Construction begins on Canada’s first ISR uranium mine
Published by Markku Björkman - 30 Jul, 2026
Canada has started building a uranium mine that will require neither a large open pit nor conventional underground tunnels. At the Phoenix project in northern Saskatchewan, uranium will be dissolved in the rock and pumped to a processing plant at the surface. A frozen underground barrier will prevent the mining solution from escaping the production area.
Denison Mines has announced that site preparation at the Phoenix uranium mine has been completed and that the project has entered full-scale construction.
The work includes construction of the processing plant, power infrastructure and production wells, as well as installation of an underground freeze wall around the mine’s initial production zone.
Since early works began in March, the site has been cleared, roads and foundations have been prepared, and temporary construction facilities have been established. A new accommodation camp has increased capacity at the Wheeler River property to nearly 400 people.
According to Denison, more than 20 per cent of the overall civil works have already been completed. Concrete pours for the foundations of the main processing plant and electrical substation are expected to begin in August.
A second shift will also be introduced, allowing seasonally sensitive civil and construction work to continue almost around the clock for the remainder of the summer.
– Completing the site-preparation activities needed to increase our on-site workforce and reach a full-scale rate of construction is an important initial milestone for the Phoenix project, says Denison President and CEO David Cates.
Uranium pumped out instead of mined
Phoenix will become the first Canadian uranium mine to use in-situ recovery, known as ISR. The method involves injecting an acidic mining solution through drilled wells and circulating it through uranium-bearing rock.
The solution dissolves the uranium without requiring the entire orebody to be excavated or blasted. The uranium-bearing liquid is then pumped back to the surface, where the uranium is separated and processed into uranium concentrate, commonly known as yellowcake.
ISR already accounts for more than half of global uranium production and is used on a large scale, particularly in Kazakhstan. However, the technique has never previously been used commercially at a Canadian uranium mine.
The method does not generate conventional waste-rock piles or tailings facilities of the type associated with traditional uranium mining. It does, however, require careful control of groundwater and of the mining solution circulating through the deposit.
Phoenix also differs from many other ISR projects because its uranium ore is located in a water-bearing sandstone environment.
Denison therefore plans to drill a ring of freeze holes around the production area. Refrigerated fluid circulated through the holes will freeze the surrounding ground, creating a barrier up to 10 metres thick.
The frozen wall is intended to reduce groundwater movement and keep the mining solution inside the designated production zone.
It will be constructed in stages. Only the barrier surrounding the first production area must be completed before operations begin. Additional sections can then be frozen as extraction progresses through the deposit, reducing the project’s initial capital requirements.
Construction licence does not yet permit production
The Canadian Nuclear Safety Commission, CNSC, approved the project’s environmental assessment and issued a construction licence in February 2026.
The licence allows Denison to prepare the site and build the mine and processing facilities. It does not yet permit the company to begin commercial uranium production.
A separate operating licence must be applied for and considered through a future public hearing before production can start. The current construction licence remains valid until February 2031.
The CNSC concluded that the project is not expected to cause significant adverse environmental effects, provided that Denison implements the required mitigation measures, monitoring programmes and follow-up activities.
The conditions also include continued engagement with affected Indigenous nations and local communities.
Phoenix is the first major Canadian uranium mine to receive construction approval in more than 20 years. Denison also describes it as Canada’s first new large-scale uranium mine since Cigar Lake, which entered production in 2014.
Project cost rises to CAD600 million
Following the final investment decision, the estimated construction cost stands at approximately CAD600 million. This is around 20 per cent above the inflation-adjusted estimate in the project’s 2023 feasibility study.
Denison attributes the increase to inflation, more detailed engineering and technical modifications.
Among the changes, a larger number of wells will be designed for use in both injection and recovery. This will provide greater flexibility when controlling the underground flow of the mining solution.
In addition to the construction budget, approximately CAD 100 million is estimated to have been spent on engineering, procurement, and other activities before the final investment decision.
Denison expects construction to take approximately 24 months and is targeting first uranium production in mid-2028.
The economic assessment is based on around 10 years of production, with extraction continuing during part of an additional calendar year.
Phoenix contains proven and probable reserves of 56.7 million pounds of uranium oxide, equivalent to approximately 21,800 tonnes of uranium.
The project’s importance is reinforced by Canada’s position in the global uranium market. The country produced 14,300 tonnes of uranium in 2024, accounting for approximately 24 percent of worldwide mine production.
All of Canada’s current uranium production comes from Saskatchewan.
Phoenix is therefore more than another mining development. If the technology performs as planned, it could open the way for ISR extraction at other Canadian deposits previously considered too complex or expensive for conventional mining methods.