Marimaca Copper Advances MOD Toward Construction Decision Across Six Parallel Workstreams

• Marimaca Copper submitted its critical sectoral permits to Chile's Servicio Nacional de Geología y Minería (SERNAGEOMIN) in April 2026, on schedule, with approvals required to commence all pre-Final Investment Decision (FID) construction activities targeted in the fourth quarter of 2026.
• On May 13, 2026, the National Electric Coordinator granted the Company an electrical connection authorisation to the 110-kilovolt El Lince Line, located approximately 13 kilometres from the Marimaca Oxide Deposit (MOD) project area, subject to a standard 15-day challenge window prior to confirmation.
• Marimaca signed a non-binding Memorandum of Understanding (MOU) with a large-scale sulphuric acid plant operator in Mejillones to evaluate a joint-venture framework for self-supplying acid via the company's previously acquired Dos Amigos Acid Plant (PADA Plant), with the evaluation phase expected to last up to six months.
• Provisional easements covering all surface rights required for the MOD and its associated infrastructure, as defined in the 2025 Definitive Feasibility Study (DFS), have been secured, with final grant and completion of rate negotiations with the Chilean Government targeted in the third quarter of 2026.
• Endeavour Financial has formally launched the MOD debt financing process, with Marimaca targeting announcement of a final funding strategy by the fourth quarter of 2026, against a 2025 DFS pre-production capital expenditure (capex) of US$587 million and a post-tax net present value (NPV) of US$709 million at a long-term copper price of US$4.30 per pound.

Permitting & Surface Rights Underpin Construction-Ready Timeline

Marimaca Copper (TSX: MARI) submitted its critical sectorial permits to Chile's Servicio Nacional de Geología y Minería (SERNAGEOMIN) in April 2026, in accordance with the schedule established following receipt of the environmental approval, Resolución de Calificación Ambiental (RCA) in November 2025. The submitted package includes the Closure Plan, the Open Pit Mining Method approval, and authorisations required to construct the crushing plant, leaching pads, and waste and ripios storage facilities. Approvals are targeted for the fourth quarter of 2026; receipt of approvals would permit the company to commence all pre-Final Investment Decision (FID) construction activities at the Marimaca Oxide Deposit (MOD).

Marimaca secured provisional easements across all surface rights required for the MOD and its associated infrastructure, consistent with the 2025 Definitive Feasibility Study (DFS) layout. The provisional easements provide the Company with certainty of land access across key project infrastructure areas and further support the continued advancement of development activities and the planning of project execution. The final grant, subject to completion of rate negotiations with the Chilean Government, is targeted for the third quarter of 2026.

On May 13, 2026, the National Electric Coordinator granted Marimaca authorisation to connect to the 110-kilovolt El Lince Line, approximately 13 kilometres from the MOD project area. The authorisation is subject to a standard 15-day challenge window, after which it will be confirmed.

Engineering Procurement Launched, Early Works Set for June

The formal tender process for the project's lead Integration Engineer was launched in May 2026, with invitations issued to a shortlisted group of globally recognised Engineering, Procurement, and Construction Management (EPCM) firms. The selected party will work alongside Marimaca's Owner's Team as part of an integrated project delivery structure, and detailed engineering tender packages are targeted for release to shortlisted bidders in the coming weeks.

Site crews are targeted to mobilise in June 2026 to commence upgrades to the site access road and the primary intersection with the regional B-12 highway. These early works activities are intended to support efficient site access and enable a rapid ramp-up of full construction following receipt of the remaining key sectoral permits.

Chief Executive Officer of Marimaca Copper, Hayden Locke, commented on the board's commitment to the timeline:

"The board is committed to us moving ahead, and our intentions today are that we're deep into detail design and engineering. We're running our debt financing process. The objective is at the end of this year, we're ready to start early Pre-FID  construction work, and we're starting to march our way towards an eventual FID."

Sulphuric Acid MOU Targets Self-Supply to Reduce Input Cost Exposure

Marimaca signed a non-binding Memorandum of Understanding (MOU) with a large-scale sulphuric acid plant operator in the Mejillones industrial area to evaluate a joint-venture framework for supplying the MOD's acid requirements via the Dos Amigos Acid Plant (PADA Plant), which the company acquired in August 2025. The MOU contemplates the refurbishment, relocation, integration, and operation of the PADA Plant at the Mejillones site. The evaluation phase runs for up to six months, after which the parties may consider forming a definitive joint venture to develop, finance, construct, and operate the plant.

The 2025 DFS modelled sulphuric acid supply from third-party sources; self-production via the PADA Plant would reduce Marimaca's exposure to spot acid pricing and supply disruptions. On the logistics side, elemental sulfur can be stored on open ground and fed directly into a sulfur burner, eliminating the need for the sealed concrete storage infrastructure required for high-purity sulfuric acid, thereby reducing both capital and operating complexity at the MOD site.

Locke described the practical and financial logic of the storage advantage:

"Acid is notoriously difficult to ship and store. Storing 30 to 40 days of acid on your site is expensive; you've got to have huge concrete tanks, and it's a really painful product to store. Elemental sulfur, on the other hand, you can just store it on the surface.  You don't even need to cover it, and then it can be fed straight into your sulfur burner." 

Formation of a definitive joint venture remains conditional on the outcome of the structured evaluation work program and execution of definitive agreements.

Debt Financing Process Formally Launched Against US$587 Million Capex Target

Endeavour Financial, the company's independent debt advisor, formally launched the MOD debt financing process in May 2026. Marimaca is targeting the announcement of the final funding strategy by the fourth quarter of 2026. The 2025 DFS outlined pre-production capital expenditure of US$587 million, with an initial capital intensity of US$11,700 per tonne of copper production capacity, which, according to Wood Mackenzie's first-quarter 2025 global copper project database, ranked among the lowest for comparable greenfield copper development projects.

The 2025 DFS reported a post-tax NPV of US$709 million and a 31% internal rate of return (IRR) at a long-term copper price of US$4.30 per pound, with a 2.5-year payback period and a production target of 50,000 tonnes per annum of copper cathode. The May 19, 2026, update did not revise any of these figures. Beyond the MOD, Marimaca controls the Pampa Medina and Madrugador exploration properties within the Sierra de Medina region, approximately 25 kilometres from the MOD, where an ongoing 30,000-metre drilling program has identified oxide extensions and high-grade sulphide mineralisation at depth that the Company is targeting to grow cathode production capacity beyond the MOD's 50,000 tonne per annum base case.

Locke commented on the rationale for advancing both the MOD and Pampa Medina simultaneously:

 "We do see a significant amount of value to be created while pushing ahead on the MOD and moving towards a construction decision and going to FID and turning ourselves into a producer while exploring in parallel."

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