Gold Recovery in Heap Leaching of Old Mine Tailings Using Chloride Solution

Abstract

The closure of hydrometallurgical plants due to mineral reserve depletion prompts exploration into alternative solutions, such as processing gold tailing ores. Despite challenges posed by minerals like hydronium jarosite and sulfides, which hinder gold dissolution in conventional cyanide leaching, preliminary investigations of utilizing chloride oxidation on an old mine tailing dump showed some promising results. This study aims to assess the efficacy of this technique on refractory gold tailings, employing acid leaching with sodium hypochlorite, sodium chloride, and hydrochloric acid. Various factors affecting gold extraction from heap leaching, such as agglomeration blending ratios, pellet size, leaching pH, bed height, and spraying rate, were evaluated. Results indicate a > 40% increase in gold extraction with chloride-based heap leaching. This innovative approach offers a promising alternative for liberating gold from sulfide ores within tailings, potentially mitigating the challenges associated with conventional methods and revitalizing hydrometallurgical operations.