Alamos Gold Announces Island Gold District Base Case Life of Mine Plan Outlining One of the Largest and Lowest-Cost Gold Mines in Canada with Significant Upside
F O R I M M E D I A T E R E L E A S E
ALAMOS GOLD INC.
Brookfield Place, 181 Bay Street, Suite 3910, P.O. Box #823 Toronto, Ontario, Canada M5J 2T3 Telephone: (416) 368-9932 or 1 (866) 788-8801
All amounts are in United States dollars, unless otherwise stated.
Alamos Gold Announces Island Gold District Base Case Life of Mine Plan Outlining One of the Largest and Lowest-Cost Gold Mines in Canada with Significant Upside
Toronto, Ontario (June 23, 2025) – Alamos Gold Inc. (TSX:AGI; NYSE:AGI) (“Alamos” or the “Company”) today reported results of the Base Case Life of Mine Plan (“Base Case LOM Plan”) completed on the Island Gold District operation, located in Ontario, Canada. The Base Case LOM Plan integrates Island Gold and Magino as one consolidated long-life operation that is expected to become one of the largest, lowest-cost, and most profitable gold mines in Canada. An Expansion Study is expected to be released in the fourth quarter of 2025 detailing the significant upside potential within the Island Gold District beyond the Base Case LOM Plan. The Base Case LOM Plan has been updated to reflect the current costing environment, significant growth in Mineral Reserves at Island Gold, operating savings resulting from the use of a larger and more efficient Magino mill, and scope changes since the Phase 3+ Expansion Study (“Phase 3+ Study”), which was completed in 2022. The Base Case LOM Plan includes Mineral Reserves only at Island Gold and Magino. Both deposits have significant Measured, Indicated and Inferred Mineral Resources, which have not been factored into the Base Case LOM Plan and economic analysis. All amounts are in United States dollars, unless otherwise stated.
“The Base Case Plan for the Island Gold District outlines an attractive, long-life operation that is expected to become one of Canada’s largest, lowest-cost, and most profitable gold mines. This is a first look at an operation with significant upside potential which we expect to detail in an Expansion Study later this year. We expect this to include a larger Mineral Reserve through ongoing Mineral Resource conversion, and a potential further expansion up to 20,000 tonnes per day, supporting an even larger, more valuable, and profitable operation. Longer-term, we see excellent opportunities for that value to continue to grow through ongoing exploration success at Island Gold, and a number of emerging higher-grade regional targets that have the potential to support multiple sources of ore within an expanded mill,” said John A. McCluskey, President and Chief Executive Officer.
Base Case LOM Plan Highlights:
Average annual gold production of 411,000 ounces starting in 2026 and over the initial 12 years, a 43% increase from the mid-point of 2025 production guidance driven by the completion of the Phase 3+ Expansion
- Average annual production of 306,000 ounces over the 20-year Mineral Reserve life
- Significant upside potential through a further expansion of the operation, and the expected conversion of a significant portion of the large Mineral Resource base to Mineral Reserves through ongoing delineation drilling
Low-cost structure: average mine-site all-in sustaining costs (“mine-site AISC”) of $915 per ounce over the initial 12 years (2026+), a 19% decrease from the mid-point of 2025 guidance
- Average total cash costs of $581 per ounce over the initial 12 years (average $699 per ounce over the life of mine)
- Average AISC of $1,003 per ounce over the life of mine, an 11% decrease from 2025 guidance
Long-life operation supported by a large and growing Mineral Reserve base
- 48% increase in total Mineral Reserves to 6.3 million ounces (88.6 million tonnes (“mt”) grading 2.23 grams per tonne (“g/t Au”), including:
- 4.1 million ounces grading 10.85 g/t Au (11.8 mt) at Island Gold underground, up 80% from the end of 2024 reflecting the conversion of Mineral Resources
