Cyanide Leaching of Copper Gold Silver Ores
Copper leaching is currently carried out in sulphuric acid media, where the process is highly known and where metallurgical and economic performances are mostly reliable. However, acid leaching is...
Leaching, often gold, is the process of extracting a soluble constituent from a solid by means of a solvent. In extractive metallurgy, of gold, it is the process of dissolving a certain mineral from an ore or a concentrate, or dissolving certain constituents from materials such as a calcines, mattes, scrap alloys, anodic slimes, etc., to achieve either one or two purposes ...
In the case of gold recovery, heap leaching generally requires 60 to 90 days to leach the ore, compared to the 24 hours required by a conventional agitated leach process. Gold recovery is also usually only 70% compared with 90% recovery in an agitated leach plant.
Leaching Once Vat is loaded with ore, is flooded with a leaching solution of a desired cyanide concentration and pH between 10 to 11 at ambient operating conditions through the filter section of the floor or added to the top of the ore charge.
Thiosulfate leaching offers a number of benefits related to gold recovery yields and environmental concerns: Thiosulfate leaching of gold ores has great potential to reduce the impact on the environment. Unlike cyanide, which is highly toxic, the chemicals used in the thiosulfate leaching process are benign.
Both oxide and sulfide ores can be leached, though the leach cycles are much different and sulfide leaching requires a bacterial, or bio leach, component. In 2011 leaching, both heap leaching and in situ leaching, produced 3.4 million metric tons of copper, 22 percent of world production.
The mined oxide gold ore is often crushed and then stacked over a leach pad which is lined with an impenetrable polyethylen e or polypropylene material. Some mines use run of mine ore with no crushing at all. This is cheaper, but often leads to the compaction problems discussed above.