Denison Mines (NYSE: DNN) begins full-scale Phoenix ISR uranium build
Rhea-AI Filing Summary
Denison Mines Corp. reports that work at its Phoenix In-Situ Recovery (ISR) uranium mine, part of the Wheeler River project in Saskatchewan, has moved from site preparation to full-scale construction, including the start of installation of the Phase 1 perimeter freeze wall.
Early works since March 2026 have completed substantial site clearing, schedule-sensitive civil works and construction management facilities. Temporary camp facilities have boosted accommodation capacity at Wheeler River to nearly 400 people. The company estimates that over 20% of overall site civil work is complete and civil subgrade work for the process plant and wellfield areas is near 100%, ahead of schedule-critical concrete pours expected to begin in August and around-the-clock activity with a second shift.
Wheeler River, described as the largest undeveloped uranium project in the eastern Athabasca Basin, is a joint venture between Denison (90%, operator) and JCU (10%), with Denison holding an effective 95% interest. The Phoenix ISR operation received provincial Environmental Assessment approval in July 2025 and federal Environmental Assessment approval plus a construction licence in February 2026, enabling full-scale construction to commence in July 2026.
Positive
- Full-scale construction has begun at the Phoenix ISR uranium mine, marking a major development milestone for Denison’s flagship Wheeler River project following key environmental and construction approvals.
Negative
- None.
Key Figures
On-site camp capacity: nearly 400 people
Site civil work completed: +20%
Civil subgrade completion: near 100%
+5 more
8 metrics
On-site camp capacity
nearly 400 people
Accommodation capacity at the Wheeler River property after temporary camp installation
Site civil work completed
+20%
Estimated portion of overall site civil work completed during the early works program
Civil subgrade completion
near 100%
Civil subgrade work for the process plant and wellfield areas at Phoenix
Wheeler River joint venture interest
Denison 90%; JCU 10%
Ownership interests in the Wheeler River uranium project
Effective Wheeler River interest
95%
Denison’s effective interest in its flagship Wheeler River Project
Athabasca Basin land position
~457,000 hectares
Direct ownership interests in properties in the Athabasca Basin region
Phoenix EA provincial approval
July 2025
Environmental Assessment approval by the Province of Saskatchewan
Phoenix construction licence
February 2026
EA approval and construction licence grant by the Canadian Nuclear Safety Commission
Key Terms
In-Situ Recovery, Environmental Assessment, NI 43-101 Technical Report, toll milling agreement, +2 more
6 terms
In-Situ Recovery technical
"activities at the Phoenix In-Situ Recovery (“ISR”) uranium mine have transitioned"
In-situ recovery is a mining method that extracts a valuable material by dissolving it underground and pumping the solution to the surface instead of digging or blasting rock. For investors, it matters because this approach often lowers upfront construction costs, shortens development time and reduces visible land disturbance, but it also brings regulatory, environmental and groundwater risks that can affect project timelines, operating costs and valuation.
Environmental Assessment regulatory
"culminating in the July 2025 approval of the Project’s Environmental Assessment"
An environmental assessment is a process that evaluates how a project or activity might impact the natural surroundings, such as air, water, land, and wildlife. It helps identify potential environmental risks and ensures that any negative effects are managed or minimized. For investors, this assessment provides insight into the sustainability and long-term viability of projects, which can influence their financial decisions and risk management.
NI 43-101 Technical Report financial
"the technical report titled “NI 43-101 Technical Report on the Wheeler River Project"
A NI 43-101 technical report is a standardized, legally required study used in Canada that describes a mining project’s geology, exploration work, and estimates of how much mineral or ore might exist. Think of it as an independent inspector’s blueprint that explains the data, methods, and uncertainties behind those estimates so investors can judge how reliable the claims are and compare projects on a consistent basis.
toll milling agreement financial
"to process the ore from the Cigar Lake mine under a toll milling agreement"
A toll milling agreement is a contract where one company pays a processor to grind, mill or otherwise transform its raw materials into finished or semi‑finished products while the material owner keeps legal title and pays a fee for the service. For investors it matters because it lets a business avoid buying expensive production plants, affecting costs, margins, supply‑chain risk and operational flexibility—like renting a specialized workshop instead of owning it.
