In-Situ Leach Mining of Uranium in the Permafrost Zone, Khiagda Mine, Russian Federation

The 'Khiagda' mine in the Republic of Buryatia is the only ISL mine in the world where ore mining is performed in a permafrost region. The uranium resources of the Khiagdinsky ore field deposits amount to 48 000 t. The ore field is a part of the Vitimsky Uranium ore district with 100 000 t resources. This is the most promising region in Russia where the deposits may be extracted by the ISL technique. Throughout a year, the air temperature varies from +35 to –45°C. Permafrost zone is developed to a 90-m depth. The Khiagdinsky ore field includes 8 deposits. Mineralization hosting sediments occur below the basalt sheet cover at a depth of 90 to 280 m. The rigorous climatic conditions, high degree of reduced uranium, complicated hydrogeological conditions and high viscosity of a very cold groundwater caused low uranium recovery at the initial stage of development. The carried out extensive scientific and research works and in particular, the use of an oxidant, made it possible, to increase significantly the uranium concentration in the productive solutions, which is currently comparable to world best examples. (author)