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Corporate History

The Denison of today is the result of a series of strategic acquisitions, amalgamations and divestitures by its predecessor companies.  The history of Denison can be tracked to:

  • 1954:  the incorporation of Consolidated Denison Mines Limited
  • 1960:  formation of Denison Mines Limited, upon amalgamation with Can-Met Exploration Limited
  • 1992:  closure of the Denison and Stanrock uranium mines

The Denison Mine was the longest continuous uranium mining operation in the Elliot Lake, Ontario area, with operations running from 1957 to 1992, during which time it produced 69 million tonnes of ore.

1993:  The McClean Lake Joint Venture (“MLJV”) was established, and Denison obtained its 22.5% interest in the McClean Lake project.

1995:  Development of the McClean Lake project began, with mill construction. Mining operations occurred on several deposits from 1996 to 2008:  JEB (1996 to 1997), Sue C (1997 to 2002), Sue A (2005 to 2006), Sue E (2005 to 2008) and Sue B (2007 to 2008).

1997:  Denison formed its Denison Environmental Services division in 1997 to provide mine decommissioning and mine care and maintenance services to industry and government, as well as to manage Denison’s post mine closure environmental obligations on its Elliot Lake landholdings.  To-date, the Closed Mines group remains focused on post-closure mine care and maintenance services, and its technical team is principally located in Elliot Lake, Ontario.

1999:  McClean Lake ore processing activities reached commercial production and operated until the end of June 2010, producing approximately 50 million pounds U3O8,

2004:  Preliminary study work began by the MLJV, on what would become the Surface Access Borehole Resource Extraction (“SABRE”) mining program.

2006:  The formation of the modern corporate Denison, when International Uranium Corp. acquired Denison by plan of arrangement and changed its name to Denison Mines Corp.

2012:  Denison sold its US Mining Division, which included 100% ownership of the White Mesa Mill in Utah, to Energy Fuels Inc.

2013:  Denison acquired JNR Resources Inc., Fission Energy Corp. and Rockgate Capital Corp. (“Rockgate”)

2014:  The McClean Lake mill re-commenced operations with the delivery of ore shipments from the Cigar Lake Mine, owned by the Cigar Lake Joint Venture and operated by Cameco under a toll milling agreement.

2015:  Denison sold its interest in the Gurvan Saihan joint venture in Mongolia to Uranium Industry a.s.

2016:  McClean Lake mill expansion was completed and an increase to the licensed capacity of the mill was approved – resulting in an increase to the licensed production capacity of the mill to 24 million pounds U3O8 per year. This increased licensed capacity allowed for the processing of 100% of ore production from the Cigar Lake mine, up to 18 million pounds U3O8 per year, and provides the flexibility for the mill to process ore from other sources in the future.

2016:  Denison sold its subsidiary Rockgate, which had been reorganized to hold Denison’s varied uranium mineral interests in Zambia, Mali and Namibia, to GoviEx Uranium Inc.

2017:  Denison increased its interest in its flagship Wheeler River project, to approximately 66%

2017-2019:  Denison executed a series of Memoranda of Understanding in support of the Wheeler River project with certain Indigenous communities who assert that Wheeler River falls partially or entirely within their traditional territories and where traditional land use activities are currently practiced within the local and regional area surrounding the project. These non-binding MOUs formalize the signing parties’ intent to work together in the spirit of mutual respect and cooperation, in order to collectively identify practical means by which to avoid, mitigate, or otherwise address potential impacts of the project upon the exercise of Indigenous rights, Treaty rights, and other interests, as well as to facilitate sharing in the benefits that are expected to flow from the Wheeler River project.

2018:  Denison acquired Cameco Corporation’s 24% in the Wheeler River project, increasing its interest to 90%, with the remaining 10% held by JCU (Canada) Exploration Limited (“JCU”).