Pre-Feasibility Study technical
"a cost update to the 2018 Pre-Feasibility Study for conventional underground mining"
A pre-feasibility study is an initial assessment that evaluates whether a proposed project or investment idea is worth exploring further. It involves examining basic factors like costs, potential benefits, and possible challenges, similar to conducting a preliminary check before deciding to invest more time and resources. This helps investors determine if pursuing the project further is practical and likely to be successful.
construction licence regulatory
"approval of the Project’s EA and the grant of the construction licence"
A construction licence is an official government or municipal permit that authorizes a company to build, expand or alter a physical project, often with specific conditions, inspections and time limits. For investors it matters because the licence controls whether and when a project can proceed, affects costs and timelines, and creates legal risk—similar to needing a permit before starting a major renovation, without which the project can be delayed, fined or stopped.
AI-generated analysis. How Rhea-AI works. Not financial advice.
FAQ
What did Denison Mines (DNN) announce about the Phoenix ISR uranium project?
Denison announced that activities at the Phoenix ISR uranium mine have shifted from site preparation to full-scale construction, including starting installation of the Phase 1 perimeter freeze wall after completing critical civil works and support infrastructure.
How advanced is construction work at Denison’s Phoenix project (DNN)?
Denison estimates that over 20% of overall site civil work is complete, with civil subgrade work for the process plant and wellfield areas near 100%, positioning the project for schedule-critical concrete pours and accelerated construction through a second work shift.
What ownership interest does Denison Mines (DNN) hold in the Wheeler River project?
Wheeler River is a joint venture between Denison and JCU, with Denison holding 90% and acting as operator, and JCU holding 10%. Denison describes its effective interest in the flagship Wheeler River Project as 95%.
Which regulatory approvals has Denison (DNN) secured for the Phoenix ISR mine?
The Phoenix ISR operation obtained Environmental Assessment approval from Saskatchewan in July 2025 and received Environmental Assessment approval and a construction licence from the Canadian Nuclear Safety Commission in February 2026, enabling the start of full-scale construction in July 2026.
What workforce capacity does Denison’s Wheeler River camp now support?
After installing and commissioning temporary construction camp facilities, Denison states that accommodation capacity at the Wheeler River property has been increased to nearly 400 people, allowing a ramp-up of the on-site workforce and the introduction of a second construction shift.
Where are Denison Mines’ (DNN) other key uranium interests located?
Denison focuses on the Athabasca Basin in northern Saskatchewan, holding a 22.5% interest in the McClean Lake Joint Venture, 25.17% in the Midwest Joint Venture, and 70.55% in the THT and Huskie deposits, plus properties covering about 457,000 hectares.
What risks and uncertainties does Denison (DNN) highlight for Phoenix and Wheeler River?
Denison notes that technical study results and cost forecasts may change and that work could be affected by access to equipment, staffing, contractors, capital funding, joint venture and regulatory approvals, with outcomes potentially differing materially from current expectations.
UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
FORM 6-K
REPORT OF FOREIGN PRIVATE ISSUER PURSUANT TO RULE
13a-16 OR 15d-16
UNDER THE SECURITIES EXCHANGE ACT OF 1934
Date: July 28, 2026
Commission File Number: 001-33414
Denison Mines Corp.
(Name of
registrant)
1100-40 University Avenue
Toronto Ontario
M5J 1T1 Canada
(Address of
principal executive offices)
Indicate by check mark whether the registrant files
or will file annual reports under cover Form 20-F or Form
40-F.
Form
20-F ☐ Form 40-F ☒
Indicate by check mark if the registrant is submitting the
Form 6-K in paper as permitted by Regulation S-T Rule
101(b)(1): ☐
Indicate by check mark if the registrant is submitting the
Form 6-K in paper as permitted by Regulation S-T Rule
101(b)(7): ☐
SIGNATURES
Pursuant to the requirements of the Securities Exchange Act
of 1934, the registrant has duly caused this report to be signed on
its behalf by the undersigned, thereunto duly
authorized.
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DENISON MINES
CORP.
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/s/ Amanda Willett
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Date: July 28, 2026
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Amanda
Willett
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Vice
President Legal and Corporate Secretary
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FORM 6-K
EXHIBIT INDEX
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Exhibit Number
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Description
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99.1
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Press release dated July 28, 2026 |
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Exhibit 99.1
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Denison Mines
Corp.
