A comparative study of electrodeposition and sodium dithionite reduction for recovering gold in gold-rich solution from the adsorption of thiosulfate solution by ion exchange resin

A comparative study was performed on electrodeposition and sodium dithionite reduction for recovering gold in the gold-rich solution from the adsorption of thiosulfate solution by ion exchange resin. Using electrodeposition method, gold started to deposit when the potential was lower than -100 mVHg/HgO. The rise of Cl- concentration improved gold deposition while the increases of SO32- and S2O32- concentrations were unbeneficial to gold deposition. When the solution was deposited at the optimum potential of -600 mVHg/HgO for 5 h, the gold deposition percentage reached 99.33 %. With sodium dithionite reduction method, the gold reduction percentage achieved 100 % after only 5 min as S2O42-dosage was eight times of the theoretical amount. The increases of SO32- and S2O32- concentrations hindered gold reduction while the augment of Cl- concentration had no obvious effect. Overall, sodium dithionite reduction method has the advantages of shorter reaction time, higher gold recovery percentage, better solution stability and lower recovery cost, and thus it has a broader industrial application prospect.