First Mining Files Technical Report for the Positive Preliminary Economic Assessment for the Duparquet Gold Project, Quebec, Canada

Press Release

October 23, 2023 – Vancouver, Canada – First Mining Gold Corp. (“First Mining” or the “Company”) (TSX: FF) (OTCQX: FFMGF) (FRANKFURT: FMG) is pleased to announce that the Company has filed on SEDAR+ an independent Preliminary Economic Assessment (“PEA”) technical report (the “Report”) for its 100%-owned Duparquet Gold Project (“Duparquet” or the “Project”) located in the Abitibi region of Quebec, Canada.

The Report, entitled “NI 43-101 Technical Report: Preliminary Economic Assessment on the Duparquet Gold Project, Quebec, Canada” was prepared by G Mining Services Inc. of Montreal, Quebec (“G Mining”) in accordance with National Instrument 43-101 Standards of Disclosure for Mineral Projects (“NI 43-101”) and has an effective date of September 15, 2023.

The PEA results support a 15,000 tonnes per day open pit and underground mining operation over an 11-year mine life.  Highlights include:

• C$1.07 billion pre-tax NPV_5% and C$588 million after-tax NPV_5% at US$1,800/oz gold (“Au”)
• 24.9% pre-tax IRR; 18.0% after-tax IRR at US$1,800/oz Au
• Annual Life-of-Mine (“LOM”) recovered gold production of 233 koz
• Total LOM recovered gold of 2.5 Moz over an 11-year mine life
• Pre-tax payback of 3.8 years; after-tax payback of 4.8 years
• Initial capital costs estimated at C$706 million; sustaining and underground development capital costs estimated at C$738 million
• Average annual LOM Total Cash Cost of US$751/oz⁽¹⁾; average annual LOM All-In Sustaining Costs (“AISC”) of US$976/oz⁽²⁾

Note: Base case parameters assume a gold price of US$1,800/oz and an exchange rate (C$ to US$) of 1.33. All currencies are reported in Canadian dollars unless otherwise specified. NPV calculated as of the commencement of construction and excludes all pre-construction costs.

(1) Total Cash Costs consist of mining costs, processing costs, mine-level G&A, treatment and refining charges and royalties.
(2) AISC includes total cash costs plus sustaining capital, development capital and closure costs.

PEA Overview

The Duparquet Gold Project, located in the Abitibi region of Quebec, Canada, is one of the largest undeveloped gold projects in North America. The Project is located immediately north of the town of Duparquet which is approximately 50 kilometres northwest of Rouyn-Noranda, Quebec, a major mining service centre and home to the only remaining copper smelter in Canada. Duparquet currently hosts 3.4 million ounces of gold in the Indicated Mineral Resource category and 2.6 million ounces of gold in the Inferred Mineral Resource category, as set out in Table 4 in the Mineral Resource Estimate section.

The PEA evaluates recovery of gold from a 15,000 tonne-per-day (“tpd”) open pit and underground mining operation, with a process plant that includes crushing, grinding, and flotation, producing a concentrate for sale.  The PEA only considers the Duparquet gold deposit located on the Beattie, Donchester, Central Duparquet and Dumico claim blocks and does not include the Pitt Gold and Duquesne deposits (see Mineral Resource Estimate section).

Table 1: Key PEA Assumptions and Project Economics ⁽¹⁾

1. The reader is advised that the PEA is preliminary in nature and is intended to provide only an initial, high-level review of the Project potential and design options. The PEA mine plan and economic model include numerous assumptions and the use of Inferred mineral resources. Inferred mineral resources are considered too speculative geologically to have the economic considerations applied to them that would enable them to be categorized as mineral reserves and to be used in an economic analysis except as allowed for in PEA studies. There is no guarantee that Inferred resources can be converted to Indicated or Measured resources, and as such, there is no certainty that the PEA or Project economics described herein will be realized or achieved.
2. Total Cash costs consist of mining costs, processing costs, mine-level G&A, treatment and refining charges and royalties.
3. AISC includes total cash costs plus sustaining capital, development capital and closure costs.

