride
• ISSN: 0304-386X; 1879-1158
• DOI: 10.1016/j.hydromet.2018.12.019

Although electrochemical characterization has been used to elucidate the species formed during hydrometallurgical processes, it has not been commonly applied to the cyanidation of precious metal tellurides. In this study, voltammetric characterization of the silver telluride (Ag2Te) reaction system in alkaline cyanide solutions (pH 10.9 and 1250 mg/L CN−) was carried out making use of carbon paste electrodes. For this purpose, the electrochemical reactions system of elemental silver and elemental tellurium were first studied by cyclic voltammetry in two aqueous media (i.e., aqueous solution at pH 10.9, and 1250 mg/L CN− at pH 10.9) and, by comparing the cyclic voltammograms obtained with those for Ag2Te, the electrochemical reaction system was elucidated. The results obtained showed that the anodic oxidation of Ag2Te in alkaline cyanide solutions occurred by at least two consecutive steps according to: Step 1 (fast reaction): Ag2Te + 4CN− ↔ Te + 2Ag(CN)2− + 2e−. Step 2 (slow reaction): Te + 3H2O ↔ TeO32− + 6H+ + 4e− while the cathodic reduction of Ag2Te in alkaline cyanide solutions occurred according to:Ag2Te+2e−↔2Ag+Te2− •Anodic and cathodic potential dependent-reactions of Ag2Te were investigated.•Carbon paste electrodes in alkaline cyanide solutions were used.•The anodic oxidation of Ag2Te occurred in at least two consecutive steps.•The cathodic reduction of Ag2Te produced elemental silver and released Te2−.•SEM-EDS results support electrochemical results.