Artisanal Miners Risk Mercury Poisoning

Artisanal miners in Indonesia panning mercury in open water - photo by Cody Hopkins
Artisanal miners in Indonesia panning mercury in open water – photo by Cody Hopkins

UBC Reports | Vol. 51 | No. 12 | Dec. 1, 2005

Student works for healthier mining technologies

By Brian Lin

When Cody Hopkins witnessed four Indonesian artisanal gold miners narrowly escape a landslide last summer, it hit home what a big difference he could make with a degree in mining engineering.

Hopkins, a fourth-year student in UBC’s Dept. of Mining Engineering, spent three weeks in Indonesia with the Global Mercury Project (GMP), a UN-funded project aimed at providing gold miners in developing countries with healthier, more efficient mining technologies.

“We are currently witnessing the biggest gold rush the world has ever seen,” says UBC Mining Engineering Assoc. Prof. Marcello Veiga, the world’s leading researcher in mercury contamination from artisanal mining, and Chief Technical Advisor of the GMP. “In more than 50 countries, there are 15 million people working as artisanal gold miners, including four million women and two million children.”

As a result of artisanal miners using mercury to extract minute quantities of gold — too little to make economic sense for large-scale mining companies, but enough to put food on the table for poverty-stricken rural communities — more than 1,000 tonnes of mercury are released back into the environment each year.

The powerful poison damages the brain and kidneys when inhaled or ingested through the food chain. It is especially dangerous for developing babies and small children, many of whom work side-by-side with women artisanal miners.

Both stages of the extraction process bring miners into direct contact with mercury. The first involves miners wringing out excess mercury with their bare hands — usually into a pond or river. The small amounts of gold-mercury amalgam produced in the first stage is then burned — in open air or a closed room, often with children present — to vapourize the mercury and further purify the amalgam.

Ironically, most mercury used by artisanal miners is recycled mercury imported from the developed world.

Inspired by Prof. Veiga’s work — Hopkins took a third-year course with Veiga — he applied to join the team last summer to collect data to help build a case for the severity of the situation.

“A big part of my work there was administering a breathing test to miners and measuring mercury contamination in their respiratory system,” says Hopkins. “Depending on the method they use to extract gold from the mercury-gold amalgam, miners could measure anywhere from 5,000 to 20,000 nanograms per cubic metre of air, compared to 20 nanograms, which is normal in urban North America.”

While visiting one of the mines, Hopkins witnessed another practice that poses a more immediate danger.

“In some of the alluvial mining sites, miners would spray water jets at the face of an ore-containing soil slope to loosen the structure. They then pump the slurry, or ore-containing mud through a sluice — long, inclined troughs with a straining mechanism to collect gold particles,” says Hopkins.

“I was talking to some miners and all of a sudden there was this loud thump and I saw the entire top section of the slope tumble to the bottom, almost falling on one of the miners. That was when it really hit me that what we’re doing here could really make a difference.”

Since returning to UBC, Hopkins has been helping design simple retorts, or devices made of common kitchen items and cheap plumbing tools readily accessible to miners that prevent mercury vapour from being released into the air.

Attacking the problem simultaneously from another angle, he’s also working with other engineering students to find ways that help miners increase their yield by investigating the feasibility of a magnetic sluice for areas rich in magnetic minerals, or magnetite.

“Most sluices in the area are lined with carpets or other cheap fibres,” says Hopkins. “As slurry flows through, gold particles, which are heavier, sink and get trapped among the fibres. By attaching magnets underneath the sluice, magnetite that is already present in the slurry would create a temporary, fine-toothed strainer that would catch more gold.”

Hopkins, who has always been interested in the environmental aspect of mining engineering, says his experience with the GMP helped solidify his career aspirations.

“Now I know there are things I can do with what I learned in school that will make a difference in people’s lives.”