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Small-scale mining in Tanzania

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Small-scale miners crushing gold ore.
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In 1999 GEUS carried out a project entitled: An integrated approach to mineral exploration and environmental assessment in southern and eastern Africa - a pilot study in Tanzania. The study was supported by the Danish Council for Development Research (RUF project number 90953).

A small part of the project comprised investigation on working conditions and uses of extraction techniques by small-scale miners in the Lake Tanganyika area. It was found that the main extraction technique was mercury and that none of the small-scale miners had any knowledge of ways to recycle the mercury.

The pilot project comprised compilation and integrated evaluation of existing geoscience and environmental data from Western Tanzania, as well as field work carried out jointly by geologists from Denmark and Tanzania. The pilot project was for one year and terminated 15 March 2000.

The field work comprised detailed studies and sampling of the numerous small gold deposits in West Tanzania near Lake Tanganyika, with the aim of determining how the deposits were formed and thereby providing tools for discovering new gold deposits in the area. The gold deposits are presently all mined by thousands of small-scale miners. All mining, crushing and grinding are done by hand and the ground ore is treated with metallic mercury, whereby the very fine-grained gold amalgamates with the mercury. The mercury is subsequently burned off over small fires.

Large quantities of mercury are released into the environment during the amalgamation. Some of this mercury is inhaled by amalgamists and nearby villagers. The remaining mercury enters the drainage system where it is incorporated in the food chain. The pilot project comprised investigations as to how much mercury and other metals were dispersed into the drainage system by sampling stream sediments. Furthermore samples of fish, porridge and human hair were collected. The analyses showed that several of the miners had very high contents of mercury in their hair. The mercury used in amalgamation poses serious health problems to the population of West Tanzania and one of the aims of the pilot project was to reveal means to reduce the release of mercury into the environment.

The project was carried out in collaboration with the National Environmental Research Institute, Denmark, the Department of Geology, University of Dar es Salaam and the Geological Survey of Tanzania with GEUS as project manager. The project was financed by the Danish Council of Development Research (RUF).

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Hent (download) rapport, december 2004:
An integrated approach to mineral exploration and environmental assessment in southern and eastern Africa - a pilot study in Tanzania
RUF_project_90953.pdf (pdf-file ~1,3 mb)
Report on the project supported by the Danish Council for Development Research(RUF project number 90953)

Læs også fakta ark: Sustainable development of small-scale mining
og kig på: Global Mercury Forum


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Retort made of a few inexpensive pieces of plumbing .
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Young boy burning off mercury during extraction of gold.

Golden Livelihoods? Investigating upgrading Potentials within Artisanal and Small-Scale Gold Mining in Tanzania

In 2005 a two and a half year joint project was funded between GEUS and Institute of Geography at the University of Copenhagen. The project will focus on small-scale gold mining in Tanzania. Main part of the project will be carried out by a Ph. D. student Jesper Bosse Joensson ( jbj@geogr.ku.dk)

GEUS part of the project is to conduct a teaching and training programme for small-scale miners in improved extraction techniques such as mercury recycling devises (retorts). GEUS part of the project will take place in October 2006 and will be followed up later in the autumn of 2007.


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