Tag Archives: Denison Mines


Wood Canada to carry out detailed design engineering for Phoenix ISR uranium deposit

Denison Mines Corp has selected Wood Canada to complete the detailed design engineering for the in-situ recovery (ISR) mining project planned for Denison’s flagship Phoenix uranium deposit in the Athabasca Basin of Saskatchewan, Canada.

Part of the global consulting and engineering firm Wood PLC, Wood Canada previously completed an NI 43-101 feasibility study in 2023 to evaluate the use of the ISR mining method at Phoenix.

Phoenix and the nearby Gryphon uranium deposit are part of the Wheeler River uranium project, which is the largest undeveloped uranium mining project in the infrastructure-rich eastern portion of the Athabasca Basin region in northern Saskatchewan, Canada, according to Denison. Denison has an effective 95% ownership interest in Wheeler River and is the project operator.

The results of the Phoenix feasibility study reflected several years of technical de-risking efforts successfully completed by Denison and demonstrated a base-case after-tax (adjusted) economics – including a net present value of C$1.56 billion ($1.16 billion, 100% basis) and an internal rate of return of 90% assuming uranium selling prices in the range of $66.53-$70.11/Ib U3O8.

Following completion of this study, Denison’s Board of Directors approved the continuation of efforts to advance Phoenix towards a final investment decision and, in late 2023, the Management Committee of the Wheeler River joint venture approved a budget for the applicable 2024 expenditures. Detailed engineering design constitutes a significant portion of the work remaining to advance Phoenix to the point where a decision can be made to proceed to construction and, ultimately, production.

Kevin Himbeault, Denison’s Vice President of Operations, said: “In recognition of Wood’s performance leading the Phoenix feasibility study, competitive pricing and alignment with our bid evaluation process, we are pleased to announce the award of a detailed design engineering contract to Wood. Maintaining continuity through completion of the Phoenix feasibility study, front-end engineering design and detailed design allows us to build on our combined knowledge and working relationship to deliver an engineering package that will ultimately support the construction and operation of the first ISR uranium mining operation in the Athabasca Basin.”

The scope of the facilities to be designed by Wood under this contract includes (i) site civil earthworks and distribution of utility piping throughout the main project site, (ii) electrical power distribution on site, (iii) surface piping and services for the mine wellfield, (iv) the process plant and related infrastructure, (v) operations complex, (vi) maintenance and related buildings, (vii) metallurgical and analytical laboratories and (viii) site-wide communications systems.

Based on the currently anticipated scopes of work, the detailed design engineering contract with Wood is estimated to be up to approximately C$16 million in value, with the scope of work planned to commence in Q1’2024 and to potentially continue into H1’2025.

Wood to investigate ISR potential of Phoenix uranium deposit in Wheeler River JV FS

Denison Mines Corp says it has selected engineering firm Wood PLC to lead and author a feasibility study for the in-situ recovery (ISR) mining operation proposed for the Phoenix uranium deposit in the Athabasca Basin of Canada, part of the Wheeler River Joint Venture (WRJV) project.

The completion of the study is, Denison says, a critical step in the progression of the project and is intended to advance de-risking efforts to the point where the company and the WRJV will be able to make a definitive development decision.

Denison has an effective 95% ownership interest in Wheeler River (90% directly, and 5% indirectly through a 50% ownership in JCU), which has combined indicated mineral resources of 132.1 MIb of U3O8 (1.8 Mt at an average grade of 3.3% U3O8), plus combined inferred mineral resources of 3 MIb of U3O8 (82,000 t at an average grade of 1.7% U3O8).

Key objectives of the study are expected to include:

  • Environmental stewardship: extensive planning and technical work undertaken as part of the ongoing Environmental Assessment (EA), including applicable feedback from consultation efforts with various interested parties, is expected to be incorporated into the feasibility study project designs to support Denison’s aspiration of achieving a superior standard of environmental stewardship that meets and exceeds the anticipated environmental expectations of regulators and aligns with the interests of local Indigenous communities;
  • Updated estimate of mineral resources: mineral resources for Phoenix were last estimated in 2018. Since then, additional drilling has been completed in and around the Phoenix deposit as part of various ISR field tests, including drill hole GWR-045 (22% eU3O8 over 8.6 m), and exploration drilling. The updated mineral resource estimate will form the basis for mine planning in the study;
  • Mine design optimisation: feasibility study mine design is expected to reflect the decision to adopt a freeze wall configuration for containment of the ISR well field, as well as the results from multiple field test programs and extensive hydrogeological modelling exercises, which have provided various opportunities to optimise other elements of the project – including well pattern designs, permeability enhancement strategies, and both construction and production schedules;
  • Processing plant optimization: feasibility study process plant design is expected to reflect the decision to increase the ISR mining uranium head-grade to 15 g/L, as well as the results from extensive metallurgical laboratory studies designed to optimize the mineral processing aspects of the project; and
  • Class 3 capital cost estimate: the feasibility study is also intended to provide the level of engineering design necessary to support a Class 3 capital cost estimate (AACE international standard with an accuracy of -15% /+25%), which is expected to provide a basis to confirm the economic potential of the project highlighted in the prefeasibility study completed in 2018.

