Bolivian state miner Comibol manages the state's interests in mining concessions and metallurgical and industrial plants through joint ventures, lease and/or service agreements with private entities. It is not a mine operator. Comibol currently has 18 projects related to exploration, prospecting and mine development, including the carrying out of lithium exploration work in the Uyuni salt flat. Located in the Bolivian high plains at 3,600m above sea level, the salt flat has a total surface area of around 10,000km2 and contains lithium, boron, magnesium, sodium, calcium and other minerals. In 2015, Comibol secured a US$622mn loan from the Bolivian Central Bank. The funds will go toward building an industrial-scale lithium processing plant at its Uyuni salt flats, as part of the second stage of its national lithium development project. The company also owns the Karachipampa silver-lead smelter, which started production in September, 2014. Comibol took over the plant in 2011 after ending a joint venture with Atlas Precious Metals. The facility has a combined capacity of 51,000t/y silver-lead and in 2015 started to export part of its production. Comibol was formed in 1952 and is based in La Paz, Bolivia.