Unlocking gold recovery: Optimizing leaching process from tailing sluice boxes with HCl pretreatment and cyanide concentration variations

Tailing sluice box still contains 4.96 gpt of gold. Samples were taken for XRD and SEM-EDX testing. The XRD test results show that quartz is the dominant mineral, followed by clay and feldspar. Quartz mineral content is 46.87%, clay mineral content is 17.76% and feldspar mineral content is 27.80%. The clay mineral content which tends to be high affects the leaching process which makes the reaction take longer. The results of the diagnostic leach test using HCl solution and cyanide solution resulted in 39% Au gain. The results of the HCl pretreatment on the tailings grain size -150, -200, and -270 mesh got Au gain percentage of 23.6%, 29.6%, 44%. Tailings leaching with variations in cyanide concentrations of 500 ppm, 750 ppm and 1000 ppm resulted in gold recovery of 0.8%, 5.8%, and 7.8%. The highest gold gain was at - 270mesh size and 1000ppm cyanide concentration with 72 hours leaching time.