Recent advances in the development of an alternative to the cyanidation process: Thiosulfate leaching and resin in pulp

A process based on thiosulfate leaching followed by resin-in-pulp gold extraction was developed to treat the carbonaceous, preg-robbing ores of Barrick's Goldstrike orebody in the Carlin Trend of Nevada. These ores have proven to be amenable to thiosulfate leaching under mild conditions. Gold leaches rapidly as the gold thiosulfate complex, which, because of its low affinity for graphitic carbon, does not suffer the preg-robbing phenomenon that is a feature of these ores in cyanide leach circuits. The mild leaching conditions are also compatible with a gold-recovery process involving direct recovery from the. leach pulp by adsorption on strong-base anion-exchange resins. Finally, a novel elution/regeneration process was developed to elute the gold off the resin, recover the gold from the eluate and restore the resin for recycling to the adsorption circuit.