MOD Feasibility Study Confirms Robust Capital Intensity and 31%+ IRR; Maiden Ore Reserve

2025-08-25

TSX - Toronto Stock Exchange · Copper · Canada

The Full Announcement is Available in PDF here: http://ml.globenewswire.com/Resource/Download/339b9466-3158-4fb4-b347-9e79e7d23bf8

VANCOUVER, British Columbia, Aug. 25, 2025 (GLOBE NEWSWIRE) -- Marimaca Copper Corp. (ARBN 683017094) (“Marimaca” or the “Company”) (TSX: MARI) (ASX: MC2) is pleased to announce the results of the Definitive Feasibility Study (“DFS”) for its Marimaca Oxide Deposit (“MOD”) which considers a nominal 50 ktpa of copper cathode production target for an estimated 13-year reserve life.

The Company will host an investor presentation, covering the DFS, via the Investor Meet Company (“IMC”) platform on August 26, 2025. Further details can be found below.

Highlights

Pre-production capital cost and capital intensity of US$587m and US$11,700/tonne of copper production capacity, respectively, positions the MOD as one of the lowest capital cost and intensity development stage copper projects globally Simple open pit mining with life of mine strip ratio of 0.8:1 including pre-stripped material Steady state (years 2-10) production of approx. 49 ktpa (108 million lbs) of Grade A LME copper cathode First five years of 50ktpa copper, LOM average of 43ktpa copper

First five years of steady state production estimated C1 cash costs of US$1.45/lb; AISC cost of US$1.97/lb Steady state (years 2-10) estimated C1 cash costs of US$1.68/lb; AISC of US$2.09/lb LOM C1 cash costs of US$1.84/lb; AISC of US$2.29/lb

Dynamic geo-metallurgical model with recoveries based on data collected from seven comprehensive phases of metallurgical testing LOM heap leach copper recoveries of 72%, first five years of 78%

Robust forecast economics and strong estimated cashflow generation at various copper prices Post Tax NPV 8 of US$709m (US$900m pre-tax) and IRR of 31% (33% pre-tax) using a long-term copper price of US$4.30/lb copper (slightly below LT consensus), 2.5yr capital payback Post Tax NPV 8 of US$1.07bn (US$1.39bn pre-tax) and 39% IRR (43% pre-tax) at the 3-month rolling average COMEX price of US$5.05/lb

Maiden Proven and Probable Mineral Reserves of 178.6Mt with an average grade of 0.42% CuT for 750kt of contained copper based on Measured & Indicated Resources (i.e. Inferred material currently reports to waste for the purposes of the DFS plan) The Company believes that the MOD DFS represents the starting point in its organic growth strategy with numerous defined growth opportunities Inferred Resource currently treated as waste in the DFS mine plan Pampa Medina and Madrugador Oxides which the Company believes has the potential to underpin a future regional hub-and-spoke oxide opportunity Sulphide exploration potential at both Marimaca and Pampa Medina as demonstrated in recent drilling success

Initial designs include oversized key equipment and infrastructure allowing for cost effective potential future scale expansions including the primary crusher, conveyors, water pipeline and infrastructure, power connection, footprints of the heap leach, and ripios dump The DFS incorporates purpose-built water infrastructure to mitigate risks associated with utilizing existing mine water infrastructure in the region Capital cost estimate is based on approximately 80% budget quotes, including an Engineering Procurement Construction (“EPC”) quote for the SX-EW plant Opportunity to reduce initial capital costs by utilizing an alternative contracting strategy

Project permitting well underway and receipt of environmental approvals (RCA) are anticipated before the end of 2025 Sectoral Permits will be required post-environmental approval to allow full construction to commence and to support the operations phase

Debt financing workstreams are underway, with advisors and technical experts engaged – objective of identifying preferred financing partners by year-end 2025

_Hayden __Locke, __President __& __CEO __of __Marimaca __Copper, __commented: _

“The DFS confirms the MOD’s position as one of the most attractive copper development opportunities globally, especially when compared to those with a production capacity greater than 50ktpa. There are very few copper projects with lower capital intensity, and our competitive operating cost profile, positioned in the second quartile of Wood Mackenzie-benchmarked copper projects globally on an all-in-cost basis, drives superior return on invested capital metrics at virtually any copper price. Cashflows are robust, even at copper prices well below today’s long term consensus copper price, which will support our well progressed debt financing discussions.

“Our base case economics are assessed using a flat long term copper price of US$4.30/lb, which is slightly below the current consensus long term price. We note other recent Feasibility Studies in our developer peer group have used a headline price of above US$4.80/lb. At that price, the MOD delivers nearly US$1bn of post-tax NPV8 with an IRR of 36.5%. This result confirms again that the MOD is quite exceptional from a ROIC perspective.

