Denison Announces Results from Midwest ISR Preliminary Economic Assessment, Including After-Tax NPV of $965 Million
Denison Mines Corp.
1100 – 40 University Ave
Toronto, ON M5J 1T1
www.denisonmines.com
PRESS RELEASE
Denison Announces Results from Midwest ISR Preliminary Economic
Assessment, Including After-Tax NPV of $965 Million
Toronto, ON – August 6, 2025. Denison Mines Corp. (“Denison” or the “Company”) (DML: TSX, DNN:
NYSE American) is pleased to report the results of the Preliminary Economic Assessment (“PEA”)
completed for In-Situ Recovery (“ISR”) mining of the Midwest Main uranium deposit (“Midwest Main”) at the
Company’s 25.17%-owned Midwest project (“Midwest”). The PEA outlines total ISR mine production (100%
basis) of 37.4 million pounds U 3O8 over an approximately 6- year mine life , resulting in annual average
production of nearly 6.1 million pounds U 3O8, an after -tax base-case NPV of $ 965 million, and after-tax
base-case IRR of 82.7%.
Midwest is a joint venture (“MWJV”) owned by Denison (25.17%) and Orano Canada Inc. (“Orano Canada”)
(74.83%), and is located approximately 25 kilometers, by existing roads, from the Denison (22.5%) and
Orano Canada (77.5%) owned McClean Lake uranium mill. Orano Canada is the operator of Midwest and
is part of the Orano Group, which is recognized as a leading international operator in the field of nuclear
materials, with activities including uranium mining, conversion, enrichment, and other fuel services.
David Cates, Denison’s President & CEO commented, “The Midwest PEA illustrates tremendous
technical and economic potential for ISR mining at Midwest Main. While preliminary in nature, the
study incorporates the findings of our 2023 and 2024 field test programs, which provided support
for key ISR criteria necessary for the application of the mining method and demonstrates the
potential for robust economics. The project is estimated to have an all -in cost of production
amongst the lowest cost uranium mines in the world, benefitting from a powerful combination of
low initial capital costs and low cash operating costs.
Denison has established itself as the industry leader in advancing the deployment of the ISR mining
method to high-grade uranium deposits in the Athabasca Basin region of northern Saskatchewan,
and we are pleased to have worked together with Engcomp to deliver this exciting result. We thank
our Joint Venture partner Orano for entrusting us to advance the MWJV’s efforts to evaluate ISR
mining at Midwest.”
Midwest PEA Highlights:
• Base case post-tax Net Present Value (“NPV”)(8%) of $965 million (100% basis) – with Denison’s
25.17% interest in the project equating to a base-case after-tax NPV8% of $243 million.
• Base case pre-tax NPV8% of $1.62 billion (100% basis).
• Robust base-case Internal Rate of Return (“IRR”) of 83% (post-tax) and 111% (pre-tax).
• Base-case indicative after-tax payback period of 9 months.
• Estimated annual mine production of 6.1 million pounds U 3O8 for total life of mine production of
37.4 million pounds U3O8 over an approximately 6-year mine life.
• Processing assumed to occur at the Orano-Denison owned McClean Lake mill, supporting modest
estimated initial capital costs of $ 254 million (100% basis) and yielding an impressive after -tax
NPV8% to initial capital cost ratio of 3.8 times.
• Denison’s share of estimated initial capital costs is approximately $64 million.
• Updated Midwest Main mineral resource estimate of 38.7 million pounds U3O8 in Indicated mineral
resources (510,000 tonnes @ 3.5 % U 3O8), plus 12.6 million pounds U 3O8 in Inferred mineral
resources (905,000 tonnes @ 0.64% U3O8).
The PEA is preliminary in nature, includes mineral resources that are considered too speculative
geologically to have the economic considerations applied to them that would allow them to be categorized
as mineral reserves, mineral resources that are not mineral reserves do not have demonstrated economic
viability, and there is no certainty that the PEA will be realized.
