Activated carbon is ideally suited to treating low grade ores and tailings by the carbon-in-pulp process and is rapidly replacing the use of zinc for recovering gold from cyanide leach solutions._x000D_
Coarse carbon particles derived from coconut shell adsorb up to 30,000 ppm Au as a gold cyanide complex and can leave barren solutions containing < 0.005 ppm Au. Cold cyanide is stripped from the carbon with difficulty using either hot caustic/cyanide solutions at 90-1200 or aqueous organic cyanide solutions at 25-900 and is subsequently electrowon from the eluant onto steel wool cathodes. A comparison-is made of the Merrill-Crowe zinc process and the activated carbon process with particular regard to possible impurities in the ore and leach solution which may interfere. This is followed by a review of recent research aimed at defining the nature of the active carbon, understanding the kinetics and mechanism of adsorption and developing improved methods of stripping gold from the carbon. It is shown that factors such as temperature, pH, ionic strength and other complex ions affect the kinetics and loading of gold on carbon. The desorption of gold is assisted by the addition of organic solvents, which vary widely in their effect according to the structure and polarity of the solvent.