First Mining Announces Positive Pre-Feasibility Study for the Springpole Gold Project, Ontario, Canada

2021-01-20

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_Pre-Tax NPV 5% of US$1.5 billion , Pre-Tax IRR of 36% After-Tax NPV 5% of US$995 million , After-Tax IRR of 29% Average Annual Gold Production of 335,000 ounces and AISC of US$577 /oz in Years 1 through 9 _

VANCOUVER, BC, Jan. 20, 2021 /CNW/ - First Mining Gold Corp. ("First Mining" or the "Company") (TSX: FF) (OTCQX: FFMGF) (FRANKFURT: FMG) is pleased to announce the positive results of a Pre-Feasibility Study ("PFS") completed for its 100%-owned Springpole Gold Project (the "Project" or "Springpole") located in northwestern Ontario, Canada . The PFS results support a 30,000 tonnes-per-day open pit mining operation over an 11.3 year mine life.

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PFS Highlights

US$1.5 billion pre-tax net present value at a 5% discount rate ("NPV 5% ") at US$1,600 /oz gold ("Au"), increasing to US$1.9 billion at US$1,800 /oz Au US$995 million after-tax NPV 5% at US$1,600 /oz Au, increasing to US$1.3 billion at US$1,800 /oz Au 36.4% pre-tax internal rate of return ("IRR"); 29.4% after-tax IRR at US$1,600 /oz Au Life of mine ("LOM") of 11.3 years, with primary mining and processing during the first 9 years and processing lower-grade stockpiles for the balance of the mine life After-tax payback of 2.4 years Declaration of Mineral Reserves: Proven and Probable Reserves of 3.8 Moz Au , 20.5 Moz silver ("Ag") (121.6 Mt at 0.97 g/t Au, 5.23 g/t Ag) Initial capital costs estimated at US$718 million , sustaining capital costs estimated at US$55 million , plus US$29 million in closure costs Average annual payable gold production of 335 koz (Years 1 to 9); 287 koz (LOM) Total cash costs of US$558 /oz (Years 1 to 9); and US$618 /oz (LOM) (1) All-in sustaining costs ("AISC") of US$577 /oz (Years 1 to 9), and AISC US$645 (LOM) (2)

| Note: Base case parameters assume a gold price of US$1,600/oz and a silver price of US$20, and an exchange rate (C$ to US$) of 0.75. All currencies are reported in U.S. 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 general and administrative ("G&A") costs, treatment and refining charges and royalties. | | (2) AISC consists of total cash costs plus sustaining and closure costs. |

"This PFS is an important milestone for the Company as we continue to advance and de-risk the Springpole Gold Project," stated Dan Wilton , CEO of First Mining. "First Mining is declaring mineral reserves for the first time ever on the Springpole Gold Project, reflecting the culmination of a year of detailed data collection, trade-off studies, and engineering and technical de-risking work done by First Mining and our partners on our project team. The results of the PFS confirm that Springpole has the potential to become a strategically significant, highly profitable gold mine in one of the most attractive mining jurisdictions in North America . The work we have undertaken to date to reduce the potential environmental impact from the project demonstrates the potential for Springpole to be developed in a responsible manner and to mitigate long-term impacts. We look forward to the Project's continual improvement through collaboration with our local and Indigenous communities of interest as we advance Springpole through the federal and provincial Environmental Assessment processes. We are very excited to have added Steve Lines and his team to lead this effort for First Mining. The team's recent and significant experience successfully permitting the Hardrock project in Ontario and other similar open pit mining projects in Canada requiring in-lake cofferdams and associated dewatering will serve us well as we continue to advance Springpole."

This PFS for the Springpole Gold Project was prepared by AGP Mining Consultants Inc. ("AGP") of Toronto, Canada , and a technical report summarizing the PFS will be filed by the Company on SEDAR within 45 days of this news release.

PFS Overview The Springpole Gold Project, located in northwestern Ontario, Canada , is one of the largest undeveloped open pit gold projects in North America . The Project is located approximately 110 kilometres northeast of Red Lake . Springpole currently hosts 4.6 million ounces ("Moz") of gold in the Indicated Mineral Resource category and 0.3 Moz of gold in the Inferred Mineral Resource category, as set out in the table below.