2018:  Denison announced the results of the Pre-Feasibility Study for the Wheeler River project, highlighted by the selection of the in-situ recovery (“ISR”) mining method for the development of the high-grade Phoenix deposit.  The project is estimated to have mine production of 109.4 million pounds U3O8 over a 14-year mine life, with a base case pre-tax Net Present Value of $1.31 billion (8% discount rate), Internal Rate of Return of 38.7%, and initial preproduction capital expenditures of $322.5 million.

2019:  The Canadian Nuclear Safety Commissions and the Saskatchewan Ministry of Environment accepted the Provincial Technical Proposal and Federal Project Description submitted by Denison for the ISR uranium mine and processing plant proposed for the Wheeler River Project. This acceptance initiated the Environmental Assessment process for Wheeler River in accordance with the requirements of both the Canadian Environmental Assessment Act, 2012 and the Saskatchewan Environmental Assessment Act.

2020:  Denison announced the results of the Preliminary Economic Assessment for the Waterbury Lake property evaluating the potential use of the ISR mining method at the Tthe Heldeth Túé (“THT”) deposit.  The THT ISR operation is estimated to produce total mine production of 9.7 million pounds U3O8 (177,664 tonnes at 2.49% U3O8) over an approximate six year mine-life with final processing occurring at Denison’s 22.5% owned McClean Lake mill with a base case pre-tax NPV of $177 million (8% discount rate), IRR of 39.1%, and initial capital expenditures of $111.6 million, excluding pre-construction evaluation and development costs.

2021 – March:  Denison entered into a Participation and Funding Agreement and Letter of Intent with the English River First Nation (“ERFN”) in connection with the advancement of the proposed ISR mining operation at Wheeler River, as well as an Exploration Agreement in respect of Denison’s exploration and evaluation activities within the ERFN traditional territories. These agreements reflect Denison’s desire to operate its business in a progressive and sustainable manner that respects ERFN rights and advances reconciliation with Indigenous peoples. The agreements provide ERFN with economic opportunities and other benefits, and establish a foundation for future collaboration in an authentic, cooperative, and respectful way

2021 - March:  Denison announced its inclusion in the S&P/TSX Composite Index – the headline index for the Canadian equity market – effective prior to the open of trading on Monday March 22, 2021.

2021 - March:  Denison completed a strategic acquisition of 2.5 million pounds U3O8, at a weighted average price of US$29.66 per pound U3O8 (including purchase commissions of US$0.04 per pound U3O8) and a total cost of approximately US$74.15 million.  The uranium spot price appreciated to US$42.00 per pound U3O8 by December 31, 2021, resulting in a fair value gain on Denison’s physical uranium holdings of approximately $41.4 million for the year ended December 31, 2021.

2021 - August:  Denison acquired 50% of JCU, with the other 50% held by UEX Corporation, thereby increasing its effective interest in the Wheeler River project to 95%.  Through its 50% ownership of JCU, Denison holds additional interests in various uranium project joint ventures in Canada, including the Millennium project (JCU 30.099%), the Kiggavik project (JCU 33.8123%) and Christie Lake (JCU 34.4508%).

2021 - November:  Denison announced the MLJV’s completion of a SABRE test mining program at McClean North.  The SABRE field test ran safely from May to September 2021 with four cavities mined and the recovery of approximately 1,500 tonnes of high-value ore ranging in grade from 5% to 16% U3O8. The program was concluded successfully with no safety, environmental or radiological incidents. Importantly, key operating objectives associated with the test program – including targets for cavity diameter, rates of recovery, and mine production rates – were all achieved during the field test.

2021 - December:  Denison formally adopted an Indigenous Peoples Policy, which reflects the Company’s recognition of the important role of Canadian business in the process of reconciliation with Indigenous peoples in Canada and outlines the Company’s commitment to take action towards advancing reconciliation.

2022 - January:  The CNSC approved the amendment to the Mine Operating License for the McClean Lake operation to further extend the capacity and life of the tailings management facility.  

