Experimental Study on the Gold Extracted from Carbonaceous Gold Ore Leached in Heaps by Preoxidized

The preoxidized roast process and direct leaching in heaps of the roasted ore from a low-sulfur carbonaceous silicified gold mine in Dandong, Liaoning Province were studied experimentally, of which the roasted /oxidized conditions of gold ore and main influencing factors on leaching rate of gold were investigated under different temperatures, atmospheres and times, such as the weight% of NaCN, spraying intensity, grain size of roasted ore and spraying time. As a result, the oxidizing rate and ashing rate of the sulphides and carbonaceous material can be up to 98% and 97%, respectively, if roasting the ore for 1 h (for dearsenification) at 450 ℃ and ventilated with a bit of air to provide 5%～10% of oxygen content in air and, further, roasting it for 2 h at 650 ℃and ventilated with full air. The leaching rate of gold is 84.8% if the weight% of NaCN is 0.10%～0.15%, spraying intensity 150 L/(m~2·h), grain size of roasted ore 0～3 mm and spraying time 8～10 days. The basic technological process of direct leaching in heaps of roasted ore is recommended with the intention of laying a foundation for industrial applications.