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 tha t control the selectivity. It was concluded that the hydrophilicity of the polymeric matrix and the ionic density (number of ionic groups pe r unit volume) play important roles in determining the selectivity cha racteristics of a resin. A low degree of hydrophilicity and a low ioni c density increase the selectivity for gold, while the opposite charac teristics 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 mu ltivalent ions (iron and copper).