1100 – 40
University Ave
Toronto, ON M5J
1T1
www.denisonmines.com
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PRESS RELEASE
Denison Announces Completion of Site Preparation
Activities
and Commencement of Full-Scale Construction at Phoenix ISR Uranium
Mine
Toronto, ON – July 28,
2026. Denison Mines Corp. (“Denison” or the
“Company”) (TSX: DML, NYSE American: DNN) is pleased to
announce that activities at the Phoenix In-Situ Recovery
(“ISR”) uranium mine (“Phoenix” or the
“Project”) have transitioned from site preparations to
full-scale construction, including initiation of the perimeter
freeze wall installation for Phase 1 of the
mine.
Since
the commencement of site preparation and early works in March 2026,
significant progress has been made by Denison and its construction
partners to complete several critical site preparation activities
– including substantial completion of site clearing
activities, advancement of schedule-sensitive site civil works, and
the establishment of construction management facilities.
Preparation activities also involved the installation and
commissioning of temporary construction camp facilities, which
significantly increases the accommodation capacity of the Wheeler
River property to nearly 400 people and allows a ramp-up in the
on-site workforce.
Additionally,
aggregate production required for various site civil purposes
continues at a nearby quarry, and the concrete batch plant has been
mobilized to site. Schedule-critical concrete-related activities
for the substation and the main process plant foundations are
currently expected to commence in August.
David Cates,
President & CEO of Denison, commented, “Completing the
site-preparation activities needed to ramp up our on-site workforce
and achieve a full-scale rate of construction is an important
initial milestone for the Phoenix project.
Site civil work has progressed well during the early works program,
with +20% of overall site civil work estimated
to be completed to date. Importantly, we have achieved near 100%
completion of civil subgrade work for the process plant and
wellfield areas, which is needed to facilitate the planned concrete
pour for the plant and the initiation of the freeze wall
installation program.
Construction activity is expected to accelerate through the
remainder of the summer months with the commencement of a second
shift, which means seasonally sensitive civil and other
construction work can continue virtually 24-hours a day in support
of the completion of our key first-year construction milestones
– including concrete pours of the foundations for the process
plant and main power transformer, installation of the freeze wall,
as well as earth works for the airstrip and on-site power
distribution.
Achieving these positive early results demonstrates the readiness
and commitment of Denison and our construction partners as we
advance this unique nation-building project to become
Canada’s first new large-scale uranium mine since Cigar
Lake.”
About Wheeler River
Wheeler River is the largest undeveloped uranium project in the
infrastructure-rich eastern portion of the Athabasca
Basin region, in northern Saskatchewan. Wheeler River is host to
the high-grade Phoenix and Gryphon uranium deposits, discovered by
Denison in 2008 and 2014, respectively, and is a joint venture
between Denison (90% and operator) and JCU (Canada) Exploration
Company Limited (“JCU”, 10%). In August 2023, Denison
filed a technical report (the “Wheeler River Report”)
summarizing the results of (i) Phoenix Feasibility Study; and (ii)
a cost update to the 2018 Pre-Feasibility Study for conventional
underground mining of the basement-hosted Gryphon uranium deposit.
Based on the respective studies, both deposits have the potential
to be competitive with the lowest cost uranium mining operations in
the world. Permitting efforts for the planned Phoenix ISR operation
commenced in 2019, culminating in the July 2025 approval of the
Project’s Environmental Assessment (“EA”) by the
Province of Saskatchewan and the February 2026 approval of the
Project’s EA and the grant of the construction licence by the
Canadian Nuclear Safety Commission. Full-scale construction
commenced for Phoenix in July 2026. More information is available
in the technical report titled “NI 43-101 Technical Report on
the Wheeler River Project Athabasca Basin, Saskatchewan,
Canada” dated August 8, 2023 with an effective date
of June 23, 2023, and an update to estimated Phoenix initial
capital costs described in Denison’s Annual Information Form
dated March 30, 2026, copies of which are available on
Denison’s website and under its profile on SEDAR+ at
www.sedarplus.ca and on EDGAR
at www.sec.gov/edgar.
