Gold Recovery from Nickel Catalyzed Ammonium Thiosulfate Solution by Strongly Basic Anion Exchange Resin

Abstract

Copper catalyzed ammonium thiosulfate leaching process has been proposed as an alternative gold extraction process to cyanidation. In order to recover gold from the ammonium thiosulfate solution, ion exchange process has been proposed as a gold recovery method using strongly basic anion exchange resin. However, the co-adsorption of copper along with gold causes difficulty in separating gold and copper at the gold elution stage. Our previous study has demonstrated that nickel catalyzed ammonium thiosulfate solution for gold extraction has the advantage of reducing thiosulfate consumption. In this study, the results also demonstrated the advantage of gold recovery from the nickel catalyzed ammonium thiosulfate solution by strongly basic anion exchange resin. The optimal gold loading conditions on a 1 g/dm³ strongly base anion exchange resin (wet base value) are investigated in several ion concentrations and 95 kg-Au/t-resin has been obtained. The alternative gold eluant was investigated as the gold loaded resin cannot be eluted by conventional hydrochloric acid. Results showed that the elution efficiency was in the order of OH⁻ < Cl⁻ << NO₃⁻ < Br⁻ << I⁻ < ClO₄⁻. The maximum gold recovery by using 2.5 mol/dm³ ClO₄⁻ was around 98% with the stripped resin assayed as 0.2 kg/t Au. The feasibility of resin recycling has demonstrated that there was no deterioration in gold adsorption and desorption for four cycles.