Imouraren Uranium Mine, Niger
Imouraren mine is the largest uranium deposit in Africa and world's second-largest uranium deposit. The mine is located in Imouraren, Niger. It is located 80km south of Arlit mine and is estimated to contain 179,000 tonnes of uranium deposits.
French nuclear energy company Areva is the developer of the mine. The mine is co-owned by AREVA, Sopamin and by KEPCO (South Korea).
The development of the mine is expected to create 1,800 direct jobs and 3,500 indirect jobs during its estimated production period of 35 years. The mine is expected to start production in 2015.
Imouraren uranium mine geology and development
Imouraren mine is located in the Tchirezrine sandstone which is of the Jurassic-Cretaceous period. The deposit forms part of the Guezouman conglomeratic formation. Palaeozoic volcanic rocks are widely found in this region.
The region contains Sandstone-type uranium deposits. The deposit is extended over eight kilometres long and 2.5km wide, and is located at an average depth of 130m.
Uranium deposits in the Imouraren region were discovered in 1966 but the mine was not developed due to the unfavourable uranium market. Areva obtained an exploration permit for the mine in 2006 and conducted prefeasibility and environmental impact studies in 2007.
Mining permission was obtained in 2009 and the operational launch was carried out in 2010. The mining installations are expected to be completed by 2013.
Uranium reserves and production
Imouraren mine is estimated to contain reserves of 179,000t of uranium. The mine is expected to start production in 2015. It is estimated to produce 5,000t of uranium yellowcake (U2O4) per year for a period of 35 years.
Edf Group will purchase 20,000t of uranium from the mine, as part of an agreement signed with Areva. The mine is expected to witness the extraction of four billion tonnes of waste rocks and ore during its life span.
Uranium mining and processing at Imouraren
The Imouraren uranium mine development project was launched in 2010. Rock layers above the uranium deposits have been removed. Dewatering pumping systems have been installed in order to reduce the chances of water flowing into the mine during the mining process.
Dynamic leaching and heap leaching methods will be used for ore extraction at the Imouraren mine. The acid heap leaching method will be followed for low-grade mineralised ore body.
Under the heap leaching method, the ore from the mine will be crushed and transferred to leach pad using mobile conveyors and radial stackers.
Sulphuric acid is added to the ore and a substance containing uranium will be separated from the ore. Yellow cake of uranium is then produced by processing the substance.
Construction at Niger's Imouraren mine
The leach pad used in acid heap leaching has been constructed in an area of more than 42 acres. The on-off heap leach pad includes radial stacker, mobile conveyors and overland conveyor. The tailings facility uses 35t capacity trucks.
A drainage layer has been formed through the ore heap in order to provide for the acid circulation of solution. This helps in the recovery of uranium bearing solution.
Construction works also included the installation of equipment for chemical processing which are used for ore treatment. The chemical processing involves a number of steps including extraction, decantation, washing, drying and packaging.
Environmental measures adopted for mining the deposit
Eco-design approach is followed to find ways to conserve water and reduce much water consumption. The length of the ore conveyor length has been optimised so as to reduce the energy consumption.
A cogeneration system has been installed at the sulphuric acid plant in the Imouraren mine. The steam generated will be used partly in the chemical plants and partly to produce electricity.
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