EFFECT OF DEAERATION ON GOLD RECOVERY FROM GOLD THIOUREA COMPLEX SOLUTION USING CARBON ADSORPTION AND LEAD CEMENTATION

The recoveries of gold from thiourea leach solutions of Cimanggu-type ore using lead cementation and carbon adsorption were found to be around 50%. A series of lead cementation and carbon adsorption experiments of laboratory scale was set up to improve the gold recovery. The effect of deaeration on gold recoveries in thiourea system was investigated. The study revealed that the reversed effect of dissolved oxygen on gold recovery in thiourea system is observed, as compared with the cyanide system. While recovery of gold from aurocyanide complex solution by cementation is improved under deaerated condition, gold recovery is decreased when deaeration is applied to the thiourea system. Meanwhile, recovery of gold from thiourea complex solution is increased as deaeration is performed during carbon adsorption, which is practised under atmospheric pressure in cyanide system. Under deaerated condition, gold recoveries of 73% and 29% are achieved using carbon adsorption and lead cementation, respectively. A gold recovery of 81% is obtained when a longer retention time (= 4 hours) is applied to the carbon adsorption process. The proposed mechanisms for both processes are described.