The Wheeler River Uranium Project is located in the Athabasca Basin in Saskatchewan, Canada. In picture, triuranium octoxide. (Credit: Leiem/ Wikipedia)
The project involves the development of Phoenix and Gryphon uranium deposits. In picture, uranium ore. (Credit: IAEA Imagebank/Wikipedia)
Wheeler River site infrastructure layout (CNW Group/Denison Mines Corp.)

The Wheeler River Uranium Project is located in Saskatchewan, Canada. The project is regarded as the largest undeveloped uranium project situated in the eastern portion of the Athabasca Basin region in northern Saskatchewan.

The project involves the development of Phoenix and Gryphon uranium deposits.

Wheeler River is owned by Wheeler River Joint Venture (WRJV). Denison Mines holds 90% ownership interest in the WRJV, whereas JCU (Canada) Exploration Company owns the remaining 10%.

Denison, which has been the operator of the property since November 2004, also owns 50% of JCU.

The preliminary economic assessment (PEA) for the project was completed in 2016, while Pre-feasibility Study (PFS) of the Gryphon deposit was announced in 2018.

In June 2023, Denison announced the results of the Feasibility Study (FS) for In-Situ Recovery (ISR) mining of the Phoenix deposit and a cost update to the 2018 PFS.

The front-end engineering design (FEED) phase is expected to be completed by the end of 2023. Commercial production from the project is expected to begin in 2027 or 2028.

The total estimated mine life of the Phoenix deposit and Gryphon deposit is ten years and 6.5 years, respectively.

The initial capital cost for the Phoenix deposit is estimated to be C$419.4m ($310m) and C$737.4m ($546m) for Gryphon.

Wheeler River Project Location

The Wheeler River Uranium Project is located in a greenfield site in the eastern Athabasca Basin in northern Saskatchewan. The location is around 600km north of Saskatoon, 260km north of La Ronge and 100 km southwest of Points North landing.

The property comprises 19 contiguous mineral claims covering an area of 11,720ha.

The uranium project’s two deposits- Phoenix and Gryphon, were discovered in 2008 and 2014, respectively. The Gryphon deposit is located approximately 3km northwest of the Phoenix deposit.

Wheeler River lies in proximity to the provincial power grid and can be accessed by all-weather roads. It can use water from the numerous lakes and rivers in the area.

Geology and Mineralisation

The uranium project is located near the south-eastern margin of the Athabasca Basin, a broad, closed, and elliptically shaped cratonic basin.

The Phoenix deposit was classified as an unconformity-associated uranium deposit of the unconformity-hosted variety, while Gryphon is an unconformity-related deposit of the basement-hosted variety.

The Phoenix deposit is interpreted to be structurally controlled by the WS Shear, a prominent basement thrust fault which occurs footwall to a graphitic-pelite and hanging wall to a garnetiferous pelite and quartzite unit.

The mineralisation within the Phoenix deposit is dominated by massive to semi-massive uraninite associated with an alteration assemblage comprising hematite, dravitic tourmaline, illite and chlorite.

Mineralisation within the Gryphon deposit primarily features massive, semi-massive or fracture-hosted uraninite associated with an alteration assemblage comprising hematite, dravitic tourmaline, illite, chlorite and kaolinite.

Wheeler River Uranium Project Reserves

The Phoenix mineral resource estimate totals 280.2kt in measured and indicated categories at 11.4% Triuranium octoxide (U3O8) containing 70.5 Mlbs U3O8.

Proven and Probable mineral reserves at Phoenix deposit are estimated to be 56.7 million pounds U3O8. It is based on the aggregate mine feed to the plant and represents recovering 80.6% of total uranium available.

Using a cut-off grade of 0.2% U3O8, Gryphon deposit is estimated to contain Indicated mineral resources of 1.643 million tonnes, at a grade of 1.7% U3O8 for a total of 61.9 million pounds U3O8, plus Inferred mineral resources of 73,000 tonnes at a grade of 1.2% U3O8 for a total of 1.9 million pounds U3O8.

The deposit contains probable reserves of 49.7 million pounds U3O8 at 1.8% U3O8.

Phoenix Deposit Mining and Processing

The Phoenix deposit is expected to become the first uranium In-Situ Recovery (ISR) mining operation in the Athabasca Basin region.

A comprehensive field and laboratory test work has been carried out to de-risk the use of the ISR mining method.

The operations are divided into five phases which include a total of 74 extraction wells, 172 injection wells, and 22 monitoring wells.

According to the 2018 FS, a processing plant will be built on the Wheeler River site that will receive uranium bearing solution (UBS) from the wellfield and process it into a finished yellowcake product.

The processing plant will prepare an acidic lixiviant solution and transfer it to an injection solution handling system for distribution in the wellfield.

The solution is then injected through a series of wells to dissolve the uranium from the host rock.

Subsequently, UBS will be pumped to the surface via extraction / recovery wells.

The processing plant will remove the impurities in UBS such as iron (Fe) and radium (Ra). The final yellowcake product is dried and packaged before shipment.

The processing plant is expected to recover 96.5% of the uranium feed contained in UBS following a six-month ramp up period.

It is estimated that 56.2 million pounds U3O8 will be available for sale, representing a combined 99% recovery rate.

Gryphon Deposit Mining and Processing

According to the 2018 PFS, Gryphon will be developed as a conventional underground mine.

The plan proposes two underground mining methods- longitudinal and transverse long hole stoping with cemented rock backfill (CRF) or hydraulic fill.

The deposit will be accessed from surface via the production shaft and the ventilation shaft.

The mined stopes will be backfilled using a rockfill, cemented rockfill, and hydraulic fill combination.

Gryphon is expected to produce approximately 605 tonnes per day of ore and an average of 330 tonnes per day of waste rock.

Production from the Gryphon operation is planned to be processed at the 22.5% Denison-owned McClean Lake processing plant located in the north-eastern portion of the Athabasca Basin region.

The mill will require to undergo certain upgrades in order to process the volume of throughput expected from the Gryphon operation.

With a mine life of 6.5 years, the deposit is expected to have an annual average mine production of 7.6 million pounds U3O8.

Contractors Involved   

The Phoenix FS was completed by Wood Canada, WSP USA Environment and Infrastructure, SRK Consulting, and Newmans Geotechnique.

Engcomp Engineering and Computing Professionals, SLR International, Stantec Consulting and Hatch prepared the Gryphon Update.