Why Use Mercury?
- Bonds with Au forming an amalgam
- Process is quick relative to other recovery methods
- Cost is lower than other recovery methods
- Between 10 to 30% of mercury used in artisanal mining is lost to the environment.
- It is estimated that 196,000 tonnes of Hg was lost in Central and South America from 1570 - 1900 (Nriagu, 1993)
The Effects Include:
Exposure by ingestion, inhalation or contact with skin can lead to:
- damage of the digestive, nervous and immune systems
- kidney and / or lung failure
- complications with fetus development
Artisanal miners are known for exploiting near surface gold deposits. In some cases, to increase the recovery of fine gold these miners will use mercury in their process. Mercury loss is common and can lead to hazardous effects to the local environment.
Mercury in the Environment
- Bacteria can form organic methylmercury
- Both mercury and methylmercury enter the food chain
- methylmercury is able to migrate through cell walls
There are gravity recovery methods that allow for the extraction of fine gold without the use of mercury. However these methods have higher start-up and operation costs versus traditional methods. Government regulation and incentives towards the use of gravity recover methods is required to reduce the unnecessary use of mercury in the future.
Nriagu, J.O., 1993, Legacy of Mercury Pollution: Nature, v. 363, p. 589.