- 2.2 million ounces grading 0.91 g/t Au (76.9 mt) at Magino open pit, up 12% from the end of 2024
Significant upside potential expected to be outlined in an Expansion Study in the fourth quarter of 2025
- Base Case LOM Plan based only on Mineral Reserves and long-term milling
rates of 12,400 tonnes per day (“tpd”)
- Expansion Study expected to include an increase in milling rates potentially to between 18,000 and 20,000 tpd supporting higher throughput rates from both Island Gold and Magino, and
- The incorporation of a larger Mineral Reserve through the expected
conversion of a significant portion of existing Mineral Resources, which consist of:
- Island Gold Underground
- M&I Mineral Resources: 1.0M oz grading 10.49 g/t Au (3.1 mt)
- Inferred Mineral Resources: 1.3M oz grading 16.88 g/t Au (2.4 mt)
- Magino Open Pit
- M&I Mineral Resources: 1.8M oz grading 0.91 g/t Au (60.3 mt)
- Inferred Mineral Resources: 1.2M oz grading 0.92 g/t Au (40.3 mt)
Low capital intensity
• Growth capital of $453 million with the majority to be spent over the next two years, focused on completing the Phase 3+ Expansion and Magino mill expansion to 12,400 tpd
- Sustaining capital of $1,808 million over the life of mine, or $304 per ounce
- Sustaining capital intensity expected to decrease within Expansion Study reflecting a larger Mineral Reserve leveraging existing infrastructure
- Total all-in cost of $1,079 per ounce, including total capital intensity of $380 per ounce
Attractive base case economics with significant upside
- After-tax net present value (“NPV”) (5%) of $4.5 billion, (base case long-term gold price assumption of $2,400 per ounce and USD/CAD foreign exchange rate of $0.75:1)
- After-tax NPV (5%) of $6.7 billion, at current gold prices of approximately
$3,300 per ounce
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- Expansion Study is expected to demonstrate attractive economics with a
further increase in value reflecting a larger Mineral Reserve and higher throughput rates
Phase 3+ Expansion expected to be completed during the second half of 2026
- Base Case LOM Plan is consistent with existing three-year production guidance
- The slight delay in the completion of the Phase 3+ Expansion (from the first half of 2026 previously) is not expected to impact production or cost guidance in 2026 and 2027
- Work on the Phase 3+ Expansion has been largely de-risked with a number of key projects substantially complete including the shaft surface infrastructure, and shaft development which is currently at 92% of its ultimate planned depth
Low and decreasing Greenhouse Gas (“GHG”) emission intensity
• 29% reduction of GHG emissions per ounce from already low levels which are currently 57% below the industry average. This is expected to be achieved through the completion of the Phase 3+ Expansion, and connection of the Magino mill to grid power in 2026
Fully funded growth: ongoing free cash flow with significant growth expected in 2026
- Island Gold District is expected to self finance all remaining growth capital at current gold prices with significant free cash flow growth following the completion of the Phase 3+ Expansion in 2026
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| Base Case LOM Plan Highlights | ||
| Production | ||
| Mine life (years) | 20 H2 2026 6,112 411 306 88,648 12,400 2.23 2,400 10.85 10,000 0.91 96.3% | |
| Phase 3+ Expansion completion date | ||
| Total gold production (000 ounces) | ||
| Average annual gold production – 12-year average, 2026+ (000 ounces) | ||
| Average annual gold production – life of mine (000 ounces) | ||
| Total mill feed (000 tonnes) | ||
| Average mill throughput – 2027+ (tpd) | ||
| Average gold grade (g/t Au) | ||
| Average Island Gold ore throughput – 2027+ (tpd) | ||
| Average Island Gold ore grade milled (g/t Au) | ||
| Average Magino ore throughput (tpd) | ||
| Average Magino ore grade milled (g/t Au) | ||
| Average recovery (%) | ||
| Operating Costs | ||
| Open pit mining cost (C$/tonne of total material mined) | $4.24 $124 $16.74 $13.73 $581 $699 $915 $1,003 | |
| Underground mining cost (C$/tonne of ore mined) | ||