Mineral Resource Estimate

In September 2022, the Duparquet Gold Project Mineral Resource Estimate (“MRE”) was updated by InnovExplo Inc. in accordance with NI 43-101. (See news release of September 12, 2022 for more details) The Duparquet Gold Project contains 3.44 million ounces of gold in the Measured & Indicated category, grading 1.55 g/t Au, and an additional 1.64 million ounces of gold in the Inferred category, grading 1.36 g/t Au (see Table 2).

In September 2023, new updated Mineral Resource Estimates were completed on First Mining’s 100% owned Pitt Gold and Duquesne projects and have added 1.0 million ounces of gold grading 2.32 g/t Au in the Inferred category (see Table 3), which will now form part of the larger consolidated Duparquet Gold Project.  During the final validation and completion of the Report, minor adjustments were made to the Pitt Gold deposit MRE statement disclosed in the September 7, 2023 press release.  The adjustments are presented in table 3 and 4 of this release for the Pitt Gold deposit and the consolidated 2023 MRE, respectively.

Following the updated Mineral Resource Estimate at Pitt Gold and Duquesne, the consolidated Duparquet Project now contains 3.44 million ounces of gold in the Measured & Indicated category, grading 1.55 g/t Au, and an additional 2.64 million ounces of gold in the Inferred category, grading 1.62 g/t Au.

Table 2: Duparquet Deposit Mineral Resource Estimate (Effective September 12, 2022)

Table 3: Pitt Gold (Adjusted) and Duquesne Deposits Mineral Resource Estimate (Effective September 15, 2023) (not included in the PEA)

Table 4: Duparquet Gold Project Consolidated Mineral Resource Estimate (Effective August 31, 2023)*

*Refer to respective deposit resource estimate table for cut-off grade; adjusted for Pitt Gold

Notes to accompany the Duparquet Gold Project Mineral Resource Estimates:

1. The independent qualified persons for the Duparquet mineral resource estimate, as defined by NI 43-101, are Marina Iund, P.Geo., Carl Pelletier, P.Geo. and Simon Boudreau, P.Eng. from InnovExplo. The effective date of the estimate is September 12, 2022.
2. The independent qualified persons for the Pitt Gold and Duquesne mineral resource estimates, as defined by NI 43 101, are Olivier Vadnais-Leblanc, P.Geo., Carl Pelletier, P.Geo., and Simon Boudreau, P.Eng. from InnovExplo. The effective date of the estimate is September 15, 2023.
3. These mineral resources are not mineral reserves, as they do not have demonstrated economic viability. There is currently insufficient data to define these Inferred mineral resources as Indicated or Measured mineral resources and it is uncertain if further exploration will result in upgrading them to an Indicated or Measured mineral resource category.  The mineral resource estimate follows current CIM Definition Standards.
4. The results are presented in situ and undiluted and have reasonable prospects of eventual economical extraction.
5. In-pit and Underground estimates encompass sixty (60) mineralized domains and one dilution envelop using the grade of the adjacent material when assayed or a value of zero when not assayed; The tailings estimate encompass four (4) zones.
6. Duparquet: In-pit and Underground: High-grade capping of 25 g/t Au; Tailings: High-grade capping of 13.0 g/t Au for Zone 1, 3.5 g/t Au for Zone 2, 1.7 g/t Au for Zone 3 and 2.2 g/t Au for Zone 4. High-grade capping supported by statistical analysis was done on raw assay data before compositing.
7. Pitt Gold: Underground: High-grade capping of 20 g/t Au. High-grade capping supported by statistical analysis was done on composited assays.
8. Duquesne: In-pit and Underground: High-grade capping of 55 g/t Au. High-grade capping supported by statistical analysis was done on composited assays.
9. In-pit and Underground: For Duparquet, the estimate used a sub-block model in GEOVIA SURPAC 2021 with a unit block size of 5m x 5m x 5m and a minimum block size of 1.25m x 1.25m x1.25m.  For Pitt Gold and Duquesne, the estimates used a sub-block model in GEOVIA SURPAC 2023 with a unit block size of 6m x 6m x 6m and a minimum block size of 1.5m x 0.5m x0.5m.  Grade interpolations were obtained by ID2 using hard boundaries. Duparquet Tailings: The estimate used a block model in GEOVIA GEMS with a block size of 5m x 5m x 1m. Grade interpolation was obtained by ID2 using hard boundaries.
10. In-pit and Underground: For Duparquet, a density value of 2.73 g/cm3 was used for the mineralized domains and the envelope. For Pitt Gold and Duquesne, a density value of 2.7 g/cm3 was used for the mineralized domains and the envelope.  A density value of 2.00 g/cm3 was used for the overburden. A density value of 1.00 g/cm3 was used for the excavation solids (drifts and stopes) assumed to be filled with water. Tailings: A fixed density of 1.45 g/cm3 was used in zones and waste.
11. In-pit and Underground: For Duparquet, the mineral resource estimate is classified as Measured, Indicated and Inferred. The measured category is defined by blocks having a volume of at least 25% within an envelope built at a distance of 10 m around existing channel samples. The Indicated category is defined by blocks meeting at least one (1) of the following conditions: Blocks falling within a 15-m buffer surrounding existing stopes and/or blocks for which the average distance to composites is less than 45 m. A clipping polygon was generated to constrain Indicated resources for each of the sixty (60) mineralized domains. Only the blocks for which reasonable geological and grade continuity have been demonstrated were selected. All remaining interpolated blocks were classified as Inferred resources. Blocks interpolated in the envelope were all classified as Inferred resources. Tailings: The Measured and Indicated categories were defined based on the drill hole spacing (Measured: Zones 1 and 2 = 30m x 30m grid; Indicated: Zone 3 = 100m x 100m grid and Zone 4 = 200m x 200m grid).  For Pitt Gold and Duquesne, the mineral resource estimate are completely classified as Inferred due to a lack of confidence in certain drill hole collar and underground development locations.
12. The Mineral Resource Estimate for Duquesne and Pitt Gold was prepared using 3D block modelling and the inverse distance squared (“ID2”) interpolation method.
13. The mineral resources are categorized as Inferred based on drill spacing, as well as geological and grade continuity. A maximum distance to the closest composite of 75 m for Inferred in all zones for Duquesne of 210 m for Inferred in all zones for Pitt Gold.
14. The reasonable prospect for an eventual economical extraction is met by having used reasonable cut-off grades both for a potential open pit and underground extraction scenarios (minimum mining width of 2m) and constraining volumes (Deswik optimized shapes and Whittle optimized pit-shells).
15. In-pit and Underground: The mineral resource estimate is locally pit-constrained with a bedrock slope angle of 50° and an overburden slope angle of 30°. The out-pit mineral resource met the reasonable prospect for eventual economic extraction by having constraining volumes applied to any blocks (potential underground extraction scenario) using DSO. Duparquet resources is reported at a rounded cut-off grade of 0.4 g/t Au (in-pit and tailings) and 1.5 g/t Au (UG). The cut-off grades were calculated using the following parameters: mining cost = CA$70.00 (UG); processing cost = CA$11.9 (tailing) to CA$17.0 (pit& UG); G&A = CA$8.75; refining and selling costs = CA$ 5.00; gold price = US$ 1,650/oz; USD:CAD exchange rate = 1.31; and mill recovery = 93.9%. The cut-off grades should be re-evaluated in light of future prevailing market conditions (metal prices, exchange rates, mining costs etc.).  Duquesne resources are reported at a rounded cut-off grade of 0.5 g/t Au (in-pit) and Pitt Gold and Duquesne resources are reported at a rounded cut-off grade of 1.75 g/t Au (UG). The cut-off grades were calculated using the following parameters: mining cost = CA$84.86 (UG); processing cost = CA$21.010; G&A = CA$11.75; refining and selling costs = CA$ 5.00; gold price = US$ 1,800/oz; USD:CAD exchange rate = 1.3; and mill recovery = 90%. The cut-off grades should be re-evaluated in light of future prevailing market conditions (metal prices, exchange rates, mining costs etc.).
16. The number of metric tons was rounded to the nearest thousand and ounces were rounded to the nearest hundred, following the recommendations in NI 43 101. Any discrepancies in the totals are due to rounding effects.
17. The qualified persons are not aware of any known environmental, permitting, legal, title-related, taxation, socio-political, or marketing issues, or any other relevant issue not reported herein, that could materially affect the Mineral Resource Estimate.