Midwest Main ISR Preliminary Economic Assessment
The PEA highlights that the ISR mining method has the potential to be a technically sound and economically
robust means to extract significant uranium production from the high-grade Midwest Main deposit with low
initial capital costs, a high rate of return, and rapid payback.
The assessment incorporates the results of the 2023 and 2024 ISR field de-risking programs completed by
Denison on behalf of the MWJV following the completion of an internal Conceptual Mining Study in early
2023, which considered the potential application of ISR mining to Midwest Main.
Engcomp Engineering & Computing Professionals (“Engcomp”), an independent engineering firm based in
Saskatoon, Saskatchewan, with expertise in uranium mine development studies, is the lead author of the
PEA, and incorporated contributions from Newmans Geotechnique, Petrotek Corporation, and Understood
Mineral Resources Ltd. All dollar amounts are stated in Canadian dollars, unless otherwise noted.
Key operating parameters and economic results from the PEA are presented in the tables below.
Table 1 – Summary of Key Midwest Main Operation Parameters (100% Basis)
Mine Life 6.14 years
Potentially Mineable Resources(1) 37.4 million lbs U3O8 (650,000 tonnes at 2.60% U3O8)
Annual Production (Average)(2) 6.1 million lbs U3O8
Initial Capital Costs $254 million
Average Cash Operating Cost $15.78 (USD$11.69) per lb U3O8
All-in Cost(3) $34.80 (USD$25.78) per lb U3O8
(1) See Table 3 below for additional information regarding estimated mineral resource. See Table 4 below for additional
information regarding initial capital costs.
(2) Based on the estimated number of pounds U3O8 to be produced over the life of the project divided by mine life.
(3) All-in cost is estimated on a pre-tax basis and includes all project operating costs, capital costs post-FID, and
decommissioning costs divided by the estimated number of pounds U3O8 to be produced.
Table 2 – Summary of Midwest Economic Analysis (100% Basis)
Uranium Selling Price USD$80/lb U3O8 (1)
Exchange Rate (CAD$:USD$) 1.35
Discount Rate 8%
Operating profit margin(2) 85.4%
Pre-tax NPV8%(3) $1.62 billion
Pre-tax IRR(3) 111.1%
Pre-tax payback period(4) ~6 months
Post-tax NPV8%(3) $964.7 million
Post-tax IRR(3) 82.7%
Post-tax payback period(4) ~9 months
(1) Price forecast is stated in constant (not-inflated) dollars.
(2) Operating profit margin is calculated as aggregate uranium revenue less aggregate operating costs, divided by
aggregate uranium revenue. Operating costs exclude all royalties, surcharges and income taxes.
(3) NPV and IRR are calculated to the start of construction activities for the Midwest project and excludes $16.8 million in
pre-FID expenditures.
(4) Payback period is stated as number of months to payback from the start of uranium production.
Mineral Resource Estimate
The Midwest uranium project is comprised of two primary deposits: Midwest Main and Midwest A. The
Midwest Main mineral resource estimate has been updated to reflect additional drill holes completed since
the previous mineral resource estimate from 2018. The additional drilling consisted primarily of test well
installations for ISR de-risking activities and certain targeted resource definition drill holes.
As a result of the additional drilling, the updated estimate of mineral resources consists of 38.7 million
pounds U3O8 in Indicated mineral resources (510,000 tonnes @ 3.5% U3O8), and 12.6 million pounds U3O8
in Inferred mineral resources (905,000 tonnes @ 0.64% U3O8).
The updated mineral resources estimated for Midwest, including the Midwest Main and Midwest A deposits,
are summarized below.
