Introduction of Mercury-free Gold Extraction Methods to Medium-Scale Miners and Education of Health Care Providers to Reduce the use of Mercury in Sorata, Bolivia

Abstract

Background. Artisanal and small-scale miners in Bolivia release on the order of 120 tons of mercury annually. The mercury finds its way to the Amazon with catastrophic consequences for the biosphere. A project aimed at reducing the release of mercury was carried out in 2013 and 2014. Objectives. The project had two objectives: to test whether the mercury-free gold extraction method could be an alternative to whole ore amalgamation in medium-scale mining in Bolivia and to teach mercury toxicology to health care providers in the gold mining area. The mercury-free gold extraction method has been successfully introduced in other countries, but mainly in very small-scale mining communities. Materials and Methods. The targets in Bolivia were medium-scale miners processing over a hundred tons of ore per day. The chosen gold ores proved amenable to gold extraction using mercury-free extraction. Demonstrations of the mercury-free methods were carried out by processing similar quantities of gold ores using the amalgamation and the mercury-free method. Miners, mining communities and local health providers were informed on the toxicity of mercury. Health providers were shown how to conduct epidemiological surveillance. Posters explaining the path of mercury from the processing stations to local households were prepared. Conclusions. The gold ores tested during the project proved amenable to mercury-free gold extraction using borax smelting. The miners also realized that gold recovery increased when performing mercury-free gold extraction. The miners decided to stop using mercury and a follow-up project cleaned their mining equipment for mercury and modified the processing lines. The health care providers were also successfully trained.

Keywords

• Mercury-free medium-scale gold mining
• Bolivia
• Borax smelting
• Mercury toxicity