Mine closure experiences — Bolivia, South America

Bolivia is a well-known mining country, mainly because of its rich tin, silver and gold deposits mined since the Jesuit and Spanish times; 17th to 18th centuries. There are three types of mining sectors: private, state and cooperatives. Within the private sector four closures took place on the highlands: Kori Kollo (Golden Hill) and Kori Chaca (Golden Bridge) projects both located in Oruro, COMCO silver heap leaching Project located in Potosi; and Puquio Norte Gold Project located in the lowlands of Santa Cruz, agitation leaching operation. Within the state sector, there were many mining operations with mine waste and tailings abandoned but not closed. However, in order to mitigate the pollution the Bolivian Government, together with some international donors such as the Danish International Development Agency, have prioritised and encapsulated some tailings deposits in the Potosi Prefecture. The cooperative or artisanal mining sector lacks mine closures. Neither the government nor the communities have forced them to comply with the environmental mining regulations, which have been in force since 1997. Therefore, there are many environmental issues on the sites operated by artisanal miners. This paper reviews the results of the closure efforts of the gold and silver heap leaching operations on the highlands of Oruro and Potosi, where pits, mine waste, evaporation ponds and tailings storage facilities were closed. The paper also addresses another gold agitation leaching operation, in the rainforest which was also closed. In all cases, closure plans and monitoring programmes were executed. Special focus was placed upon the physical and chemical stability of closed facilities so that no further effluents would be released and therefore no major threats would be expected to the environment and nearby communities.