2022 - June: Denison and Kineepik Métis Local #9 (“KML”) entered into a Participation and Funding Agreement (the “KML PFA”), which expresses Denison’s and KML’s mutual commitment to the co-development of an agreement supporting the advancement of the Phoenix ISR project. The KML PFA builds on an existing letter agreement between Denison and KML with respect to the support of KML’s contributions to, and participation in, the Federal and Provincial EA process. The parties also entered into an Exploration Agreement (the “KML Exploration Agreement”) in respect of Denison’s exploration and evaluation activities within KML’s land and occupancy area. These agreements reflect Denison’s commitment to the principles set out in the Company’s Indigenous People’s Policy and advancing reconciliation through taking action.

2022 - August: Denison announced it had obtained all necessary permitting to conduct the planned ISR feasibility field test (“FFT”) at the Phoenix deposit at Wheeler River, designed to provide further verification of the permeability, leachability, and containment parameters needed for the successful application of the ISR mining method at Phoenix.

2022 - October: Denison entered into an exploration agreement (the “YNLRO Exploration Agreement”) with the Ya’thi Néné Lands and Resources Office (“YNLRO”), Hatchet Lake Denesułiné First Nation, Black Lake Denesułiné First Nation, Fond du Lac Denesułiné First Nation (collectively, the “Athabasca Nations”) and the Northern Hamlet of Stony Rapids, the Northern Settlement of Uranium City, the Northern Settlement of Wollaston Lake and the Northern Settlement of Camsell Portage (collectively, the “Athabasca Communities”) in respect of Denison’s exploration and evaluation activities within the traditional territory of the Athabasca Nations.

2022 - October: Denison achieved a significant regulatory milestone for Wheeler River with the submission of the draft Environmental Impact Statement to the Saskatchewan Ministry of Environment and the CNSC. The EIS submission outlines the Company’s assessment of the potential effects, including applicable mitigation measures, of the proposed ISR uranium mine and processing plant planned for Wheeler River, and reflects several years of baseline environmental data collection, technical assessments, plus extensive engagement and consultation with Indigenous and non-Indigenous interested parties.

2022 - November: Denison announced the highlights of the highly successful leaching phase of the FFT conducted at the Phoenix deposit at Wheeler River:

  • Recovered approximately 14,400 pounds of U3O8 over ten days of active leaching following completion of initial acidification of the leaching area;
  • Returned maximum uranium head grade of recovered solution of 43 grams per litre ('g/L') when the leaching phase of the FFT was completed, with grades still rising (indicative of the ramp-up segment of a well production profile);
  • Achieved suitable acidification for ISR mining within 7 days post initial injection at 5 metre well spacing and within 17 days for 10 metre well spacing;
  • Demonstrated the ability to achieve and maintain uranium mass flow rate consistent with the assumptions in the 2018 Pre-Feasibility Study;
  • Further demonstrated hydraulic control of injected solution during the FFT, reporting no responses in the monitoring wells outside of the designed FFT test area; and
  • Confirmed breakthrough times between injection and recovery wells, consistent with the Project's hydrogeological model and the previously completed tracer test.

2022 - December: Denison reported the results from long-term core leach metallurgical testing completed to further support the establishment of ISR production and recovery curves to be used in the feasibility study for the project. The Company completed a long-term test of a representative intact core sample using specialized equipment to replicate the in-situ leaching conditions of the Phoenix deposit. The results were highlighted by: (a) overall recovery of uranium in excess of 97% – demonstrating excellent recovery of uranium from intact high-grade core without the use of permeability enhancement; (b) average recovered solution uranium head grade of 18.3 g/L – exceeding the assumed 15 g/L uranium head grade being used in FS plant designs; (c) continuous intact core leach testing over a period of 377 days, with uranium recovery head grades consistently maintained above 5 g/L during the final stages of the production curve and then declining during the ramp-down stage; and (d) maximum recovered solution uranium head grade of 49.8 g/L achieved using similar lixiviant concentrations as to those used during the FFT.

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