Gold is a beautiful commodity which sadly does not come mined from the ground without its consequences. Artisanal and small-scale gold mining and refining is responsible for the largest releases of mercury into the environment and atmosphere than any other global sectors. Approximately 400 metric tonnes of airborne elemental mercury is released each year by these sources, which can be incredibly detrimental to our health and our surroundings.
(Liquid mercury, image courtesy of Global Environmental Facility)
Situated in over 55 countries worldwide, small scale gold buying and refining facilities (also known as ‘gold shops’) are an important part of the gold production process and are the major source of this air pollution. If inhaled or ingested, mercury poisoning can induce harmful health effects such as loss of vision, lack of coordination, change in nerve responses and muscle weakening. In serious cases, mercury poisoning can also damage your brain, heart, lungs, kidneys, and immune system.
To try and tackle these harmful metallic pollutants escaping into our atmosphere, the Environmental Protection Agency and Argonne National Laboratory have teamed up to create a low cost, easily constructable technology called the Gold Shop Mercury Capture System (or MCS). This system is constructed from a 55-gallon steel drum where mercury is cooled, condensed, and collected as liquid for safe management and storage. This technology is not only simple to construct, but also incredibly low cost and easy to transport.
(EPA Mercury Capture System, image courtesy of SlideShare)
The MCS was trialled in Peru and Brazil within Amazonian gold producing regions. Since the testing within 2008, Peru has developed a strategy to implement this new innovative technology amongst nationwide gold mines. Performance tests indicated that the MCS technology reduced airborne mercury emissions within gold shops by 80 percent, which is a significant reduction in those regions which do not have access to any form of effective mercury control technology. If used continuously and efficiently, the instillation of these mercury capturing systems can prevent the release of more than 200 metric tons of mercury into the atmosphere annually.
(An ASGM gold shop processing cycle, image courtesy of UNEP)
Data collected during site visits to various gold refining locations showed that in shops with the installed MCS technology, mercury vapor concentrations were close to the American Conference of Governmental Industrial Hygienists threshold limit value (ACGIH TLV) for occupational exposure (25 ug/m3). Gold shops that did not have the MCS technology installed had mean ambient mercury vapor concentrations that were 5-20 times higher than those shops which had the MCS installed. This is a brilliant and promising result within the gold mining industry; this precious commodity can continue to be mined and produced whilst simultaneously cutting down its significant mercury emissions and detrimental repercussions.