“We have quoted all material equipment from reputable providers to ensure long term reliability and operability. Massive and civil earthworks were quoted by a large Chilean contractor with expertise in mining earthworks. Quotes for construction and assembly of key packages were received from local and international contractors, including an Engineering Procurement Construction (“EPC”) quote for the SX-EW plant. This passes risk to the contractor but naturally increases the overall cost to the Company. The Company believes there is an opportunity to further optimize the capital cost by utilizing a hybrid contracting strategy.

“Operating costs have been built from first principles and include maintenance schedules recommended by equipment providers over the life of mine. The MOD benefits both from its extremely low life of mine strip ratio, but also its geometry, which means even at the end of the current mine plan, the vertical haulage distance is less than 200m, meaning mining costs are significantly lower both on per tonne of material moved and per tonne of ore delivered to the heap leach pads.”

“The DFS excludes the inferred resources of 21Mt with an average grade of 0.29% CuT. Approximately 10Mt of inferred material is moved as part of the DFS mine plan, all of which reports to waste. We expect, with minimal additional drilling, that we can continue our strong conversion of mineral resources to ore reserves, which is approximately 84% for the Measured and Indicated resource categories.

“We are well progressed on a PEA for Pampa Medina, which has been briefly paused due to recent drilling success, and we now see strong potential to increase our production target scale from the contemplated 50ktpa of copper cathode production with oxides from the Pampa Medina and Madrugador deposits (although no forecast is made of that at this stage). We strongly believe 50ktpa of copper production is a starting point for the Company as we continue our journey towards being a significant global copper producer.

“Our permitting is progressing well and we have now submitted our responses to the first ICSARA (list of questions and clarifications) from the regulatory authorities. We expect one further round of follow-up questions and information requests after which the authorities should be in a position to provide environmental approvals for the MOD. We are targeting receipt of environmental approvals by the end of 2025, allowing construction to commence in 2026.

“The multi-pronged strategy of Marimaca remains to bring the MOD into production as quickly as is feasible, while continuing to progress our pipeline of projects, at various stages of maturity, in parallel. This will include further technical work on the Pampa Medina and Madrugador Projects with the objective of increasing our potential production capacity to over 70ktpa of copper cathode within the next 5 years. In parallel, we will continue to explore high priority targets including the Pampa Medina Deposit, where material possibilities for resource growth have been identified, and to test the sulphide potential below the MOD, which has never been drilled.

“Overall, we are pleased with the results following a significant amount of technical work completed in the last two years. We see opportunities for further improvement to what is already an exceptional project as we progress through detailed design and engineering, and we are excited to commence the next phase of our development.”

Investor Presentation

Marimaca will host an investor presentation via the IMC platform on Tuesday, August 26 2025, covering today’s announcement. The online event will take place at 03:00 a.m. (Vancouver) / 06:00 a.m. (Toronto) / 11:00 a.m. (London) / 6:00 p.m. (Perth) with Hayden Locke (President & CEO) presenting from the Company. The presentation is open to all existing and potential shareholders. Questions can be submitted at any time during the presentation.

Investors can sign up to IMC for free and add to meet Marimaca Copper via:

https://www.investormeetcompany.com/marimaca-copper-corp/register-investor

Executive Summary

The DFS contemplates truck and shovel mining operation to produce ore from a single open pit, three-stage crushing, agglomeration and dynamic heap leaching to produce a target of 50ktpa of copper cathode with an initial 13-year reserve life.

The resource is contained in a single open pit, developed over eight phases. The life-of-mine strip ratio, which includes inferred material as waste and the initial pre-strip, is 0.8:1. Initial throughput of 12 Mtpa of heap leach material expands to 16 Mtpa in the second phase starting in year 6 of the mine plan.

Mineral resources are based on approximately 140 km of reverse circulation and diamond drilling, completed from 2016 to 2022, and the database incorporates sequential copper (acid soluble & cyanide soluble copper), analytical acid consumption and mineralogy. Mineral reserves are based on the Measured and Indicated Resource categories, post the application of various modifying factors, including operating costs, recoveries and mining assumptions.

Ore is crushed via a three-stage crushing configuration to a product size of 80% passing 12.5 mm (-½”). Post crushing, ore is agglomerated and acid cured and stacked on dynamic heap leach pads with maximum lift height of 4 meters. Ore is irrigated with leaching solution comprising of untreated seawater and sulfuric acid. Acid dose in curing, acid concentrations in leaching, overall leaching ratios and leaching periods are variable depending on mineral sub-domain. The mine plan does not consider selective mining of mineralogical domains, but there is natural selectivity within the mine plan based on the geometry and natural domaining of the deposit. The early years comprise dominantly green oxides (brochantite and chrysocolla) moving to more enriched (secondary sulphides comprising chalcocite and covellite) and WAD material in the second half of the mine plan.

