1. Cigar Lake

2021 production: 4,693 MT

In Canada, Northern Saskatchewan-based Cigar Lake is number one on this list of the world's top uranium mines. It is known for being the highest-grade uranium mine, with an average grade of 14.69 percent U3O8. Canada is the third-largest uranium producing country.

Uranium miner Cameco (TSX:CCO,NYSE:CCJ) owns 54.547 percent of Cigar Lake and is the mine's operator. Ore from the underground mining property is processed at Orano's McClean Lake mill, located 70 kilometers from the mine.

Throughout 2020, operations were halted and started only to be halted again by a series of COVID-19 outbreaks. Cameco restarted uranium production in April 2021 only to have to again close up shop temporarily in July 2021 as fires in the region led to evacuations. The company expects to produce 18 million pounds (8,164 MT) in 2022.

Cigar Lake was commissioned in 2014 and began commercial uranium production in May 2015. It accounted for 10 percent of global uranium output in 2021. Orano (40.45 percent), and TEPCO Resources (5 percent) also hold stakes in the mine.

2. Inkai, sites 1 to 3

2021 production: 3,449 MT

The in situ recovery Inkai uranium mine in Kazakhstan is a joint venture between Cameco (40 percent) and state-owned uranium miner Kazatomprom (60 percent). Inkai accounted for 7 percent of the world's uranium output in 2021.

Kazatomprom's operations have also been impacted by COVID-19, with the company announcing in early April 2020 that it was reducing operational activities at all of its mines in Kazakhstan for several months. The company resumed operations in August of that year. 2021 saw further disruptions to uranium mining operations in the country brought on by political unrest.

3. Husab

2021 production: 3,309 MT

Next up on this list of top uranium mines is the Husab open-pit uranium mine in Namibia, which is owned by Swakop Uranium, a partnership between China and Namibia. Epangelo Mining Company, a Namibian state-owned entity, owns 10 percent of Swakop, while Taurus Minerals holds the other 90 percent; Taurus itself is owned by China General Nuclear Power Group and the China Africa Development Fund.

According to the Namibia Uranium Association, Husab represents China's single largest investment in Africa. Husab was discovered in 2008, and produced its first drum of uranium oxide for export in December 2016. As of 2021, the operation accounted for 7 percent of global uranium production. Namibia was the world's second largest uranium producing country behind Kazakhstan in 2021.

4. Karatua (Budenovskoye 2)

2021:production: 2,561 MT

The in situ recovery Budenovskoye 2 operation, located in Kazakhstan at the Karatau mine, produced 5 percent of the world's uranium in 2021. The Karatau mine is owned by the Karatau joint venture, a Kazakh-registered limited liability partnership that is held by uranium producer Kazatomprom and Uranium One.

Uranium One is a subsidiary of ROSATOM, Russia's state-owned nuclear energy company. Uranium One takes care of ROSATOM's uranium output outside Russia.

Karatau started producing in 2009, and the joint venture has the right to carry on exploration, mining and sales operations at Budenovskoye 2 under a long-term subsoil use contract with Kazakhstan.

5. Rössing

2021 production: 2,444 MT

The Namibia-based Rössing uranium mine was responsible for 5 percent of the world's production in 2021. The open pit has operated since 1976 and was the country's first commercial uranium mine.

Rio Tinto (ASX:RIO,LSE:RIO,NYSE:RIO) was the company that brought Rössing into production, but it is no longer involved in the mine. In November 2018, Rio Tinto announced that it would be selling its majority stake of 68.62 percent, and it completed the sale in July 2019. Rio Tinto sold its share of Rössing to China National Uranium.

Aside from China National Uranium, a number of companies have interests in Rössing. The Namibian government has 3 percent, the Iranian Foreign Investment Company has 15 percent, the Industrial Development Corporation of South Africa owns 10 percent and individual shareholders own the rest.

6. Four Mile

2021 production: 2,241 MT

Quasar Resources' Four Mile in situ leach operation is the top uranium producing mine in Australia. The high-grade, roll-front deposit was discovered in 2005 about 8 kilometers from the formerly producing Beverly uranium mine. Construction of the mine began in December 2013, followed by commercial production in June 2014.

Four Mile produced 5 percent of the world's production for uranium in 2021. The deposit is also prospective for iron-oxide and copper-gold mineralization.

7. SOMAIR

2021 production: 1,996 MT

SOMAIR is a subsidiary of uranium producer Orano that operates in Niger; it is 63.4 percent owned by Orano and 36.66 percent owned by Sopamin, the state agency that manages mining in Niger. SOMAIR is responsible for a large uranium mine, as is Cominak, another nearby Orano subsidiary in Niger. SOMAIR began production in 1971.

Uranium mining will begin at a third site near SOMAIR and Cominak when market conditions are more favorable. SOMAIR produced 4 percent of the world's total uranium production in 2021.

8. Olympic Dam

2021 production: 1,922 MT

The Olympic Dam mine, owned by BHP (ASX:BHP,NYSE:BHP,LSE:BHP), produces copper, along with uranium, gold and silver. Olympic Dam, which has underground and surface operations plus a fully integrated processing facility, has been in action since 1988, and in 2021 its output accounted for 4 percent of the world's uranium production.

Australia has the largest uranium reserves in the world, and holds about 30 percent of potential global supply. In 2021, the country was the world's fourth largest producer.

9. Central Mynkuduk

2021 production: 1,579 MT

The Central Mynkuduk mine is an in-situ leach uranium mining operation in Kazakhstan held by Ortalyk, a joint venture between Kazatomprom (51 percent) and China General Nuclear (49 percent).

Production began at Central Mynkuduk in 2007 and it accounted for 3 percent of the world's uranium production in 2021.

10. Kharasan 1

2021production: 1,579 MT

Kharasan is an in situ leach operation in the Syr Darya basin of the Kyzylorda region in Kazakhstan. The uranium mine is owned by Kazatomprom (33.98 percent) and Uranium One (30 percent). A consortium of Japanese utilities and a trading company hold the remainder.

Commercial production at Kharasan began in 2013, and in 2021 the operation accounted for 3 percent of the world's uranium production.