About Denison
Denison is a leading uranium exploration and development company
with interests focused in the Athabasca Basin region of northern
Saskatchewan, Canada. In addition to Denison’s effective 95%
interest in its flagship Wheeler River Project, Denison's interests
in Saskatchewan include a 22.5% ownership interest in the McClean
Lake Joint Venture ("MLJV"), which includes uranium deposits (with
mining at the McClean North deposit having commenced in 2025 using
the MLJV's SABRE mining method) and the McClean Lake uranium mill
(currently utilizing a portion of its licensed capacity to process
the ore from the Cigar Lake mine under a toll milling agreement),
plus a 25.17% interest in the Midwest Joint Venture Midwest Main
and Midwest A deposits, and a 70.55% interest in the Tthe Heldeth
Túé ("THT") and Huskie deposits on the Waterbury Lake
Property. The Midwest Main, Midwest A, THT and Huskie deposits are
located within 20 kilometres of the McClean Lake mill. Taken
together, Denison has direct ownership interests in properties
covering ~457,000 hectares in the Athabasca Basin
region.
Additionally, through its 50% ownership of JCU (Canada) Exploration
Company, Limited (“JCU”), Denison holds interests in
various uranium project joint ventures in Canada, including the
Millennium project (JCU, 30.099%), the Kiggavik project (JCU,
33.8118%) and Christie Lake (JCU, 34.4508%).
In 2024, Denison celebrated its 70th year in uranium mining,
exploration, and development, which began in 1954 with
Denison’s first acquisition of mining claims in the Elliot
Lake region of northern Ontario.
For more information, please contact
David
Cates
(416) 979-1991 ext.
362
President and
Chief Executive Officer
Geoff Smith
(416) 979-1991 ext. 358
Vice
President Corporate Development & Commercial
Follow Denison on Twitter
@DenisonMinesCo
CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING
STATEMENTS
Certain information contained in this news release
constitutes 'forward-looking information', within the meaning of
the applicable United States and Canadian legislation, concerning
the business, operations and financial performance and condition of
Denison. Generally, these forward-looking statements can be
identified by the use of forward-looking terminology such as
'potential', 'plans', 'expects', 'budget', 'scheduled',
'estimates', 'forecasts', 'intends', 'anticipates', or 'believes',
or the negatives and/or variations of such words and phrases, or
state that certain actions, events or results 'may', 'could',
'would', 'might' or 'will' 'be taken', 'occur' or 'be achieved'. In
particular, this news release contains forward-looking information
pertaining to Denison's current expectations, intentions and
objectives with respect to Wheeler River and Phoenix, including the
Company's outlook generally with respect to ISR mine
development and operations, and milestones related thereto, for
Phoenix.
Forward
looking statements are based on the opinions and estimates of
management as of the date such statements are made, and they are
subject to known and unknown risks, uncertainties and other factors
that may cause the actual results, level of activity, performance
or achievements of Denison to be materially different from those
expressed or implied by such forward-looking statements. For
example, the results and underlying assumptions and interpretations
of its technical studies and cost forecasting may not be maintained
after further testing, procurement, or operations, or be
representative of actual conditions at the Project or within the
applicable deposits. In addition, Denison may decide or otherwise
be required to discontinue work if it is unable to maintain or
otherwise secure the necessary resources (such as equipment,
staffing, contractors, testing facilities, capital funding, joint
venture approvals, regulatory approvals, etc.). Denison believes
that the expectations reflected in this forward-looking information
are reasonable but no assurance can be given that these
expectations will prove to be accurate and results may differ
materially from those anticipated in this forward-looking
information. For a discussion in respect of risks and other factors
that could influence forward-looking events, please refer to the
factors discussed in Denison's Annual Information Form dated March
30, 2026 under the heading 'Risk Factors' or in subsequent
quarterly financial reports. These factors are not, and should not
be construed as being, exhaustive.
Accordingly,
readers should not place undue reliance on forward-looking
statements. The forward-looking information contained in this news
release is expressly qualified by this cautionary statement. Any
forward-looking information and the assumptions made with respect
thereto speaks only as of the date of this news release. Denison
does not undertake any obligation to publicly update or revise any
forward-looking information after the date of this news release to
conform such information to actual results or to changes in
Denison's expectations except as otherwise required by applicable
legislation.
Figure 1. Phoenix ISR Mine, Site Preparation Progress as of April
30, 2026
Figure 2. Phoenix ISR Mine, Civil Works for Wellfield, Process
Plant, and Substation Areas as of July 21, 2026
Figure 3. Temporary Construction Camp Facilities Installation
Progress at the Phoenix Site as of July 6, 2026
Figure 4. Airstrip Site Preparation (Phoenix site in the distances)
as of July 25, 2026
