The problem

Artisanal, or small scale gold mining (also called ASM) is one of the most significant sources of mercury release into the environment in the developing world, with at least a quarter of the world’s total gold supply coming from such sources. ASM miners combine mercury with gold-carrying silt. The gold and mercury combine to form an amalgam, making recovery of the gold easier. The amalgam is subsequently heated with blow torches or over an open flame so that the mercury burns off, and gold is left at a purity of 70 to 80 percent. The gaseous mercury is subsequently inhaled by the miners, or by their immediate family, including their children. Mercury which is not inhaled during the amalgamation process settles into the surrounding environment, or circulates globally at regional and global scales for future deposition far from the site, where it is absorbed and processed by a variety of living organisms. As a consequence of its misuse, mercury amalgamation results in the discharge of an estimated 1000 tons of mercury per annum which represents about 30% of the world’s anthropogenic mercury releases. It is estimated that between 10 and 15 million artisanal and small scale gold miners worldwide, including 4.5 million women and 600,000 children1. This process transforms elemental mercury into methylmercury. Methylmercury is one of the most toxic organic compounds and a powerful neurotoxin that works its way up the food chain through bioaccumulation. According to UNIDO, as much as 95 percent of all mercury used in ASM mining is released into the environment, constituting a danger on all fronts – economic, environmental and human health. There are a number of cleaner technology alternatives to current methods of mercury amalgamation. The use of retorts during the mercury burn-off stage is a simple and cost-effective way to decrease the occupational exposure to mercury and minimize its release into the environment. Retorts allow for the efficient capture and reuse of mercury. 1 Veiga, M.M., Baker, R. (2004). Protocols for Environmental and Health Assessment of Mercury Released by Artisanal and Small Scale Miners, Report to the Global Mercury Project: Removal of Barriers to Introduction of Cleaner Artisanal Gold Mining and Extraction Technologies, GEF/UNDP/UNIDO, 170p.