THE EXTRACTION OF GOLD(I) FROM CYANIDE SOLUTIONS BY THE PHOSPHINE-OXIDE-CYANEX-921

The extraction of gold from cyanide solutions by the commercially avai lable phosphine oxide, Cyanex 921, is described. The effect of several variables, such as equilibration time, temperature, diluent aromatici ty, extractant concentration and the ionic strength of the aqueous pha se is discussed. An IR spectroscopy study showed that the Au (CN)2- co mplex 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 solutio ns. Stripping was accomplished by low ionic strength aqueous solutions and enhanced by high temperatures.