SELECTIVITY ASPECTS OF THE EXTRACTION OF GOLD FROM CYANIDE SOLUTIONS WITH ION-EXCHANGE RESINS

The selectivity of various ion exchange resins for Au(CN)2- and other metallocyanide complexes was studied. The experimental results and the resin structures were compared to attempt to identify the factors that control the selectivity. It was concluded that the hydrophilicity of the polymeric matrix and the ionic density (number of ionic groups per unit volume) play important roles in determining the selectivity characteristics of a resin. A low degree of hydrophilicity and a low ionic density increase the selectivity for gold, while the opposite characteristics favour the loading of base metals, such as iron and copper. A resin with tri-ethyl ammonium groups exhibited selectivity for mono- and bivalent metallocyanide complexes (gold, nickel and zinc) over multivalent ions (iron and copper).