Environment & Community

The PEA has considered and incorporated the opportunity to leverage the Duparquet Gold Project development with the reclamation of the brownfield site conditions including the removal and reprocessing of over 4.1 Mt of uncontained historical mine tailings. With such measures incorporated into the PEA mine plan, in combination with the ability of the Project to collect and treat historically impacted groundwater via the excavation and dewatering of the open pit, the Project is positioned to deliver both environmental and socio-economic benefits via employment, contracting and revenue for the Municipality of Duparquet.  The PEA is anticipated to be refined and optimized based on consultation and input to be received by government, the Municipality of Duparquet and other local and regional stakeholders, and local First Nation community.

Since acquiring the Duparquet Gold Project in September of 2022, First Mining has prioritized meeting the people, communities and government representatives on project planning in an open and transparent manner. First Mining published the Mines d’Or Duparquet website to share project information and has recently finished renovations required to open a First Mining community relations office in Duparquet.   The Project provides an opportunity to address historical environmental aspects at the Project site to improve long-term sustainability, economic activity and support sustainable municipal planning and development.

The Municipality of Duparquet is in the Abitibi-Témiscamingue region which has been shaped primarily by natural resource-based industries, including mining, and forestry, where the mining industry accounts for 1 in 7 jobs in the region.

Qualified Persons

The affiliation and areas of responsibility for each of the Qualified Persons involved in preparing the PEA are as follows:

Table 5: Qualified Persons for PEA NI 43-101

The Company cautions that the results of the PEA are preliminary in nature and include Inferred Mineral Resources that are considered too speculative geologically to have the economic considerations applied to them that would enable them to be categorized as mineral reserves. There is no certainty that the results of the PEA will be realized.

Qualified Persons

Mr. Louis Martin P.Geo., (OGQ 0364), a consultant of First Mining, is a “Qualified Person” for the purposes of NI 43-101, and he has reviewed and approved the scientific and technical disclosure contained in this news release.

About First Mining Gold Corp.

First Mining is a gold developer advancing two of the largest gold projects in Canada, the Springpole Gold Project in northwestern Ontario, where we have commenced a Feasibility Study and permitting activities are on-going with a draft Environmental Impact Statement (“EIS”) for the project published in June 2022, and the Duparquet Project in Quebec, a PEA stage development project located on the Destor-Porcupine Fault Zone in the prolific Abitibi region.  First Mining also owns the Cameron Gold Project in Ontario and a portfolio of gold project interests including the Pickle Crow Gold Project (being advanced in partnership with Auteco Minerals Ltd.), the Hope Brook Gold Project (being advanced in partnership with Big Ridge Gold Corp.), and a large equity interest in Treasury Metals Inc.

First Mining was established in 2015 by Mr. Keith Neumeyer, founding President and CEO of First Majestic Silver Corp.

ON BEHALF OF FIRST MINING GOLD CORP.

Daniel W. Wilton
Chief Executive Officer and Director

For further information, please contact:

Toll Free: 1 844 306 8827 | Email: info@firstmininggold.com
Paul Morris | Director, Investor Relations | Email: paul@firstmininggold.com

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