| Processing cost (C$/tonne of ore milled) | ||
| G&A cost (C$/tonne of ore milled) | ||
| Total cash cost – 12-year average, 2026+ (per ounce sold)1,2 | ||
| Total cash cost – life of mine (per ounce sold)1,2 | ||
| Mine-site all-in sustaining cost – 12-year average, 2026+ (per ounce sold)1,2 | ||
| Mine-site all-in sustaining cost – life of mine (per ounce sold)1,2 | ||
| Capital Costs (millions) | ||
| Growth capital expenditure | $453 $1,808 $2,261 $380 $1,079 | |
| Sustaining capital expenditure5 | ||
| Total capital expenditure – life of mine | ||
| Total capital expenditure (per ounce sold) – life of mine2 | ||
| Total all-in cost (per ounce sold) – life of mine2,3 | ||
| Base Case Economic Analysis: $2,400 per ounce Gold Price | ||
| (USD/CAD foreign exchange rate of $0.75:1) 4 | ||
| NPV @ 0% discount rate (millions, after-tax) | $6,417 $4,477 | |
| NPV @ 5% discount rate (millions, after-tax) | ||
| Economic Analysis at $3,300 per ounce Gold Price | ||
| (USD/CAD foreign exchange rate of $0.75:1) | ||
| NPV @ 0% discount rate (millions, after-tax) | $9,682 $6,667 | |
| NPV @ 5% discount rate (millions, after-tax) |
1. Total cash costs and mine-site all-in sustaining costs include royalties and silver as a by-product credit
2. Please refer to the Cautionary Notes on non-GAAP Measures and Additional GAAP Measures
3. Total all-in cost per ounce sold is calculated as total cash cost per ounce plus total capital per ounce sold over the life of mine
4. The Base Case LOM Plan includes a gold price of $3,000/oz in 2025 through to 2027, and a long-term (2028+) gold price of $2,400/oz, as well as a USD/CAD foreign exchange rate of $0.73:1 in 2025, $0.74:1 in 2026 and 2027, and $0.75:1 from 2028 onwards
5. Sustaining capital includes reclamation and capital leases
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Prior Disclosure Regarding Island Gold Mine
As a result of a review by staff of the Ontario Securities Commission, the Company is providing the following corrective information regarding its disclosure with respect to the Island Gold Mine. The 2025 Base Case Island Gold District Technical Report is being prepared and will be disclosed without the inclusion of Inferred Mineral Resources in economic analyses, including production schedules, mine life and cash flow models. The 2025 Base Case Island Gold District Technical Report will supersede any prior technical reports published by Alamos with respect to the Island Gold Mine.
Prior public disclosure regarding the Island Gold Mine included the use of Inferred Mineral Resources in economic analyses, including production schedules, mine life and cash flow models. Such disclosure was prohibited under paragraph 2.3(1)(b) of National Instrument 43- 101 Standards of Disclosure for Mineral Projects (NI 43-101), which restricts public disclosure of the results of an economic analysis that includes or is based on Inferred Mineral Resources. In addition, NI 43-101 incorporates by reference the CIM Definition Standards (2014), which states that Inferred Mineral Resources must not be included in the economic analysis, production schedules, or estimated mine life in publicly disclosed prefeasibility or feasibility studies, or in the life of mine plans and cash flow models of developed mines. Inferred Mineral Resources are considered too speculative geologically to have economic considerations applied to them that would enable them to be categorized as Mineral Reserves and there can be no certainty that the results of an economic analysis including Inferred Mineral Resources would be realized.
Mineral Reserves and Resources
An updated Proven and Probable Mineral Reserve totaling 88.6 mt, grading 2.23 g/t Au, containing 6.3 million ounces of gold has been included in the Base Case LOM Plan. This represents a 48% increase from the 4.3 million ounces reported at the end of 2024, reflecting the conversion of Measured, Indicated and Inferred Mineral Resources at Island Gold and Magino. Only Mineral Reserves have been incorporated into the Base Case LOM plan and economic analysis.
