A Mercury-free Gold Extraction Process
Artisanal miners typically use unsophisticated and inefficient methods to concentrate gold. This includes the use of mercury for the final extraction. Mercury is highly toxic and a health hazard to humans and animals, either through direct exposure, or if it enters the food chain. The mercury-free iGoli process has been developed by Mintek to make gold extraction more efficient and environmentally responsible.
iGoli is a simple, safe, and highly effective method of gold extraction that produces an extremely pure product. It consists of leaching the gold concentrate with dilute hydrochloric acid and bleach. After the solids are filtered, the gold is precipitated out with sodium metabisulphate.
The iGoli method has been applied by some South African artisanal miners, and has now been incorporated in a small plant suitable for groups of artisanal miners or very small commercial operators. Plants have been set up in Gauteng and Tanzania.
The technology has been demonstrated to small-scale miners in Mozambique, Peru, and to government officials from Tanzania. The intellectual property is freely passed on because we feel that the removal of mercury from artisanal mining worldwide is important to the health of our earth.
It is recommended that a sample of about 2kg of a concentrate with grade higher than 1000g/t be submitted to Mintek for testing. Based on the results of the tests, Mintek will give the small-scale operator a quote to build a basic plant. Drawings can also be supplied so that the small-scale miner can build his own plant.
- The iGoli Mercury-free gold extraction process;