Copper recoveries are variable depending on mineral sub-domain. Recovery equations have been developed from seven phases of metallurgical test work, including numerous column leach tests using the operating parameters contemplated in the DFS. Recovery equations are dynamic and dependent on mineral sub-domain, grade, leaching potential and have been assigned on a block-by-block basis within the DFS mine plan. Acid consumption assumptions are also based on all of the phases of metallurgical test work, and utilize the analytical acid consumption database, which has been acquired for all of the 140 km of drilling included in the MOD drilling package.

Capital costs have been estimated on the basis of the material take-offs developed by Ausenco in engineering for quantities and detailed mechanical equipment lists. Budget quotations were obtained for approximately 80% of the mechanical equipment in support of the capital cost estimate. For mechanical equipment, quotes have been obtained from multiple reputable firms. Massive and civil earthworks rates have been obtained from Excon, one of the largest earthmoving contractors in Chile. Construction and assembly costs have been obtained from local Chilean contractors on a procurement and execution basis. The quote for the SX-EW facility was provided by Tenova on an EPC basis.

For the purposes of the DFS, the water and power infrastructure, to the mine gate, have been included on the basis of Build Own Operate Transfer (“BOOT”) proposals provided by local and international firms with presence in Chile. This reduces the upfront capital cost, with the cost reflected as an ongoing operating cost to the Project.

| Metric | Unit | First 5 Years of Steady State ( 1) | First 10 Years ( 2 ) | LOM | | Mining Summary | | | | | | Total Ore Mined | kt | 80,683 | 173,994 | 178,635 | | Total Waste Mined | kt | 73,803 | 144,778 | 145,889 | | Strip Ratio | w:o | 0.91x | 0.83x | 0.82x | | Production Summary | | | | | | Average Annual Ore Sent to Heap Leach | Mtpa | 12.4 | 13.6 | 14.1 | | Head Grade Cu | % Cu | 0.52% | 0.48% | 0.42% | | Cu Recovery | % Cu | 77% | 73% | 72% | | Average Annual Cu Recovered | ktpa Cu | 50 | 48 | 43 | | Operating Costs | | | | | | Mine Operating Costs | US$/t mined | $1.2 | $1.4 | $1.5 | | Processing Costs | US$/t processed | $8.9 | $8.9 | $8.8 | | G&A Costs | US$/t processed | $0.3 | $0.3 | $0.3 | | Total Operating Costs | US$/t processed | $ 12.3 | $ 12.5 | $ 11.9 | | Sales & Royalty | US$/lb Cu | $0.10 | $0.07 | $0.06 | | C1 Cash Costs ( 3 ) | US$/lb Cu | $ 1.45 | $ 1.68 | $ 1.84 | | AISC ( 4 ) | US$/lb Cu | $1.97 | $2.12 | $2.29 | | Capital Expenditures | | | | | | Initial Capital | US$m | $587 | | | | Expansion Capital | US$m | $77 | | | | Sustaining Capital | US$m | $283 | $484 | $529 | | Closure Cost | US$m | $47 | | | | Salvage Value | US$m | $43 | | | | Financial Metrics | | | | | | Long Term Copper Price | US$/lb Cu | $4.30 | | | | Average Annual EBITDA | US$m | $326 | $288 | $241 | | Post-Tax Average Annual Unlevered Free Cash Flow ( 5 ) | US$m | $222 | $188 | $160 | | Pre-tax NPV 8% | US$m | $900 | | | | Post-tax NPV 8% | US$m | $709 | | | | Pre-tax IRR | % | 33% | | | | Post-tax IRR | % | 31% | | | | Payback Period | years | 2.5 | | |

Notes: 1. First 5 years of steady state (Years 2-6) 2. First 10 Years production includes material moved for pre-stripping in Year -1 and ramp-up period in Year 1. 3. C1 Cash Costs includes the mining, processing, G&A, marketing & sales, and royalty costs. These are Non-GAAP performance measures. 4. AISC includes sustaining capex, closure capex, and salvage value. 5. Average Annual Unlevered Free Cash Flow during operating years only (years 1-13)

Table 1: Summary of MOD DFS Production Target and Financial Metrics

Initial Capital Cost

The initial capital cost estimate provides for US$587m for 50 ktpa of copper production capacity per annum, with a capital intensity per tonne of production capacity of US$11,700/tonne.

All capital cost estimates have been developed considering the American Association of Cost Engineers (“AACE”) Class 3 guidelines, with an expected accuracy of of -10% to -20% / +10% to +30%. A contingency of 10%, on average, has been applied across the direct and indirect capital costs of the Project.

