Investigation of Factors Affecting the Kinetics of Gold Heap Leaching

The present study investigates the influence of reagent concentrations and the presence of impurities on the kinetics of gold heap leaching. Of particular note is the focus on the role of cyanide concentration and the effects of metallic impurities in the leach solution. The analytical results obtained confirmed the presence of accompanying metals, including copper, iron, zinc, and lead, in the productive solution. These metals have the capacity to form complexes with cyanide, thus competing with gold for the reagent and potentially affecting the efficiency of the leaching process. The experimental data demonstrated that, at comparatively low concentrations of sodium cyanide, the dissolution rate of gold is directly proportional to the cyanide concentration. However, as the cyanide concentration increases beyond a certain threshold, the rate of gold dissolution becomes limited by the availability of dissolved oxygen. This shift in rate-controlling mechanisms underscores the dual importance of both cyanide and oxygen in optimizing gold recovery. It was further established that maintaining a minimum sodium cyanide concentration of 80 mg/l in the productive solution is essential for ensuring a consistent leaching rate and for preventing the accumulation of metallic impurities that can interfere with downstream processes, including gold precipitation.