Electron Stoichiometry of Anodic Dissolution of Gold in Aqueous Alkaline Cyanide

Abstract

In an earlier paper (i), it was shown by the use of slow anodic potential sweep measurements that the electrochemical dissolution of gold in de-oxygenated aqueous alkaline cyanide solutions was characterized by the presence of three current peaks.

Electrochemical preparation of potassium gold cyanide

“…Even though the passive film at peak 3 contains trivalent gold, gold still dissolves only in the monovalent state (See current efficiency data in table 2.). This has been pointed out by Pan and Van (1979) and Kirk et al (1979). Our current efficiency data also confirm this.…”

“…Using the observation of Kirk et al (1979) that gold dissolves in potassium cyanide in the monovalent state at potentials less than + 0-4 V (SEE) and the current efficiency data presented here, it is concluded that gold dissolves as aurocyanide at potentials corresponding to second and third peak. Greater than 100,°/o current efficiency observed at -0-6 V is probably due to the additional chemical dissolution.…”

A Potentiodynamic Study of Metals Affecting Precious Metal Recovery from Alkaline Cyanide Solutions

“…A series of oxidation reactions can be seen in the anodic portions of the scans, indicating the dissolution of gold plated during the cathodic scans. The nature of the dissolution reactions has been discussed elsewhere (21)(22)(23)(24)(25)(26). With the addition of 1.0 ppm Pb to the solution (Fig.…”

The anodic behaviour of gold

“…Kirk eta!. (46,47) carried out a large number of carefully controlled coulometric experiments in solutions containing 0.1 M KOH and 0.1 M KCN. They concluded that the electrochemical dissolution of gold in alkaline cyanide is a one-electron transfer reaction throughout the potential range of -0.65 to 0.55 V. At higher potentials, there was evidence of the formation of gold(III) species.…”