Gold Extraction

Gold extraction is the set of activities and operations, artisanal or highly technical, aimed at separating gold from its ores or these from the sites that contain them. Various processes, often combined, can be used: grinding, mineral processing, hydrometallurgical and pyrometallurgical processes1.

The extraction of gold from alluvium is carried out by techniques related to the exploitation of the placers, allowing the direct recovery of small gold nuggets and flakes. The techniques for extracting gold from the miners from the middle to the end of the 20th century were generally the work of artisanal miners. Hydraulic mining was widely used during the California gold rush and involved breaking up the alluvium with high pressure water jets. Rock ores have formed the basis of the majority of commercial gold recovery operations since the mid-20th century, where surface and underground mining techniques are used.

Once the ore is mined, it can be treated as whole ore using a heap leach process. This process is typical of low concentration oxide deposits. Normally, the ore is crushed and heaped before leaching. The ores, in high concentrations and the ores resistant to cyanide leaching when the particle size is coarse, require additional treatment in order to recover the gold particles. Processing techniques may include grinding, concentrating, roasting and pressure oxidation prior to cyanidation.