Island Gold’s updated Mineral Reserve increased by 80% to 4.1 million ounces, driven by Mineral Resource conversion. An updated classification methodology has been adopted based on definition drilling, extensive historical and current production data, reconciliation, and underground mapping, which demonstrates that Indicated Mineral Resource continuity can be reliably established with an average drill spacing of 40 metres, versus 25 metres previously. This contributed to the conversion of a portion of the large Inferred Mineral Resource to Measured & Indicated Mineral Resources, which was subsequently converted to Mineral Reserves.
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Mineral Reserves – Effective as of December 31, 2024
| Proven and Probable Gold Mineral Reserves | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| June 2025 Update | February 2025 Update | % Change | |||||||||||
| Tonnes | Grade | Ounces | Tonnes | Grade | Ounces | Tonnes | Grade | Ounces | |||||
| (000’s) | (g/t Au) | (000’s) | (000’s) | (g/t Au) | (000’s) | (000’s) | (g/t Au) | (000’s) | |||||
| Island Gold | |||||||||||||
| Proven | 821 | 11.82 | 312 | 727 | 12.74 | 298 | 18% | -11% | 5% | ||||
| Probable | 10,947 | 10.78 | 3,795 | 5,505 | 11.23 | 1,987 | 112% | -10% | 91% | ||||
| Proven and Probable | 11,769 | 10.85 | 4,107 | 6,232 | 11.40 | 2,285 | 89% | -5% | 80% | ||||
| Magino | |||||||||||||
| Proven | 22,163 | 0.88 | 626 | 19,684 | 0.89 | 561 | 13% | -1% | 12% | ||||
| Probable | 54,710 | 0.92 | 1,613 | 48,715 | 0.92 | 1,447 | 12% | 0% | 11% | ||||
| Proven and Probable | 76,873 | 0.91 | 2,240 | 68,400 | 0.91 | 2,008 | 12% | 0% | 12% | ||||
| Island Gold District | |||||||||||||
| Proven | 22,984 1.27 938 | 20,411 1.31 859 | 13% -4% 9% | ||||||||||
| Probable | 65,657 2.56 5,408 | 54,220 1.97 3,434 | 22% 28% 57% | ||||||||||
| Proven and Probable | 88,642 2.23 6,347 | 74,632 1.79 4,293 | 19% 25% 48% |
- Mineral Reserves reported are consistent with the CIM Definition Standards for Mineral Resources and Mineral Reserves
- Mineral Reserves are reported to a cut-off grade of 3.78 Au g/t at Island Gold and 0.30 Au g/t for Magino
• The cut-off grades are based on a gold price of $1,600/oz Au at both Island Gold and Magino
- Silver is not used in the cut-off grade calculation
- Totals may not add up due to rounding
- Chris Bostwick, FAusIMM, Senior Vice President, Technical Services is the Qualified Person for Magino’s Mineral Reserve estimate. Mr. Bostwick is a Qualified Person within the meaning of Canadian Securities Administrator's National Instrument 43-101 ("NI 43-101")
- Nathan Bourgeault, P.Eng., Manager, Technical Services for the Island Gold District is the Qualified Person for Island Gold’s Mineral Reserve estimate. Mr. Bourgeault is a Qualified Person within the meaning of Canadian Securities Administrator's National Instrument 43-101 ("NI 43-101")
Mineral Resources for Island Gold and Magino, as detailed below, have not been included in the Base Case LOM Plan and represent potential upside. A significant portion of Mineral Resources at Island Gold, and Measured and Indicated Mineral Resources at Magino, are expected to be converted to Reserves and incorporated into the Expansion Study to be released in the fourth quarter of 2025. The decrease in Inferred Mineral Resources at Island Gold reflects the conversion to Measured and Indicated Mineral Resources and Mineral Reserves.
