Optimization of the Process of Gold Leaching from Arsenic-Bearing Gold Ore Using an Oxidizing Agent in Heap Leaching

The results of laboratory studies for gold recovery from sulfide and oxidized ores under percolation (heap) leaching are presented in this article. The results of chemical elemental analysis, X-ray phase, and mineralogical analyses for the forms of gold deportment in ore are also presented herein. The percolation heap leaching process of low-grade ore in percolation columns was simulated. The efficiency of cyanide leaching and leaching with the use of an oxidizing agent in percolation columns was compared. The initial sulfide ore is refractory for processing by the agitation leaching method. Gold recovery under standard cyanidation of 0.1–0.3% sulfide ore with 90% particle size of -0.071 mm averages 32.0/47.0% (the gold content in the leaching residue is 1.36–1.05 g/t, respectively), while it is 60.0% in agitation mode with the use of the oxidizing agent (TCCA). The results showed that direct cyanidation at various concentrations recovers 45.0–75.0% from oxidized ore, with the presence of the oxidizing agent trichloroisocyanuric acid (TCCA) at the rate of 76.67%. Percolation leaching of oxidized ore conducted under optimal conditions at a concentration of 0.3% CN– with the use of TCCA, with an irrigation pause of two days, at an irrigation rate of 20–30 dm³/t, allowed to recover 53–62% of gold into solution within 30 days, respectively.