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Mercury Is a Fascinating Metal, But Its Use in Gold Extraction Can Bring Serious Risks. Discover How This Process Works and Its Consequences.
Mercury plays a fundamental role in gold mining throughout the centuries. Its unique ability to form amalgams with gold has made it an indispensable tool for artisanal miners artisanal.
However, despite its effectiveness, the use of mercury brings severe environmental and health consequences. This article examines the history of the use of mercury in mining, its impacts, and emerging technological alternatives to mitigate its adverse effects.
Chemical Characteristics and History of Mercury Use
Mercury is a liquid metal at room temperature, an uncommon characteristic among the elements in the periodic table. With a density of 13.6 g/cm³, it has a high surface tension and a silvery color. Its name derives from the Latin ‘argentum vivum’, or “living silver”, due to its shiny appearance and fluidity.
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Historical records indicate that mercury was known in Ancient Egypt around 1500 B.C., being used in medicine and alchemical processes.
However, its role in mining was documented around 750 B.C., when ancient civilizations began using it to extract gold and silver from ores.
The Amalgamation Process and Gold Extraction
The amalgamation method is based on the high chemical affinity of mercury for gold. When liquid mercury is mixed with sediments containing gold, a compound known as gold amalgam is formed. This process facilitates the separation of gold from other minerals present in the rock.
After the formation of the amalgam, the material is subjected to compression in a porous fabric, such as buckskin, to remove the excess mercury.
Next, the mixture is heated to temperatures above 356.7 °C, promoting the vaporization of mercury and leaving behind pure gold.
The vaporized mercury can be collected and reused, but in artisanal mining, it is often released directly into the environment.
Environmental Consequences and Public Health
The volatilization of mercury during the burning of amalgam represents one of the greatest environmental challenges associated with mining.
Inhaling elemental mercury vapor can cause chronic poisoning, affecting the central nervous system and causing symptoms such as tremors, memory loss, and cognitive difficulties.
Moreover, mercury released into nature can undergo methylation by bacteria present in soil and water, forming methylmercury, a highly toxic compound that bioaccumulates in aquatic organisms.
This poses a threat to communities that depend on fishing as a food source, as the consumption of contaminated fish can lead to mercury poisoning.
The Persistence of Artisanal and Small-Scale Mining (ASM)
Despite the known risks, artisanal mining still relies on mercury due to its low cost and ease of use.
It is estimated that between 10 and 19 million people are involved in artisanal mining in over 70 countries, mainly in developing regions.
This sector is responsible for approximately 37% of global gold production, releasing about 1,000 tons of mercury into the environment annually.
The lack of regulation and the precarious working conditions contribute to the continuation of this method, especially in economically vulnerable communities.
Mercury contamination affects not only the miners but the entire ecological and social chain around extraction areas.
Technological Alternatives and Sustainable Methods In light of the need to reduce dependence on mercury, researchers and institutions have developed alternative methods for gold extraction. Techniques such as flotation, gravitational concentration, and the use of controlled cyanidation are being promoted as safer and more efficient alternatives.
The use of gravity centrifuges has shown promise, as it allows for the separation of gold without the need for mercury.
Additionally, training programs and capacity-building in sustainable mining practices have been implemented to raise awareness among communities about the risks of mercury and encourage them to adopt safer methods.
Global Initiatives
Various international efforts have been made to reduce the impact of mercury contamination. The Minamata Convention, adopted by the UN in 2013 and ratified by several countries, establishes guidelines for the gradual elimination of mercury use in industrial activities and artisanal mining.
Moreover, the implementation of portable sensors to detect the presence of mercury in mining areas can assist in mitigating risks.
Governments and NGOs have worked together to provide financial incentives for the adoption of clean technologies and to regulate the use of mercury on a small scale.
Future Perspectives The transition to more sustainable mining methods relies on a multidisciplinary approach, involving effective public policies, technological development, and social awareness.
With investments in innovation and a coordinated global effort, artisanal mining can be transformed into a safer activity for workers and the environment.
The use of mercury in gold mining, while historically significant, poses a substantial risk to the environment and public health.
Mercury contamination remains a global concern, requiring ongoing efforts to mitigate its effects and replace its use with more sustainable methods.
Commitment to technological alternatives and effective regulations is essential to ensure that gold mining occurs in a responsible and environmentally conscious manner.
With information from iflscience
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