The Mineral Resource conversion rate to Reserves at Island Gold continues to average more than 90%. This high rate of conversion is expected to continue based on ongoing success with the delineation drilling program.
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Mineral Resources – Effective as of December 31, 2024
| Measured and Indicated Gold Mineral Resources (exclusive of Mineral Reserves) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| June 2025 Update | February 2025 Update | % Change | ||||||||||||
| Tonnes | Grade | Ounces | Tonnes | Grade | Ounces | Tonnes | Grade | Ounces | ||||||
| (000’s) | (g/t Au) | (000’s) | (000’s) | (g/t Au) | (000’s) | (000’s) | (g/t Au) | (000’s) | ||||||
| Island Gold | ||||||||||||||
| Measured | 470 | 14.66 | 222 | 235 | 10.96 | 83 | 100% | 34% | 167% | |||||
| Indicated | 2,640 | 9.75 | 827 | 1,898 | 8.49 | 518 | 39% | 15% | 60% | |||||
| Measured and Indicated | 3,110 | 10.49 | 1,049 | 2,113 | 8.76 | 601 | 47% | 20% | 75% | |||||
| Magino | ||||||||||||||
| Measured | 5,061 | 0.87 | 141 | 5,579 | 1.00 | 179 | -9% | -13% | -21% | |||||
| Indicated | 55,209 | 0.91 | 1,615 | 57,110 | 0.94 | 1,726 | -3% | -3% | -6% | |||||
| Measured and Indicated | 60,270 | 0.91 | 1,756 | 62,689 | 0.94 | 1,905 | -4% | -3% | -8% | |||||
| Island Gold District | ||||||||||||||
| Measured | 5,531 2.04 363 | 5,814 1.40 262 | -5% 46% 39% | |||||||||||
| Indicated | 57,849 1.31 2442 | 59,008 1.18 2,244 | -2% 11% 9% | |||||||||||
| Measured and indicated | 63,380 1.38 2,805 | 64,802 1.20 2,506 | -2% 14% 12% | |||||||||||
| Inferred Gold Mineral Resources (exclusive of Mineral Reserves) | ||||||||||||||
| Island Gold | 2,449 16.88 1,329 | 7,106 16.52 3,774 | -66% 2% -65% | |||||||||||
| Magino | 40,291 0.92 1,191 | 40,383 0.91 1,177 | 0% 1% 1% | |||||||||||
| Island Gold District | 42,740 1.83 2,520 | 47,489 3.24 4,951 | -10% -44% -49% | |||||||||||
| • Mineral Resources reported are consistent with the CIM Definition Standards for Mineral Resources and Mineral Reserves | ||||||||||||||
| • Mineral Resources are reported at an assumed gold price of $1,800/oz | ||||||||||||||
| • Mineral Resources are not Mineral Reserves and do not have demonstrated economic viability. There is no certainty that all | ||||||||||||||
| or any part of the Mineral Resources estimated will be converted into Mineral Reserves | ||||||||||||||
| • Island Gold underground Resources are estimated at a cut-off grade of 3.36 g/t | ||||||||||||||
| • Magino open pit Resources are estimated at a cut-off grade of 0.28 g/t Au | ||||||||||||||
| • Contained Au ounces are in-situ and do not include metallurgical recovery losses | ||||||||||||||
| • Mineral Resources are exclusive of Mineral Reserves | ||||||||||||||
| • Totals may not add up due to rounding | ||||||||||||||
| • Jeffrey Volk, CPG, FAusIMM, Director of Reserves and Resources for Alamos Gold Inc is the Qualified Person for the Magino | ||||||||||||||
| open pit Mineral Resource estimate. Tyler Poulin, P. Geo., Geology Superintendent for Alamos Gold , is the Qualified Person | ||||||||||||||
| for the Island Gold underground Mineral Resource estimate. Mr. Volk and Mr. Poulin are Qualified Persons within the meaning | ||||||||||||||
| of Canadian Securities Administrator's National Instrument 43-101 ("NI 43-101") |
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Economic Analysis
The Base Case LOM Plan has an estimated base case after-tax NPV (5%) of $4.5 billion assuming a long-term gold price of $2,400 per ounce and USD/CAD foreign exchange rate of $0.75:1.
