Mercury management in small-scale mining

摘要

Recently a combination of economic and social factors mostly in developing countries has resulted in a gold rush by individual small-scale miners, for whom mercury amalgamation is a cheap reliable and portable process. Small-scale gold mining is a source of income for many people in the world, especially in Latin America. However, there is an environmental concern because most of the gold is extracted by mercury amalgamation. leading to the introduction of this metal into the ecosystems. Mercury problems related to small-scale gold mining require the conception, design and implementation of adequate methods for mercury utilisation, monitoring and to mitigation of mercury emissions into the environment. Small-scale gold mining activities have increased in the developing countries of Central and South America, Asia, Africa and Oceania, with many people using mercury to extract gold. Mercury (Hg) is widely used to separate fine gold particles through an amalgamation process from alluvial gold ores. During the amalgamation process a variable amount of metallic mercury is lost to rivers and soils through handling in rough field conditions and to the atmosphere through evaporation. Mercury is easily transformed into stable and highly toxic Me-Hg by numerous microorganisms. This Hg species accumulates strongly in aquatic biota, resulting in contamination of fish and other aquatic species. Some of the miners who burn amalgam show signs of mercurialism while fish-eating people living some distance from mining activities show high Hg concentrations in the blood. There are two mercury problems: the existing problem and future avoidance of the problem ~1.