The 2018 prefeasibility study considered the potential economic merit of developing the Phoenix deposit as an ISR operation and the Gryphon deposit as a conventional underground mining operation. Taken together, the project was estimated to have mine production of 109.4 Mib of U3O8 over a 14-year mine life.

David Cates, Denison’s President & CEO, said: “The ISR de-risking activities we’ve completed since the publication of the prefeasibility study for Wheeler River in 2018 have been designed to support the completion of a future feasibility study, and the results to date have further confirmed the technical viability of the project – leading to the decision to advance the project and initiate the formal feasibility study process.

“During this de-risking phase, we have been able to verify orebody permeability and the leachability of high-grade uranium in conditions representative of an ISR mining setting. We’ve also engineered an improved containment design using a more conventional ground freezing approach. Based on the results of field programs and metallurgical lab testing completed over the last three years, we are confident that the project is ready to advance into a full feasibility study. Taken together with the selection of globally recognised engineering firm Wood, the decision to launch the formal feasibility study process for Phoenix represents another important step towards achieving our objective of bringing low-cost ISR mining to the high-grade uranium deposits of the Athabasca Basin.”

Denison Mines aims to bring ISR mining to Athabasca Basin uranium sector

The prefeasibility study on Denison Mines’ Wheeler River uranium project, in the Athabasca Basin of Canada, has brought with it a significant change in the mining process for the high-grade Phoenix deposit.

Denison is now considering the use of in-situ recovery (ISR) mining at Phoenix, a lower cost method than the previously considered jet bore system, which requires freeze wall protection and is used at Cameco’s Cigar Lake mine.

The PFS envisages co-developing both the Phoenix and Grypon deposits using two different mining methods. The former would use ISR, with the latter using conventional long-hole underground mining.

Taken together, the project is estimated to produce 7.8 MIb/y of U3O8 over a 14-year mine life, with a base case pre-tax net present value (8% discount rate) of C$1.31 billion ($1.01 billion), and initial pre-production capital expenditures of C$322.5 million.

This is based on a probable reserve of 109.4 MIb averaging 3.5% U3O8. Of this amount, 59.7 MIb comes from Phoenix, which has an average grade of 19.1% U3O8.

David Cates, President and CEO of Denison, said: “The selection of ISR mining for the high-grade Phoenix deposit is a defining moment for our company and a potentially transformational development for the future of uranium mining in the Athabasca Basin – bringing the world’s lowest cost uranium mining method to the jurisdiction hosting the world’s highest-grade uranium deposits.”

Denison said the selection of ISR mining at Phoenix came after considering 32 alternate mining methods to replace the high-cost jet bore mining system assumed for the Phoenix deposit in the 2016 preliminary economic assessment.

“The suitability of ISR mining for Phoenix has been confirmed by significant work completed in the field and laboratory – including drill hole injection, permeability, metallurgical leach, agitation, and column tests,” the company said.

Results demonstrated high rates of recovery in both extraction (+90%) and processing (98.5%) following a simplified flowsheet that precipitates uranium directly from the uranium bearing solution, without the added costs associated with ion exchange or solvent extraction circuits, Denison added.

“Given the unique geological setting of the Phoenix deposit, straddling the sub-Athabasca unconformity in permeable ground, the project development team has combined the use of existing and proven technologies from ISR mining, ground freezing, and horizontal directional drilling to create an innovative model for in-situ uranium extraction in the Athabasca Basin.

“While each of the technologies are well established, the combination of technologies results in a novel mining approach applicable only to deposits occurring in a similar geological setting to Phoenix – which now represents the first deposit identified for ISR mining in the Athabasca Basin.”

Wheeler River is a joint venture between Denison (63.3% and operator), Cameco (26.7%), and JCU (Canada) Exploration Company (10%).

The PFS assumes initial construction activities will commence in 2021 and that first production will be achieved from the Phoenix operation by mid-2024. Initial construction is expected to commence at Gryphon by 2026 and first production from Gryphon is expected to be achieved in 2030.