The extraction of gold(I) from cyanide solutions by the phosphine oxide Cyanex 921

The extraction of gold from cyanide solutions by the commercially available phosphine oxide, Cyanex 921, is described. The effect of several variables, such as equilibration time, temperature, diluent aromaticity, extractant concentration and the ionic strength of the aqueous phase is discussed. An IR spectroscopy study showed that the Au (CN)2− complex and the extractant did not form a discrete compound, supporting a solvating mechanism of extraction. Results showed that the phosphine oxide could effectively extract gold(I) cyanide from alkaline solutions. Stripping was accomplished by low ionic strength aqueous solutions and enhanced by high temperatures.The authors would like to thank the DGICYT, Spain, for financial support of Project PB89-0021. Also, thanks to Mrs. M.I. Cuenca for assistance in the work.Peer reviewe