Anodic Dissolution of Gold in Aqueous Alkaline Cyanide Solutions at Low Overpotentials

Abstract

Potentiodynamic and potentiostatic methods were used to study the anodic dissolution of gold in aqueous alkaline cyanide at low overpotentials (in the region of −0.65 vs. SCE). The effect of cyanide and hydroxide concentration on the anodic dissolution rate at −0.65V vs. SCE was determined from weight loss measurements. The variation of the potential sweep profile with sweep rate and stirring rate was determined and Tafel parameters were measured. The steady‐state gold dissolution was shown to follow the sequence in which the second step is the rate‐determining step. Measurements at sweep rates > 20 mV · sec⁻¹ revealed various aspects of the reaction sequence which helped to reconcile conflicting statements found in the literature regarding the reaction mechanism.