Lime-Assisted Cyanide Leaching of Refractory Gold Ores from Ajialongwa Mine

Abstract

Heap leaching is a promising, less expensive, alternative technology for processing low-grade gold ores compared with traditional, energy-intensive processes (e.g., autoclave/tank leaching). The effects of lime on the heap leaching of gold ores from Ajialongwa gold mine in China were investigated. Leach tests included column leach tests, the pilot plant tests, and the commercial plant. The leach experiments were performed using cyanide leaching solutions at pH = 10–11. The results show that the presence of lime greatly increased gold leaching rates. Column leaching experiments show that there was 35.2 % of gold leached without the addition of lime. When 4 % lime was added to gold ores, Au extraction reached 50.56 %. Lime-assisted cyanide of refractory gold was also proved by the pilot plant tests and the commercial plant.