Synergistic extraction of gold(I) cyanide with the primary amine Primene JMT and the phosphine oxide Cyanex 921

The extraction of gold(I) from aurocyanide solutions has been studied by means of the synergic mixture of the primary amine Primene JMT and the phosphine oxide Cyanex 921. Different variables that could affect the solvent extraction system were evaluated: equilibration time, temperature, aqueous pH, metal concentration, extractant mixture concentration, organic phase diluent and aqueous ionic strength. The system is selective with respect to the extraction of other metal-cyano complexes. On the basis of the experimental data, treated both graphically and numerically, the extraction mechanism and the stoichiometry of the extracted species were proposed. Stripping of gold from loaded organic phases was also studied using low ionic strength alkaline solutions.