Cigar Lake Uranium Mine, Saskatchewan, Canada
Cigar Lake is the world's largest undeveloped uranium deposit. The mine is located in Saskatchewan, Canada. It is owned by Cameco Corporation, Areva, Idemitsu and TEPCO, and is operated by Cameco Corporation. Cigar Lake mine was expected to commence operations from 2007, but heavy water inflow in October 2006 delayed the start of operations. Uranium production is expected to commence in 2013.
Geology and mineralisation at the Canadian mine
Cigar Lake deposit is located in the Athabasca basin and forms part of Manitou Falls Formation. The deposit is approximately 1,950m long and 500m deep below the surface. It is a flat lying deposit with sandstone lying upon the basement rock.
Cigar Lake deposit comprises of three types of mineralisation, which include high grade mineralisation or unconformity mineralisation, perched mineralisation and basement rock mineralisation.
High grade mineralisation refers to the high-grade uranium contained zones in the deposit. Huge portions of quartz, clay and metallic minerals are also deposited in this region.
High grade mineralisation was considered the viable zone of production in Cigar Lake, based on the mining method and ground conditions. Perched and basement rock mineralisations form very small part of the total mineralised rock in terms of volume.
Reserves and exploration at Cigar Lake
Cigar Lake mine is estimated to have 537,100t of uranium reserves, including proven reserves of 233,000t and probable reserves of more than 300,000t of uranium.
Cigar Lake's uranium deposits were discovered in 1981. The delineation activity was done from 1982 to 1986 and holes were drilled until 2002 for geotechnical studies. A total of 406 surface holes were drilled to delineate the deposit.
Diamond core drilling was also done at the mine from 1981. It was conducted in underground locations to determine the rock mass characteristics. A total of 222 holes were drilled from 1981 to 2011.
Mining methods used at the uranium mine
Cigar Lake will be mined using underground methods. The basement rock layer of Cigar Lake comprises of two levels, 480m and 500m. Mining will be conducted in the 480m level area, which is 25m below the ore zone. Underground processing and infrastructure facilities are located in this level.
The 500m level provides main ventilation exhaust drift for the mine and is accessed via a ramp from the 480m level.
Jet bore system (JBS) will be used in the mine. The system involves usage of high pressure water to cut cavities from the ore. It is a non-entry approach, where personnel will not get in direct contact with the orebody as all the mining will be down in the basement rock below the orebody. The mine will be equipped with four JBS mining units.
The process involving JBS includes mixing of the ore with water to form slurry, which will be pumped through pipes to the Run-of-Mine (ROM) ore receiving facility.
The ore slurry will be transferred to the surface through a slurry pump. The slurry will be stored and then transferred to McClean Lake JEB mill for processing.
Processing uranium ore at Cigar Lake
The uranium ore will be processed partly at Cigar Lake and partly at McClean Lake JEB mill, which is located 70km north of Cigar Lake. Ore size reduction will be done at the underground region of Cigar Lake, while leaching, purification and final yellowcake production will be done at McClean Lake JEB mill.
The ore slurry stored at Cigar Lake will be transported to McClean Lake JEB mill through containers. The slurry will be leached and treated in the McClean Lake mill tailings neutralisation area and ore tailings will be generated. The tailings will be thickened with vacuum and precipitated to form yellowcake.
Production and contractors involved
The mine is anticipated to produce 18 million pounds of U3O8 annually during its expected lifespan of 15 years. The daily production is estimated to be 140t.
Tron Power will provide construction services for the Cigar Lake mine. The services will include underground electrical construction and maintenance, jet boring pilot project piping and water treatment plant foundation. The contract for the planning, procurement, construction, fabrication and field construction of Cigar Lake mine was awarded to Canonbie.
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