Cyanide recovery by ion exchange from gold ore waste effluents containing copper

The recovery of cyanide from waste effluents of the cyanidation process in gold extraction plants is important environmentally and economically. In this respect ion exchange is being tested as a possible economic and versatile method for gold ores containing copper minerals. The present study shows the potential of strong and weak base ion exchange resins, particularly the former, for separating copper cyanide complexes from these industrial effluents, and in particular the feasibility of elution with different eluants. Three possible reagents are proposed for use with these resins and the industrial effluents as load solutions: NaCN, NaSCN and NaNO3. The recovery of copper complexes from industrial effluents using a strong base resin, Lewatit MP-500, and NaSCN as eluant solution, is very high, with recoveries of over 90% in each step. Problems arise when several cycles of load and elution are carried out with the resin, and the performance of the resin decreases when working with unfiltered solutions after several operational cycles.