Cyanide recovery from gold extraction process waste effluents by ion exchange I.: Equilibrium and kinetics

The use of an ion exchange resin in the recovery of copper cyanide complexes from wastewater and the recycling of the cyanide used in cyanidation to the gold cyanidation step is an economically interesting process. The equilibrium and kinetics in the loading stage using a strong base resin, Bayer Lewatit MP500, have been studied in this work. Two theoretical models were applied to the interpretation of these data. Experimental data on copper concentration were fitted to well known models. The constant separation factor isotherm was used to fit the equilibrium results, high values of the equilibrium constants being obtained at different pH. Two theoretical models were applied. Both the film mass transfer and the pore diffusion models give good fitting of the experimental results providing K-f and D-p for different pH. The Helfferich criteria allowed to establish control of the process in the liquid film surrounding the resin particles.