Effect of silver, nickel and copper cyanides on gold adsorption on activated carbon in cyanide leach solutions

The effect of Ag, Ni and Cu cyanides on gold adsorption on activated coconut carbon in cyanide leach solutions was investigated by synthetic cyanide leach solutions containing gold and other metal cyanides. According to the adsorption tests Ag remarkably reduces the gold adsorption on activated carbon by competing with gold to adsorption sites. When the Ag concentration in solution increases up to 200 ppm the carbon adsorption method for gold recovery becomes inapplicable. Ni has an effect on gold adsorption on activated carbon, however even at as high concentrations of Ni as 250 ppm residual Au in solution is still below 1 ppm. Cu addition up to 300 ppm does not affect the gold loading significantly. According to the adsorption test studies, it is concluded that the metal-cyanides diminish the gold adsorption on activated carbon by adsorbing themselves and competing with gold. When the metals are present in the leach solution all together with gold, they also prevent adsorption of themselves as well as gold. Thus, when Au, Ag, Ni and Cu are present in solution simultaneously, the adsorption of all these metals decreases. The adsorption results were modeled by Fleming k,n adsorption kinetic model.