Table 3 – Estimated Midwest Mineral Resources (100% Basis)1,2,3,4,5
Deposit Category Zone6 Tonnage
(kt)
Grade7,8
(% U)
Metal
(tonnes U)
Metal
(Mlbs U3O8)
Denison’s
Share
(Mlbs U3O8)
Midwest
Main
Indicated UC 510 2.92 14,900 38.7 9.7
Inferred
UC 389 0.80 3,100 8.1 2.0
PER 449 0.36 1,600 4.1 1.0
BSMT 67 0.30 200 0.4 0.1
Midwest A
Indicated LG 566 0.74 4,200 10.8 2.7
Inferred LG 43 0.23 100 0.4 0.1
HG 10 24.00 2,400 6.4 1.6
Total Indicated 1,076 1.78 19,100 49.5 12.5
Total Inferred 958 0.77 7,400 19.4 4.9
(1) The effective date of the mineral resource estimate is December 2, 2024. The Qualified Person (QP) for the estimate is Mr. Matt
Batty, P.Eng., of Understood Mineral Resources.
(2) Mineral resource estimates are prepared in accordance with CIM Definition Standards (CIM, 2014) and the CIM Estimation of
Mineral Resources and Mineral Reserves Best Practice Guidelines (CIM, 2019). Mineral resources that are not mineral reserves
do not have demonstrated economic viability.
(3) Mineral resources are reported at a cut-off grade of 0.1% U3O8.
(4) Mineral resources are reported using a uranium price of USD$80/lb U3O8.
(5) All figures have been rounded to reflect the relative accuracy of the estimate. Figures may not add due to rounding.
(6) The Midwest Main and Midwest A deposits consist of various geological zones including the unconformity zone “UC”, perched zone
“PER”, basement zone “BSMT”, low-grade “LG”, and high-grade zone “HG”.
(7) Total Indicated and Total Inferred grades indicate average grades.
(8) % U3O8 equal to % U X 1.18.
Mining Overview & Potentially Mineable Resources
The PEA is based on utilization of the ISR method for mining the unconformity-hosted portions of the
Midwest Main deposit. A three-phase development sequence is planned to exploit the orebody over an
approximately 6-year mine life in a manner that is projected to optimize NPV, IRR, and capital efficiency,
while maintaining a steady rate of production throughout the projected mine life.
Key features of the application of ISR at the Midwest Main deposit include:
• Utilization of a low pH mining solution.
• Injection and extraction wells on a 10-metre spacing in a 5-spot pattern with extraction/recovery
wells placed in the centre of a ring of injection wells.
• A total of 676 ISR wells are required for complete coverage of the deposit.
• Utilization of commercial permeability enhancement techniques to increase hydraulic conductivity
of the near well environment within the deposit, where necessary.
• Use of a freeze wall (curtain) as a tertiary measure to isolate the mining area from the regional
groundwater, requiring the installation of 341 freeze holes.
• A total of 50 monitoring wells are projected to be required around the perimeter of the mineralized
zone and within the overlying and underlying aquifers, as dictated by geologic and hydrogeologic
parameters, and are spaced approximately every 125 metres.
An illustration of the planned mine is provided in Figure 2, which depicts the location of the ISR wellfield,
the three mining phases planned, and the associated surface infrastructure expected for the Midwest site.
In general, each extraction well is surrounded by 4 or more injection wells, the type of which has been
selected and/or located to optimize cost and recovery.
A unique characteristic of the planned Midwest Main ISR mine is the use of artificial ground freezing around
the perimeter of the planned mining phases to create a vertical hydraulic barrier surrounding the ISR mining
area. The freeze perimeter is a tertiary containment measure and is planned to consist of vertical wells
constructed from surface and extending into the impermeable basement rock underlying the deposit.
Mining is planned to occur over an approximate 6-year period, with a partial year of production occurring in
the final calendar year of the production plan. Production is expected to achieve nearly 6.1 million pounds
U3O8 annually for total recovered uranium of 37.4 million pounds U3O8 over the life of the project, which is
based on an estimated average mining recovery of 81%. Progressive reclamation and decommissioning
are planned to commence in each phase of the ore zone once production has ceased.
