COMPARATIVE STUDY ON CYANIDE AND ACID LEACHING FOR GOLD, AND SILVER DISSOLUTION FROM DEER TRAIL MINE OXIDE AND TAILINGS ORE

摘要

At the Deer Trail Mine, interest in recovering noble metals from oxide ore and tailings oxide ore with 6.0/1.0 g/t Au and 200/140 g/t Ag respectively has led to metallurgic studies focused on finding an adequate treatment for these materials. Using cyanide leaching, the silver/gold recoveries from oxide ore and oxide tailings were 39 percent /95 percent and 36 percent /96 percent , respectively. Since these recoveries were less than spectacular for silver, it was decided to explore a non-cyanide leaching process that would extract silver and gold better. Based on previous research the possibility of using aqua regia in combination with sulfuric acid was evaluated. On a laboratory scale, variables such as mineralogical composition, concentration of reagents, dissolved oxygen, reaction time, pH and temperature were evaluated. Under optimal conditions it was possible to achieve >65 percent silver recovery and >85 percent gold recovery for both oxide ore and tailings.