Cosa Resources Corp press release

Denison Announces Results from Midwest ISR Preliminary Economic Assessment, Including After-Tax NPV of $965 Million

2025-08-06

TSXV - TSX Venture Exchange · Uranium · Copper · Helium · Hydrogen · Canada · Technical Studies

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TORONTO , Aug. 6, 2025 /CNW/ - Denison Mines Corp. ("Denison" or the "Company") (TSX: DML) (NYSE American: DNN) 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 3 O 8 over an approximately 6-year mine life, resulting in annual average production of nearly 6.1 million pounds U 3 O 8 , an after-tax base-case NPV of $965 million , and after-tax base-case IRR of 82.7%. PDF Version

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 NPV 8% of $243 million . Base case pre-tax NPV 8% 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 3 O 8 for total life of mine production of 37.4 million pounds U 3 O 8 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 NPV 8% 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 U 3 O 8 in Indicated mineral resources (510,000 tonnes @ 3.5% U 3 O 8 ), plus 12.6 million pounds U 3 O 8 in Inferred mineral resources (905,000 tonnes @ 0.64% U 3 O 8 ).

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 U 3 O 8 (650,000 tonnes at 2.60% U 3 O 8 ) | | Annual Production (Average) (2) | 6.1 million lbs U 3 O 8 | | Initial Capital Costs | $254 million | | Average Cash Operating Cost | $15.78 (USD$11.69) per lb U 3 O 8 | | All-in Cost (3) | $34.80 (USD$25.78) per lb U 3 O 8 |

| (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 U 3 O 8 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 U 3 O 8 to be produced. |

| Table 2 – Summary of Midwest Economic Analysis (100% Basis) | | | Uranium Selling Price | USD$ 80/lb U 3 O 8 (1) | | Exchange Rate (CAD$:USD$) | 1.35 | | Discount Rate | 8 % | | Operating profit margin (2) | 85.4 % | | Pre-tax NPV 8% (3) | $1.62 billion | | Pre-tax IRR (3) | 111.1 % | | Pre-tax payback period (4) | ~6 months | | Post-tax NPV 8% (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 U 3 O 8 in Indicated mineral resources (510,000 tonnes @ 3.5% U 3 O 8 ), and 12.6 million pounds U 3 O 8 in Inferred mineral resources (905,000 tonnes @ 0.64% U 3 O 8 ).

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 | Zone 6 | _Tonnage (kt) _ | Grade 7,8 (% U) | Metal

(tonnes U) | Metal

(Mlbs U 3 O 8 ) | _Denison's Share (Mlbs U 3 O 8 ) _ | | 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% U 3 O 8 . | | (4) | Mineral resources are reported using a uranium price of USD$80/lb U 3 O 8 . | | (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) | % U 3 O 8 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 U 3 O 8 annually for total recovered uranium of 37.4 million pounds U 3 O 8 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.

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 U 3 O 8 /yr) under a toll milling agreement. Importantly, the mill is licensed to process up to 24 million lbs U 3 O 8 per year, and thus is expected to have approximately 6 million lbs U 3 O 8 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 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, the 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 U 3 O 8 , 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 U 3 O 8 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 U 3 O 8 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 | | NPV 0.0% | CAD$ '000 | 2,412,643 | 1,451,787 | | NPV 8.0% | CAD$ '000 | 1,618,411 | 964,661 | | Average U 3 O 8 Price | USD$/lb | 80.00 | | | Average FX Rate | CAD$/US$ | 1.35 | |

Sensitivity analysis of the economic results shows that project economics 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 NPV 8% 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 U 3 O 8 is assumed and the project's after-tax NPV 8% 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 3 O 8 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.