Midwest Main – Indicative Mine Production per Year (lbs U3O8)
Processing Overview
Processing of uranium-bearing solution (“UBS”) recovered from mine production at Midwest Main is
assumed to occur at the McClean Lake mill. The mill is part of the McClean Lake Joint Venture (“MLJV”),
which is owned by Orano Canada (77.5%) and Denison (22.5%) and is currently processing material from
the Cigar Lake mine (up to 18 million lbs U3O8/yr) under a toll milling agreement. Importantly, the mill is
licensed to process up to 24 million lbs U3O8 per year, and thus is expected to have approximately 6 million
lbs U3O8 per year in excess licenced processing capacity.
UBS from Midwest Main would be trucked to the McClean mill and offloaded into a storage tank providing
surge capacity for both the mine and mill. From the UBS storage tank it would be pumped into the
clarification circuit for fines removal prior to solvent extraction. Following clarification, the solution would be
-
1,000,000
2,000,000
3,000,000
4,000,000
5,000,000
6,000,000
7,000,000
1 2 3 4 5 6 7
Pounds U3O8 per year
Calendar Year
processed as per the current mill flowsheet, with final drummed “yellowcake” expected to be a blend of the
Midwest Main and Cigar Lake feed streams.
Mining of the Midwest Main deposit via ISR is expected to reduce tailings deposited to the McClean Lake
tailings management facility and reduce contaminant loading to the tailings circuit compared to conventional
mining and milling.
Site Infrastructure
As processing is assumed to occur at the McClean Lake mill, t he Midwest Main mine site is compact and
has been designed to limit environmental disturbance. The natural terrain of the area is used where
advantageous, further reducing the impact of the Project on the environment. As the Midwest Main deposit
is situated below the South McMahon Lake, a berm is planned to be constructed to extend the western
edge of the lake to provide a base for the installation of the ISR wellfield.
Based on the Midwest Main site layout (see Figure 2), the primary site facilities will consist of the ISR
wellfield and berm , freeze plant, storage pads and ponds , power substation and distribution, process
infrastructure, and operations facilities. The total area for these facilities is estimated to be less than one
square kilometer.
Additional on-site infrastructure includes a 6.5 km gravel road from Highway 905 to the site, a high-voltage
electrical power line from the existing SaskPower transmission line located alongside Highway 905, and
the existing dam across the Mink Arm of South McMahon Lake. Due to the relatively short expected
duration of mining activities and the mine site’s proximity to existing lodging facilities, no camp or airstrip is
envisioned to be required on site and existing facilities at Points North Landing, which is located
approximately 3 km from the Midwest property, are expected to be utilized.
Capital Costs
Initial capital costs are expected to be incurred during an approximately 24-month construction period that
will include the establishment of site infrastructure, as well as the freeze wall perimeter around the Phase
1 mining zone and initial ISR wellfield development within Phase 1. Sustaining capital costs are largely
related to the continuation of wellfield development for the second and third mining phase as well as the
completion of remediation and decommissioning of the mine site.
Table 4 – Midwest Capital Costs(1) ($ millions)
Description Initial Sustaining Total
ISR Wellfield 95.6 239.3 334.9
Milling (McClean Mill Modifications) 2.9 2.9
McClean Lake Mill Sustaining Capital 37.4 37.4
Surface Facilities 1.6 1.6
Utilities 0.9 0.9
Electrical 11.2 11.2
Civil & Earthworks 46.3 39.7 86.0
Road Upgrades (Midwest to McClean Lake) 1.2 1.2
SaskPower Line to Midwest 2.9 2.9
Surface Mobile Equipment 1.8 1.8
Remediation 86.8 86.8
Demolition 21.6 21.6
Contractor Direct Field Support Costs 12.3 5.4 17.7
Subtotal Direct Costs 176.7 430.2 606.9
Project Indirect Costs 18.8 6.7 25.5
Subtotal Direct + Indirect Costs 195.5 436.9 632.4
Contingency 58.7 10.1 68.8
Total Capital Cost 254.2 446.9 701.2
(1) Totals may not sum precisely due to rounding
In addition to the total capital costs identified in Table 4, further costs are expected to be incurred prior to
making a final investment decision (“FID”) . These costs are estimated to total $16.8 million and include
project evaluation and development prior to the start of construction. Taken together with estimated indirect
costs, owners’ costs, sustaining and decommissioning capital costs, contingencies, and excluding $16.8
million in costs related to the pre-FID period, total life of mine capital costs are estimated at CAD$701.2
million.