Assuming a $3,300 per ounce gold price, the after-tax NPV (5%) increases to $6.7 billion. The mine plan, operating parameters and capital estimates incorporated in the Base Case LOM Plan are effective as the first quarter of 2025. The project economics are sensitive to metal price assumptions and input costs as detailed in the tables below.
Island Gold District: Base Case LOM Plan After-Tax NPV (5%) Sensitivity ($ Millions)
| -10% | -5% | Base Case | 5% | 10% | |||||
| Gold Price | $3,337 | $3,897 | $4,477 | $5,080 | $5,704 | ||||
| Canadian Dollar | $4,752 | $4,616 | $4,477 | $4,339 | $4,198 | ||||
| Capital Costs | $4,552 | $4,514 | $4,477 | $4,440 | $4,403 | ||||
| Operating Costs | $4,722 | $4,600 | $4,477 | $4,355 | $4,232 |
Island Gold District: Base Case LOM Plan After-Tax NPV (5%) Sensitivity to Gold Price
| Gold Price ($/oz) | After-Tax NPV5% ($M) | ||
|---|---|---|---|
| $2,000 | $2,942 | ||
| $2,400 (Base Case1) | $4,477 | ||
| $2,750 | $5,098 | ||
| $3,000 | $5,811 | ||
| $3,300 | $6,667 | ||
| $3,500 | $7,236 |
1. Base case includes a gold price of $3,000/oz in 2025 through to 2027, and a long-term (2028+) gold price of $2,400/oz
Base Case LOM Plan Overview
The Island Gold District is comprised of the Island Gold underground mine and the Magino open pit mine. Both operations will utilize the centralized Magino mill for processing ore and the Magino tailings management facility for tailings storage.
Underground ore from Island Gold is currently being processed through the Island Gold mill. During the third quarter of 2025, the Company expects to shut down the Island Gold mill and transition to processing both Island Gold and Magino ore through the Magino mill at a rate of approximately 11,200 tpd.
The Phase 3+ Expansion of Island Gold is expected to double underground mining rates to 2,400 tpd through the addition of a shaft and paste plant. Following completion of the expansion in 2026, underground mining will transition from trucking ore and waste to skipping ore and waste to surface, through the new shaft infrastructure. This is expected to drive production higher and costs significantly lower. The Magino mill will be expanded to 12,400 tpd to accommodate the increased production rates from Island Gold of 2,400 tpd, with the remaining 10,000 tpd coming from the Magino open pit.
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The Phase 3+ Expansion is expected to be completed during the second half of 2026, a slight delay from initial guidance of the first half of 2026 in the Phase 3+ Study, though this is not expected to impact current production and cost guidance for the Island Gold District in 2026 and 2027.
