Key Lake mine is a former uranium mine and currently operating uranium mill located in the Athabasca Basin of northern Saskatchewan, Canada, approximately 570 kilometres north of Saskatoon. The site is owned by a joint venture between Cameco Corporation (83.33%) and Orano Canada Inc. (16.67%), with Cameco serving as the operator.
Location and Geography
The Key Lake site lies on the southern rim of the uranium-rich Athabasca Basin, at coordinates 57°12′24″N 105°39′33″W. It is situated within Treaty 10 territory and the traditional territories of the Denesųłiné, Cree, and Métis peoples. The nearest community is the Northern Village of Pinehouse, located 220 kilometres to the south via Saskatchewan Highway 914, which terminates at the mine site.
Geology and Discovery
Uranium exploration in the Key Lake area began in 1969 when uranium anomalies were detected in lake water. In 1971, radioactive pitchblende boulders were found in transported overburden, which were traced back to their source. This led to the discovery of the Gaertner orebody in 1975 and the Deilmann orebody in 1976. The deposits are unconformity-related uranium deposits hosted at the contact between Athabasca Group sandstones and underlying metamorphic basement rocks. The deposits are notable for their high grade, averaging over 2% U₃O₈, and for the close association of uranium with nickel mineralization. Uranium minerals include pitchblende and coffinite, while associated nickel minerals include gersdorffite, millerite, and niccolite.
Mining History
Open-pit mining was conducted at Key Lake from 1983 to 1997. The Gaertner orebody was mined from 1983 to 1987, and the Deilmann orebody was mined from 1989 to 1997. Together, these two deposits produced approximately 209.8 million pounds of U₃O₈ (80.8 million kg U) at an average grade of 2.32%. The Cobble orebody, a zone of uranium-mineralized glacial boulders, was also mined.
Milling Operations
The Key Lake mill began operations in 1983, initially processing ore from the on-site Gaertner and Deilmann deposits. Since 2000, the mill has processed high-grade uranium ore slurry trucked 80 kilometres south from the McArthur River mine, the world's largest high-grade uranium mine. The mill uses a sulphuric acid leach and solvent extraction process to produce uranium oxide (U₃O₈, yellowcake). High-grade McArthur River ore is blended with lower-grade local material before processing. The mill has a licensed annual production capacity of 25 million pounds of U₃O₈ (9.6 million kg U). Ammonium sulfate fertilizer is also produced as a byproduct from recovered reagents.
Tailings Management
Tailings from the milling of Gaertner and Deilmann ores were initially deposited in an Above Ground Tailings Management Facility (AGTMF) from 1983 to 1995. In 1995, the mined-out Deilmann pit was converted into the Deilmann Tailings Management Facility (DTMF), an in-pit tailings facility. Tailings from McArthur River ore are deposited sub-aqueously in the DTMF. The Gaertner pit is used as a tailings management facility for McArthur River tailings and also contains nickel-rich waste rock placed under a water cover.
Production and Operational Status
Between 1983 and 2002, the Key Lake deposits produced 209.8 million pounds of U₃O₈. From 2000 through 2022, the mill processed an additional 126 million kg U (327 million pounds U₃O₈) from McArthur River ore. In November 2017, citing low uranium prices, Cameco announced a temporary suspension of production, and in July 2018 extended this to an indefinite period of care and maintenance. In February 2022, Cameco announced plans to resume production, with first packaged production achieved in November 2022. In 2022, the operation produced 0.44 million kg U (1.1 million pounds U₃O₈).
Environmental Monitoring
The Key Lake operation is subject to comprehensive environmental regulation by the Canadian Nuclear Safety Commission (CNSC) and the Saskatchewan Ministry of Environment. The site operates under an ISO 14001-certified environmental management system. Treated water is discharged to Wolf Lake (from the mill bulk neutralization circuit) and to Horsefly Lake (from the reverse osmosis water treatment plant). Environmental monitoring includes surface water, groundwater, sediment, air quality, soil, lichen, and aquatic biota monitoring. According to the CNSC's 2021 Environmental Protection Review Report, the potential risks from radiological and hazardous releases to the atmospheric, terrestrial, aquatic, and human environments from the Key Lake Operation are low to negligible, and human health outcomes are indistinguishable from those found in similar northern Saskatchewan communities.
Notable Incidents
On 31 December 2004, a lone timber wolf attacked a 55-year-old Cameco employee, Fred Desjarlais, who was jogging back to the mine camp. Desjarlais survived after wrestling the wolf and being rescued by colleagues. Following the attack, an electric fence was built around the site's landfill to prevent further predatory animal incidents.
Decommissioning
Cameco maintains a Preliminary Decommissioning Plan for the Key Lake Operation, with a financial guarantee of $222.5 million (as of 2020). The plan envisions reclaiming all structures and disturbed areas to pre-mining ecological and radiological conditions, with the site intended to be transferred to the Province of Saskatchewan's Institutional Control Program once decommissioning objectives are met.
