Gold recovery from chloride leaching solutions by electrodeposition-redox replacement method

Currently, the adsorption methods (e.g., CIP / CIL) are by far dominating the recovery of gold from leaching solutions, especially in cyanide media. However, gradual shift towards cyanide-free gold processes also requires new developments in the recovery technologies. High concentrations of base metal and impurities cause co-adsorption by activated carbon or ion exchange resins and consequently lower gold recovery. As an alternative solution, the electrodeposition-redox replacement (EDRR) method was recently demonstrated for recovery of gold from synthetic chloride solutions. In contrast to adsorption, EDRR does not require addition of chemicals in the process and is suitable for elemental gold recovery from chloride leaching solution. In this paper, cupric chloride solution from ore leaching was tested for applicability of the EDRR method. Obtained results demonstrate that gold can be recovered from industrial process solutions containing Au at ppm scale while the base metal (Cu) concentration was as high as 30 g/L and other impurities (mainly Fe, also Zn, Co and Ni) present at various levels between ppm and g/L. The final gold deposit was analyzed with scanning electron microscopy, which confirmed the recovery of gold from the solution. Further optimization of the EDRR process parameters could make it a viable alternative to existing best available technologies due to simplicity of the process flowsheet, energy efficiency and ability for selective recovery of elemental gold even from very low concentrations.