The PFS evaluates recovery of gold and silver from a 30,000 tonne-per-day ("tpd") open pit operation, with a process plant that will include crushing, grinding, and flotation, with fine grinding of the flotation concentrate and agitated leaching of both the flotation concentrate and the flotation tails followed by a carbon-in-pulp recovery process to produce doré bars.

Important parameters of the PFS are presented in the following table:

US$673/oz AuEq (co-product) | US$558/oz Au (net)

US$612/oz AuEq (co-product) | | All-In Sustaining Cost AISC (3) | US$645/oz Au (net)

US$698/oz AuEq (co-product) | US$577/oz Au (net)

| (1) All unit operating costs are shown on both equivalent as well as net of silver by-product credits | | (2) Cash costs consist of mining costs, processing costs, mine-level G&A, treatment and refining charges and royalties | | (3) AISC includes cash costs plus sustaining capital and closure costs |

Economic Sensitivities The Project economics and cash flows are highly sensitive to changes to the gold price.

Springpole Economic Sensitivity to Gold Price (base case in bold)

| Gold Price (US$/oz) | $1,400 | $1,600 | $1,800 | $2,000 | | Pre-Tax NPV 5% | US$1.04 billion | US$1.48 billion | US$1.92 billion | US$2.36 billion | | Pre-Tax IRR | 28.9% | 36.4% | 43.2% | 49.5% | | After-Tax NPV 5% | US$690 million | US$995 million | $1.30 billion | $1.60 billion | | After-Tax IRR | 23.3% | 29.4% | 35.0% | 40.1% |

Springpole Economic Sensitivity to Initial Capital Costs (base case in bold)

Springpole Economic Sensitivity to Operating Costs (base case in bold)

Mineral Processing and Metallurgical Testing The PFS reflects recoveries for both gold and silver that resulted from updated metallurgical test work completed in 2020. The test work focused on understanding the variability in gold and silver recoveries as well as optimizing the process flowsheet.

Based on the test work carried out, a flowsheet that includes flotation followed by leaching of reground concentrate and flotation tails presents as the most beneficial processing route for the Project. The processing plant also features a filtered tailings plant. This flowsheet is based on a primary grind size of P 80 150 micrometres ("µm") ahead of flotation, with a cleaner flotation concentrate being reground to approximately 17 µm ahead of agitated leaching. The overall recoveries expected and used for the economics presented in the PFS are 85.7% for gold and 89.5% for silver. The reduction in recoveries in the PFS stems primarily from a better understanding of the lower recoveries associated with processing lower grade ores. First Mining plans to undertake follow-up metallurgical test work to investigate additional opportunities to further increase recoveries and believes that this remains an important focus area for further improving the economics of the Project.

Mineral Resource and Mineral Reserve Estimates The mineral resource model prepared by SRK Consulting ( Canada ) Inc. ("SRK") is based on 662 core boreholes drilled by previous property owners during the period 2003 to 2013, and seven core holes drilled by First Mining in 2016 and 2020. The Mineral Resources at the Springpole Gold Project are shown below:

Mineral Resources inclusive of Mineral Reserves

| Category | Tonnes (Mt) | Grade

Au (g/t) | Grade

Ag (g/t) | Contained Metal

Au (Moz) | Contained Metal

Ag (Moz) | | Indicated | 151 | 0.94 | 5.0 | 4.6 | 24.3 | | Inferred | 16 | 0.54 | 2.8 | 0.3 | 1.4 |

Notes:

The Qualified Person for the Mineral Resource estimate is Dr Gilles Arseneau , Ph.D., P.Geo., an SRK employee. The Mineral Resource estimate has an effective date of July 30, 2020 . Mineral Resources are reported in accordance with the May 2014 edition of the Canadian Institute of Mining, Metallurgy and Petroleum (CIM) Definition Standards for Mineral Resources and Mineral Reserves. Mineral Resources are reported inclusive of the Mineral Resources that have been converted to Mineral Reserves. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability. All figures are rounded to reflect the relative accuracy of the estimate. All composites have been capped where appropriate. Mineral Resources potentially amenable to open pit mining are reported within an optimized constraining shell using the following parameters: Mineral Resources are reported at a cut-off grade of 0.3 g/t Au.

