Mercury and Cyanide: The Toxic Divide in Artisanal Gold Mining Practices

A recent social media post from "The Mining Bartender" has highlighted a critical distinction in the chemical processes used in artisanal gold mining, emphasizing the environmental and health hazards associated with both mercury and cyanide. The tweet clarified that mercury is primarily used in placer gold deposits, while cyanide poses issues in other forms of artisanal mining.

"My mistake about placer deposits and cyanide. It’s mercury that is used with placer gold. But there are issues with cyanide and other types of artisanal mining," stated The Mining Bartender on social media.

Mercury amalgamation, a centuries-old technique, is widely employed in artisanal and small-scale gold mining (ASGM) to extract gold from placer deposits. This method involves mixing liquid mercury with gold-bearing sediment to form an amalgam, which is then heated to vaporize the mercury, leaving behind gold. This process is a major global source of mercury pollution, releasing over 1,000 tonnes of mercury annually, accounting for approximately 37% of global emissions.

The environmental and human health impacts of mercury are severe. Inhaled mercury vapor causes neurological damage, kidney damage, and developmental issues, particularly in children and fetuses. Mercury contaminates water and soil, bioaccumulating in the food chain, especially in fish, which is a staple food source in many ASGM regions. The Minamata Convention on Mercury, ratified by over 50 parties, aims to reduce and, where feasible, eliminate mercury use in ASGM.

While mercury is prevalent in placer mining, cyanide is often used in other artisanal mining contexts, particularly for leaching gold from crushed ore or mercury-rich tailings. Cyanide leaching, though more efficient, also presents significant environmental risks. Improper handling or discharge of cyanide solutions can contaminate water sources, posing a threat to aquatic life and human health.

Both mercury and cyanide use in ASGM underscore the complex challenges faced by millions of miners globally. These practices, often conducted in informal sectors with limited oversight, contribute significantly to environmental degradation and public health crises. Efforts are ongoing to promote mercury-free and safer gold extraction methods, such as gravity concentration and borax-facilitated smelting, to mitigate these widespread impacts.