Marimaca Copper Reports MOD Progress on Permits, Electrical Connection & Acid MOU

• Marimaca Copper reported a progress update on permitting and development activities at the Marimaca Oxide Deposit (MOD), stating that critical path items remain on schedule for 2026 as it advances toward a Final Investment Decision (FID).
• Sectoral permits covering the Closure Plan, Open Pit Mining Method, and core infrastructure were submitted to Chile's Servicio Nacional de Geología y Minería (SERNAGEOMIN) in April 2026, with approvals expected in the fourth quarter of 2026.
• On May 13, 2026, the company was granted electrical connection authorisation to the 110kV El Lince Line, located approximately 13 kilometres from the MOD project area, subject to a 15-day challenge window.
• Marimaca signed a non-binding Memorandum of Understanding (MOU) with a large-scale sulphuric acid plant operator and supplier in the Mejillones industrial area to explore a joint-venture framework for supplying the MOD's future sulphuric acid requirements, incorporating the company's previously acquired Dos Amigos Acid Plant (PADA Plant).
• Provisional easements covering all surface rights required for the MOD and its associated infrastructure, as contemplated in the 2025 Definitive Feasibility Study (DFS), have been secured, with final grant expected in the third quarter of 2026.

Company Overview

Marimaca Copper (TSX: MARI) is a copper exploration and development company focused on the Marimaca Oxide Deposit (MOD) and the Pampa Medina project in the Antofagasta Region of northern Chile. The company holds a tenement package of approximately 14,500 hectares at the broader Sierra de Medina project area, comprising a mix of mining and exploration concessions held through its subsidiaries ICAL and SCM Elenita.

Sectorial Permitting

Following receipt of the MOD Environmental Approval (RCA) in November 2025, the company completed the scheduled submission of the project's critical sectoral permits to SERNAGEOMIN in April 2026. The submitted permits include the Closure Plan, Open Pit Mining Method, and several additional approvals required for construction of core project infrastructure, including the crushing plant, leaching pads, and waste and ripios storage facilities.

Submissions were completed on schedule, with approvals expected in the fourth quarter of 2026. The company stated that receipt of these approvals represents a major development milestone for the MOD and would permit the full commencement of all pre-FID construction activities. The company stated it will continue advancing and submitting the remaining sectoral permits required to support the timely development and execution of the MOD.

Electrical Connection

On May 13, 2026, Marimaca was granted electrical connection authorisation by the National Electric Coordinator (CEN) to the 110kV El Lince Line, located approximately 13 kilometres from the MOD project area. The connection authorisation is subject to a 15-day challenge window, after which it will be confirmed.

Engineering Tender & Early Site Works

The tender process for the project's lead Integration Engineer has been formally launched, with invitations issued to a shortlisted group of globally recognised engineering, procurement, construction, and management (EPCM) firms. The selected party will work alongside the Marimaca owner's team as part of the integrated project delivery team to support the execution of the MOD. Subsequent detailed engineering tender packages are expected to be released to the shortlisted bidders in the coming weeks.

Preparations for early site works are progressing, with crews expected to mobilise in June 2026 to commence upgrades to the site access road, followed by improvements to the primary intersection with the regional B-12 highway. The company stated these early infrastructure activities are intended to support efficient site access and enable a rapid ramp-up of full construction activities following receipt of the remaining key permits and approvals.

Sulphuric Acid Strategy

Marimaca signed a non-binding MOU with a large-scale operator and supplier of sulphuric acid in the Mejillones industrial area to explore a framework for a joint venture to supply the MOD with its future sulphuric acid requirements. The MOU contemplates the optimal utilisation of the company's previously acquired PADA Plant, including evaluation of its refurbishment, relocation, integration, and operation in Mejillones.

Self-supplied sulphuric acid through the PADA Plant represents a strategic advantage for the MOD, providing a hedge against volatility in the third-party acid market and the potential to lower acid costs, improve cost predictability, and support operating margins over the life of the project, while retaining flexibility to supplement supply from external sources. The company also stated that self-produced acid in Mejillones would allow just-in-time receipt of acid and reduce the transport and storage complexity of the MOD's acid supply, noting a logistical and storage advantage associated with shipping and storing elemental sulfur compared to high-purity sulphuric acid.

The evaluation phase under the MOU includes a structured work program over an initial period of up to 6 months, during which multiple development alternatives will be assessed. Subject to the results of the evaluation and execution of definitive agreements, the parties may subsequently consider forming a joint venture to develop, finance, construct, and operate the PADA Plant.

Surface Rights

Marimaca stated that provisional easements have been secured covering all surface rights required for the development of the MOD and its associated infrastructure, as contemplated in the 2025 Definitive Feasibility Study (DFS). The company stated that the provisional easements provide land access certainty across key project infrastructure areas. Final grant of the easements is expected in the third quarter of 2026, following completion of final rate negotiations with the Chilean Government.

Project Financing

Marimaca's independent debt advisor, Endeavour Financial, has formally commenced the debt financing process and is currently engaged with potential financing partners to support the development and construction of the MOD. Marimaca will provide further updates in due course and intends to announce the final funding strategy for the MOD by the fourth quarter of 2026.

President and Chief Executive Officer of Marimaca Copper, Hayden Locke, commented:

"We have continued to systematically de-risk the MOD across the key workstreams required to support a construction decision. Our permitting, surface rights and engineering progress, and ongoing engagement with project financing stakeholders all represent important milestones as we move steadily toward construction-ready status and a future FID."

Locke added:

"In parallel, our evaluation of a potential integrated sulphuric acid solution in the Mejillones Industrial Area has the potential to deliver meaningful strategic and operating benefits to the project, including lower costs, enhanced supply security, improved logistics and greater protection against acid market volatility. Together, these initiatives continue to strengthen the overall execution readiness and long-term competitiveness of the MOD."

Next Steps

The company stated the following milestones are targeted: EPCM detailed engineering tender packages to be released to shortlisted bidders in the coming weeks; early site works crew mobilisation in June 2026; final grant of surface rights easements in the third quarter of 2026; sectoral permit approvals and announcement of the final MOD funding strategy in the fourth quarter of 2026. The evaluation period under the sulphuric acid MOU is up to 6 months.

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