The Mineral Reserves for the Springpole Gold Project are based on the conversion of Indicated Mineral Resources within the current pit design. The Springpole Gold Project Mineral Reserves are shown below:

Springpole Proven and Probable Reserves

| Category | Tonnes (Mt) | Grade

Au (g/t) | Grade

Ag (g/t) | Contained Metal

Au (Moz) | Contained Metal

Ag (Moz) | | Proven | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | | Probable | 121.6 | 0.97 | 5.23 | 3.8 | 20.5 | | Total | 121.6 | 0.97 | 5.23 | 3.8 | 20.5 |

Notes:

The Mineral Reserve estimate has an effective date of December 30, 2020 and is based on the Mineral Resource estimate that has an effective date of July 30, 2020 . The Mineral Reserve estimate was completed under the supervision of Gordon Zurowski , P.Eng., of AGP, a Qualified Person as defined under NI 43-101. Mineral Reserves are stated within the final design pit based on a US$878 /oz Au pit shell with a US$1,350 /oz Au price for revenue. The equivalent cut-off grade was 0.34 g/t Au for all pit phases. The mining cost averaged CAD$1.94 /t mined, processing cost averaged CAD$14.50 /t milled, and the G&A cost averaged CAD$1.06 /t milled. The process recovery for gold averaged 88% and the silver recovery was 93%. The exchange rate assumption applied was C$1.30 equal to US$1.00 .

The mineral resources defined in the PFS do not reflect the significant opportunities that are available for resource expansion or discovery of additional ore bodies in the Springpole district. First Mining believes that Springpole has several avenues for resource expansion, both within the existing property footprint and regionally in the under-explored Birch Uchi Greenstone belt. In 2021, First Mining is planning to undertake a further 10,000 m of diamond drilling at the Springpole Gold Project for metallurgy, exploration, condemnation, and geotechnical purposes, and continues to review other exploration opportunities in the area.

Capital Costs The capital cost estimate for the proposed open pit operation in the PFS is based on the scheduled plant throughput rates, as well as a review of similar sized open pit gold operations.

The following table provides a summary of the capital cost estimate:

Capital Cost Estimate Details

| Mining | 144 | | Coffer Dams | 9 | | Bulk Earthworks | 12 | | Tailings Filtration | 82 | | Process Plant | 214 | | On-Site Infrastructure | 38 | | Off-Site Infrastructure | 35 | | Total Direct Costs | 536 | | Indirects | 48 | | EPCM | 38 | | Owner's Cost | 16 | | Provisions | 81 | | Initial Capital | 718 | | Sustaining Capital | 55 | | Closure Costs | 29 | | Total Capital | 803 |

| Note: EPCM = engineering, procurement and construction management. |

Mining Capital Costs The open pit mining activities for the Project were assumed to be undertaken by a leased fleet. Mining capital costs were estimated based on a detailed equipment schedule matched to the mining production schedule. Total initial mining capital was estimated at US$144 million , inclusive of capitalized stripping, Waste Management Facility ("WMF") construction and equipment.

Processing Capital Costs The process plant was designed using conventional processing unit operations. It will treat 30,000 tpd or 1,250 tonnes/hour based on an availability of 8,059 hours per annum or 92%. The crusher plant section design is set at 75% availability and the gold room availability is set at 52 weeks per year including two operating days and one smelting day per week. The plant will operate with two shifts per day, 365 days per year, and will produce doré bars.

Initial capital costs for the processing facility were estimated to be US$415 million , inclusive of a US$54 million contingency allocation. No major plant re-build or expansion was considered during the LOM, with sustaining capital set to maintain the equipment in operating condition. No allowance for salvage value was made.