Capital costs have been developed using material take-offs (“MTOs”) developed by Ausenco in the DFS engineering which included detailed equipment lists and quantities. Equipment, materials, earthworks and construction were then quoted using reputable local and international firms.

The mining fleet is assumed to be financed under a lease to own arrangement. The water and power infrastructure to the mine gate is assumed to be developed by third parties under a Build Own Operate Transfer (“BOOT”) contract structure with large international and local infrastructure firms operating in Chile.

| Metric | Unit | Total LOM | | Initial Capital Cost | | | | Mine | US$m | $24 | | Crushing | US$m | $141 | | Heap Leach & SX-EW | US$m | $223 | | Infrastructure | US$m | $49 | | Total Direct Costs | US$m | $ 437 | | Indirect costs | US$m | $80 | | Owner costs | US$m | $17 | | Contingency | US$m | $53 | | Total Initial Capital Cost | US$m | $ 587 |

Table 2: Initial Capital Costs for the MOD Project

The estimates for initial capital cost put the MOD among the lowest absolute capital costs and capital intensities for any greenfields copper projects globally. According to Wood Mackenzie’s global copper project database, there are seven projects with lower capital intensity in the developer universe with initial capital more than US$300m and production targets of greater than 100Mlbs of copper per annum. The MOD is among the lowest capital intensity and absolute capital cost copper development projects in this dataset.

Figure 1: Capital Cost Intensity for Global Copper Development Projects in Wood Mackenzie Database Highlighting the MOD’s Attractive Capital Intensity

Operating Costs

Operating costs were built from first principles using schedules for labour, energy consumption, consumables (diesel, lubricants, reagents, acid, water) and equipment manufacturer specified maintenance schedules over the life of mine.

Mining costs were provided via specialist Chilean mining consultancy NCL and were benchmarked against operations with identical fleets and similar mine production profiles operating in Chile. Mining rates were developed from first principles with industry standard assumptions on utilization rates and adjusted for MOD specific operating parameters using a Mining Cost Adjustment Factor (“MCAF”). This accounts for changes in vertical and lateral haulage distances as the open pit develops over the life of mine. Mining operating costs include interest and capital costs associated with a leasing equipment contract structure with Komatsu.

Processing costs were also developed from first principles utilizing schedules for labour, reagent consumption from the geometallurgical model and metallurgical test work. These were applied using the geometallurgical model to account for acid consumption, and for industry standard rates for the SX-EW facility.

| Total Estimated Operating Costs | LOM Total (US$m) | LOM Average (US$/t processed) | LOM Average (US$/lb Cu) | | Mining (excl. deferred stripping) | $498 | $2.79 | $0.42 | | Processing (excl acid) ( 1 ) | $1,037 | $5.80 | $0.87 | | Acid | $530 | $2.97 | $0.45 | | G&A | $53 | $0.30 | $0.04 | | Sub-Total | $ 2,119 | $ 11.86 | $ 1.78 | | Total C1 Cash Cost ( 2) | $ 1.84 | | | | Sustaining Capital Cost | $529 | $2.96 | $0.44 | | AISC ( 3) | $ 2.29 | | |

Notes: 1. Includes cost for Port and BOOT Agreements. 2. C1 Cash Costs includes transport, selling and royalty costs in addition to the sub-total presented. These are Non-GAAP performance measures. 3. AISC includes sustaining capex, closure capex, and salvage value.

Table 3: Total Operating Costs Estimate

The Company has benchmarked the MOD utilizing Wood Mackenzie’s database of 237 operating copper mines. Several of the mines have negative C1 and AISC costs on account of by-product credits. These have been included for completeness of the analysis .

The MOD has projected C1 cash costs for the first five years of steady state operations are US$1.45/lb. For the first 10yrs of operations, including the ramp up period in year 1, C1 cash costs are projected to be US$1.68/lb.

This places the MOD at the bottom end and middle of the 2 nd quartile of the peer group for these periods, respectively, when compared to the benchmarked universe of copper assets, per Wood Mackenzie.

Figure 2: C1 Cash Cost Curve for Operating Copper Mines from Wood Mackenzie Showing Competitive MOD C1 Cost Base in 2 nd Quartile

On an AISC cost basis, the Project has projected costs of US$1.97/lb for the first 5yrs of steady state operation and US$2.09/lb during steady state operations (years 2-10). For the first 10yrs of operations, including the ramp up period in year 1, AISC costs are projected to be US$2.12/lb.

This places the MOD in the bottom of the 2 nd quartile during steady state operations (including ramp-up) when compared to the peer group of benchmarked copper assets per Wood Mackenzie.