Operating Costs
Average estimated operating costs are estimated to be $15.78 (USD$11.69) per pound U3O8, which are
highly competitive and would position the Midwest Main ISR project amongst the lowest -cost uranium
mining operations globally.
Average operating costs estimated for life of mine are summarized in Table 5 below. A recovery rate of
98.5% has been assumed for processing of the UBS from Midwest Main at the McClean Lake mill.
Table 5 – Midwest Operating Cost per Pound U3O8 Produced(1)
CAD$ USD$
OPEX - Mining 2.89 2.14
OPEX - Milling, Transport, Weigh, Assay (Converter) 12.21 9.04
OPEX - G&A Site Support 0.11 0.08
OPEX - G&A Administration and Other 0.57 0.43
Total Operating Costs 15.78 11.69
(1) Totals may not sum precisely due to rounding
Uranium Selling Price Assumptions
The Base Case uranium price of USD$80.00 per pound U3O8 is assumed for all years of production and is
derived from the current long- term price of uranium as quoted by UxC , LLC in constant / uninflated 2024
dollars, translated to Canadian dollars using an exchange rate of 1.35 CAD/USD.
Economic Analysis
The Midwest PEA considers pre-tax and post-tax scenarios for the project’s base-case economic analysis
on a 100% basis.
Table 6 - Midwest Economic Analysis
Economic Metric 100% Project
Pre-Tax
100% Project
After-Tax
IRR % 111.1% 82.7%
Payback Years 0.5 0.7
NPV0.0% CAD$ '000 2,412,643 1,451,787
NPV8.0% CAD$ '000 1,618,411 964,661
Average U3O8
Price USD$/lb 80.00
Average FX Rate CAD$/US$ 1.35
Sensitivity analysis of the economic results shows that project economic s remain robust even in cases
where capital costs or operating costs increase by 30%, each of which are estimated to reduce the after-
tax base-case NPV8% by approximately 10%. The project also remains robust in the case of a decline in
uranium prices and offers excellent leverage to rising uranium prices. In the low -price scenario, a fixed
uranium selling price of US$65.00 per pound U3O8 is assumed and the project’s after-tax NPV8% decreases
to $675 million with an IRR of 66.5%. In the high-price scenario, a fixed uranium selling price of US$95.00
per pound U 3O8 is assumed and the project’s after -tax NPV 8% increases to $1.26 billion with an IRR
of 97.1%.
Recommendations
Given the favourable technical and economic results from the PEA, the independent authors of the study
recommend further advancement of the evaluation and de -risking of the application of the ISR mining
method to the Midwest Main deposit , including the potential completion of a Pre- Feasibility Study.
Additional work is recommended to focus on further classification of permeability characteristics of the ore
body, a detailed review of infrastructure designs, verification of costing elements, and completion of various
trade-off studies to assess opportunities for optimization identified during the PEA process.