Base Case LOM Production and Mine-site AISC Profile
1. Please refer to Cautionary Notes on non-GAAP Measures and Additional GAAP Measures
2. For the purposes of calculating all-in sustaining costs at individual mine sites, the Company does not include corporate and administrative and corporate share-based compensation expenses
Phase 3+ Expansion Significantly De-Risked
The Phase 3+ Expansion of Island Gold underground has been significantly de-risked given the progress achieved to date, with details as follows:
- Shaft surface infrastructure is now substantially complete, including the headframe, hoist house and warehouse. The bin house has been erected and is currently being mechanically and electrically outfitted. The electrical infrastructure required for shaft development was completed in late 2023
- Shaft development is down to a depth of 1,265 metres, 92% of the ultimate planned depth of 1,379 metres
- Construction of the paste plant is 71% complete, and is expected to be fully completed by the end of 2025
- The 115kV powerline project is on track for completion by mid-2026. The power line will supply additional grid power sufficient to power the entire operation through lower cost power from the electric grid
- As a brownfield expansion of an existing operating mine, and with 76% of the growth capital spent or committed as of the end of May, the project is significantly de-risked. The shaft is expected to begin skipping ore from underground in the second half of 2026
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Mining
Island Gold underground Longitudinal long-hole open stoping will continue to be utilized as the primary mining method with the completion of the shaft and paste plant supporting the increase in mining rates to 2,400 tpd. Given the ongoing growth of the ore body, and as mining progresses deeper, a more geotechnically sound approach will be employed across the stope sequence with mining moving from the centre towards sill extremities (versus from the sill extremities towards the centre currently). The new approach will require increased underground development which will support an improved geotechnical mining sequence and a better managed stress environment, as well as potential increased mining rates of greater than 2,400 tpd as part of a longer-term expansion scenario.
Magino open pit The Magino open pit will continue to be mined with a conventional shovel-truck methodology. Total mining rates of ore and waste are expected to average 66,400 tpd. Mining rates of ore are expected to average 14,100 tpd over the initial 14 years, with 10,000 tpd to be processed through the Magino mill, and the remaining lower grade ore to be stockpiled for processing at the end of the mine life. The waste to ore ratio mined over the life of mine is expected to average 3.7:1.
Shaft The main components of the shaft infrastructure are unchanged from the Phase 3+ Study with the exception of the crushing facility, which will be installed underground rather than at surface. This change optimizes the flow of ore handling from underground to the mill and reduces the maintenance required for the hoisting system.
A 5.0 metre diameter concrete lined shaft is being constructed with a steel head frame. The skip size has been increased from 12 tonnes in the Phase 3+ Study to 15 tonnes, which will increase the hoisting capacity to 5,500 tpd at the current planned depth of 1,379 metres. This has increased from 4,500 tpd in the Phase 3+ Study and is more than sufficient to accommodate peak mining rates of 4,300 tpd (ore & waste).The shaft will have dedicated compartments for ore and waste movement, and a double-deck service cage for the transport of personnel and materials. The hoisting plant is designed for an ultimate depth of 2,000 metres providing flexibility to accommodate future exploration success.
The underground ore and waste handling and loading pocket will be a conventional configuration similar to that at Young-Davidson. Once skipped to surface, crushed ore will be trucked to the expanded Magino mill.
Paste plant As outlined in the Phase 3+ Study, a paste plant and underground paste distribution system is being constructed. This will allow for faster stope cycling, thereby supporting higher underground mining rates and providing increased geotechnical stability. It will also increase mining recovery resulting in an additional 140,000 ounces of gold recovered over the life of mine. Further, 65% of tailings will be placed underground reducing tailings dam raise requirements over the mine life.
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Mobile fleet – Island Gold Underground mining rates are expected to ramp up from current rates of 1,200 to 1,400 tpd by the end of 2025. Mining rates are expected to further increase to design rates of 2,400 tpd by the end of 2026, driven by the completion of the Phase 3+ Expansion. This will be supported by a significantly smaller truck fleet than required under the current ramp operation.
Post completion of the shaft, a total of seven haul trucks will be required to support a mining rate of 2,400 tpd, compared to a peak of 20 haul trucks required to sustain ramp haulage at 1,200 tpd. This will contribute to the lower ventilation requirements, significantly lower diesel usage, and lower costs given the productivity improvements and economies of scale.
