Electrochimica Acta, Vol.41, No.6, 879-885, 1996
The Electrochemical Oxidation of Gold Telluride (AuTe2) in Perchloric-Acid Solutions
Although gold tellurides are important sources of gold in several areas in the world, little attention has been paid to understanding how they might be processed. This paper describes an electrochemical study of the oxidation of one gold telluride, namely calaverite (AuTe2) in acid solution. The principal technique in this study was cyclic voltammetry. Up to a potential of 0.5 V (sce), the reaction products are gold metal and HTeO2+, as is predicted from the E-pH diagram. At potentials above 0.75 V (sce), the reaction products are gold metal and solid tellurous acid which partially passivates the calaverite surface. Tellurous acid is soluble in 1.0 M perchloric acid, being thermodynamically unstable. Under appropriate conditions an oscillating electrochemical reaction is observed. At lower pHs (up to about 2), the telluryl ion is observed. Above this pH, up to about 3, tellurous acid and gold are the preferred products.