Direct extraction of Ag⁺ and Hg²⁺ from cyanide complexes and mode of binding by the layered K₂MgSn₂S₆ (KMS-2)

One of the long-term issues associated with this method is the efficient extraction of the metals from the formed cyanide complexes. Different methods such as zinc-dust cementation, carbon adsorption, solvent extraction, and ion exchange have been used for metal recovery from alkaline cyanide solutions. Some difficulties associated with these methods are high zinc consumption and reaction sensitivity to impurities of the leach liquor in the zinc-dust cementation process. Also a problem is the slow reaction kinetics and carbon fouling due to salt precipitation in the carbon adsorption technique, lack of a selective extractant, and large amount of solvent consumption in the solvent extraction method. Among these methods, ion-exchange technologies have been receiving much attention because they promise to eliminate some of the disadvantages of the other methods. Ore leaching processes using cyanidation technology have been extensively used in industry for over a century.