Mobile fleet – Magino The fleet at Magino consists of 15 haul trucks with a payload capacity of 139 tonnes, combined with three diesel powered hydraulic shovels and one excavator, supported by three front-end loaders. The current mobile fleet can support peak mining rates of 74,000 tpd of ore and waste. Decreasing GHG emission intensity The completion of the Phase 3+ Expansion is expected to reduce the Island Gold District GHG emissions intensity from already low levels. In 2024, the Island Gold District emission intensity was 57% lower than the industry average. The transition to a shaft operation from hauling ore to surface, and fully connecting the Magino mill to the electric grid, is expected to drive a further 29% decrease in GHG emissions per ounce produced. This will represent an emission intensity 70% lower than the industry average.
1. Source: S&P Global – Primary Gold GHG Emissions Intensities Decline – December 10, 2024
Processing and Infrastructure
The Base Case LOM Plan reflects the use of the larger centralized mill and tailings facility at Magino. With ore from Island Gold underground to be processed at lower operating costs through the larger Magino mill starting in 2025, the current Island Gold mill and tailings facility will no longer be required.
Current Magino Mill Design The Magino mill includes a crushing circuit that consists of a primary jaw crusher and a secondary cone crusher followed by a semi-autogenous (SAG) mill and ball mill. A cyclone separates the feed sending it to either a gravity circuit where course gold is removed or pumped to the leach circuit where it is thickened and oxygen, lime and cyanide are added for cyanidation. The carbon-in-pulp (CIP) circuit recovers the dissolved gold from the leached slurry.
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The gravity concentrate is processed via an intensive leach reactor. Loaded carbon is acid washed and then undergoes carbon stripping to recover the gold through electrowinning and smelting with the final product being gold doré.
Two successful batch tests of Island Gold ore through the Magino mill were completed in the third quarter of 2024 and April 2025. In both instances, Island Gold ore was blended with Magino ore and processed through the Magino mill with recoveries in line with expectations. With the successful batch tests, and the Magino mill continuing to ramp up towards 11,200 tpd, the Company expects to transition to processing Island Gold ore through the Magino mill in the third quarter of 2025.
The mill feed is based on a 9:1 blend ratio of Magino and Island Gold ore at a combined throughput of 11,200 tpd. Island Gold ore feed will start at 1,200 tpd, increasing to 1,400 tpd by the end of 2025. Magino ore feed will fluctuate between 9,200 tpd and 10,000 tpd. The overall gold recovery from the blend is expected to be approximately 96%.
Expansion to 12,400 tpd To accommodate the increased underground mining rates from Island Gold of 2,400 tpd following completion of the Phase 3+ Expansion in 2026, a number of improvements will be implemented to support increased milling rates within the Magino mill of 12,400 tpd. Many of the changes are being designed and sized to accommodate a potential further expansion of the mill to between 18,000 and 20,000 tpd. The key additions include:
- New underground crusher at Island Gold. Ore will be crushed underground and then trucked to the Magino mill minimizing crushing requirements within the mill
- Pebble crusher and auxiliary mill are expected to be added to the Magino grinding circuit to grind material from the SAG mill and ball mill, respectively
- New gold recovery plant will be added to support increased gold production and will include pre-oxidation, leaching carbon-in-leach, elution, electrowinning and smelting
- The new mill building is being designed to allow space for the addition of a second SAG and ball mill to the overall circuit to support a potential further expansion of the mill up to 20,000 tpd
- CIP tanks within the plant are being sized to accommodate up to a 20,000 tpd processing rate
- The foundation is being sized to hold four additional leach tanks in support of expanding to 12,400 tpd as well as more tanks for a potential larger expansion of up to 20,000 tpd
- The new gold room is being designed to support a potential expansion up to 20,000 tpd
Ore from Island Gold underground will be hauled to the Magino mill on the recently completed 6.5 kilometre road connecting the shaft area to the Magino mill. The ore feed blend will include 2,400 tpd of underground ore and 10,000 tpd of open pit ore with overall recoveries from the expanded circuit expected to average 96.3%.
The expansion of the Magino mill is expected to be completed in the third quarter of 2026 to coincide with the completion of the Phase 3+ Expansion at Island Gold.
12 | ALAMOS GOLD INC