Operating Costs

Overall operating costs for the LOM, and the unit costs, are summarized below:

| Mining | 793 | 6.52 | 246 | | Processing (1) | 1,323 | 10.87 | 410 | | On-Site G&A | 96 | 0.79 | 30 | | Total Operating Cost | 2,212 | 18.18 | 686 | | Treatment & Refining Charges | 10 | 0.09 | 3 | | Royalty | 74 | 0.61 | 23 | | Silver Credits | (302) | (2.48) | (94) | | Cash Costs | 1,994 | 16.40 | 618 | | Sustaining Capital (2) | 85 | 0.70 | 26 | | All-in Sustaining Costs (AISC) | 2,079 | 17.09 | 645 |

| (1) Includes processing, WMF operating costs and water management costs

(2) Includes closure capital |

Operating Cost Estimate Details

Mining Costs The PFS contemplates open pit mining undertaken by a leased fleet. An average unit mining cost of CAD$1.96 /t of material mined was used in the economics. The cost estimate was built from first principles with detailed haulage profiles, vendor quotations for equipment and consumables, and is based on experience of similar sized open pit operations and local conditions. The open pit mining costs consider variations in haulage profiles by month and by year and variable equipment requirements necessary to meet the plant production.

Processing Costs An average cost of US$10.87 /t of processed material was used in the PFS, based on the updated process flowsheet. This includes tailings handling, labour, consumables, maintenance, and supplies. A power cost of CAD$0.08 /kWh was assumed.

Production Schedule and Mine Plan Mining would occur as a series of phases within the ultimate pit with a maximum depth of approximately 350 metres. The deposit is planned to produce a total of 121.6 Mt of plant process feed and 287.5 Mt of waste (2.36:1 overall strip ratio) over an 11.3 year mine operating life. The current LOM plan focuses on achieving consistent processing feed production rates, mining of higher-grade material early in the schedule, and balancing grade and strip ratios.

Site Infrastructure

Springpole Lake Dewatering The deposit sits underneath a small portion of the northern bay of Springpole Lake. Two dewatering dikes (coffer dams), with a total length of approximately 940 metres, will need to be constructed to allow this small portion of the bay to be dewatered. The coffer dams will have a maximum height of 17 metres. The area proposed to be dammed and dewatered totals approximately 150 hectares and represents approximately 6% of the entire surface area of Springpole Lake (and approximately 3% of the volume).

Waste Management Facility The WMF was re-envisioned in the PFS as a comingled waste rock and filtered tailings facility to reduce the overall footprint and to spread the required costs over the LOM. The WMF will be located immediately west of the pit, and in the initial stages it will occupy a smaller footprint to reduce the construction period and to minimize the initial capital requirement. The surface of the filtered tailings and waste rock within the WMF will be graded to minimize infiltration and encourage water flow to defined sumps/pumping points. A synthetic liner has been included in the PFS design to limit exfiltration of contact water, and will be further considered through on-going environmental assessment work including additional geochemical testing and WMF design optimizations. The collected surface water will be directed to a Contact Water Management Pond ("CWMP") that will be located southeast of the WMF. The water stored in the CWMP will be used to supplement mineral processing and/or will be treated and released to Springpole Lake.

Access Roads The Company believes that the Project can play a meaningful role in encouraging the development of the road network in the area, with potential to connect the communities to the north with an all-season road that will provide access to the Municipality of Sioux Lookout , a major services hub for Northern Ontario . The PFS considers that the access road may be completed prior to commencement of construction and is not part of the study.

Power Infrastructure Approximately 55MW of electrical demand will be supplied via a new 230 kV overhead transmission line, built to connect to the provincial grid's 230 kV line approximately 75 km to the southeast.

Project Enhancement Opportunities The PFS identified several opportunities to enhance the economics of the Springpole Gold Project, and they will be investigated as First Mining continues to advance the Project. These opportunities include:

Existing Resource Upgrades. Inferred Mineral Resources are contained within the existing pit design, and with additional infill drilling, these resources may potentially support conversion of some or all of this material into Indicated Mineral Resources that could be converted to Probable Mineral Reserves and evaluated in a Feasibility Study ("FS"). Mine Plan Optimization. Refined pit optimization parameters could result in better optimized open pit limits which could reduce the overall strip ratio. Process Optimization. Continued efforts to investigate opportunities to improve the metal recoveries through further metallurgical testing and refining milling processes, as well as other process optimizations. Further Geotechnical Studies. A better hydrogeological and geotechnical understanding may increase pit slope angles, potentially reducing costs associated with mining waste material. Additional Mineralization. There are geophysical targets in the area around the current resource, where additional drilling has the potential to identify additional mineralization that could support Mineral Resource estimation with upside potential for the LOM.