SABRE Mining Method
In parallel to the continued evaluation of the potential use of the ISR mining method at Midwest, the MWJV
is also advancing the assessment of the use of the Surface Access Borehole Resource Extraction
(“SABRE”) mining method for extraction of the Midwest Main deposit. SABRE is a proprietary mining
method owned by the MLJV and currently being used at the McClean North deposit. While the PEA shows
significant potential for the use of the ISR mining method at Midwest Main, there can be no assurance that
the MWJV will ultimately advance the development of the Midwest Main deposit or that future development
of the deposit will occur using the ISR mining method. The SABRE mining method has been commercially
demonstrated and may also provide a viable means to extract the Midwest Main deposit.
About Denison
Denison is a uranium mining, exploration and development company with interests focused in the
Athabasca Basin region of northern Saskatchewan, Canada. The Company has an effective 95% interest
in its flagship Wheeler River Uranium Project, which is the largest undeveloped uranium project in the
infrastructure rich eastern portion of the Athabasca Basin region of northern Saskatchewan. In mid- 2023,
a feasibility study was completed for the Phoenix deposit as an ISR mining operation, and an update to the
previously prepared 2018 Pre-Feasibility Study was completed for Wheeler River's Gryphon deposit as a
conventional underground mining operation. 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 and are nearing completion
with approval of the project ’s Environmental Assessment ( “EA”) received from the Province of
Saskatchewan and Canadian Nuclear Safety Commission hearing dates set in the fall of 2025 for Federal
approval of the EA and project construction license.
Denison's interests in Saskatchewan also include a 22.5% ownership interest in the MLJV, which includes
unmined uranium deposits (planned for extraction via the MLJV’s SABRE mining method starting in 2025)
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 MWJV’s 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 ~384,000 hectares in the Athabasca Basin region.
Additionally, through its 50% ownership of JCU (Canada) Exploration Company, Limited (“JCU”), Denison
holds additional interests in various uranium project joint ventures in Canada, including the Millennium
project (JCU, 30.099%), the Kiggavik project (JCU, 33.8118%), 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 X (formerly Twitter) @DenisonMinesCo
Qualified Persons
The disclosure of scientific or technical information contained in this release has been reviewed and
approved by Mr. Chad Sorba, P.Geo., Denison’s Vice President, Technical Services & Project Evaluation,
who is a Qualified Person in accordance with the requirements of NI 43-101.
Technical Information
The M idwest PEA has been completed in accordance with NI 43- 101, Canadian Institute of Mining,
Metallurgy and Petroleum (CIM) standards, and best practices, as well as other standards such as the
AACE Cost Estimation Standards. Other than the risks identified in Denison’ s Annual Information Form
dated March 28, 2025 (the “AIF”), there are no known legal, political, environmental or other risks that could
materially affect the potential development of the mineral resources.
A technical report prepared in accordance with NI 43-101, with further details of the results of the Midwest
PEA, is anticipated to be completed and filed under Denison’s profile on Denison’s profile on SEDAR + at
www.sedarplus.ca and on EDGAR at www.sec.gov, a copy of which will also be available on Denison’s
website.
Data verification has been undertaken by Qualified Persons to support mineral resource and mineral
reserve estimation, including site visits, review of drill core, review of quality assurance program and quality
control measures and data, re- sampling and s ample analysis programs, and database verification.
Validation checks were performed on all data. For a further description of the data verification, assay
procedures and the quality assurance program and quality control measures applied by Denison, please
see Denison’s AIF filed under the Company’s profile on SEDAR+ and EDGAR.
Non-GAAP Financial Measures
This news release includes certain terms or performance measures commonly used in the mining industry
that are not defined under International Financial Reporting Standards ( “IFRS”). Such non -GAAP
performance measures, including operating costs and sustaining costs, are included because it
understands that investors use this information to determine the Company ’s ability to generate earnings
and cash flows. The Company believes that conventional measures of performance prepared in accordance
with IFRS do not fully illustrate the ability of mines to generate cash flows. Non-GAAP financial measures
should not be considered in isolation as a substitute for measures of performance prepared in accordance
with IFRS and are not necessarily indicative of operating costs, operating profit or cash flows presented
under IFRS.