Marimaca Copper MOD Progress Update: 6 Things You Need to Know

Project Overview

Marimaca Copper (TSX: MARI) is a copper developer advancing the Marimaca Oxide Deposit (MOD) in Chile's Antofagasta region, located approximately 25 kilometres from the Port of Mejillones and 40 kilometres from the city of Antofagasta. The company completed its Definitive Feasibility Study (DFS) on August 25, 2025 and received its environmental approval in November 2025. The May 2026 progress update covers six concurrent workstreams: sectorial permitting, electrical connection, engineering tenders and early site works, sulphuric acid supply strategy, surface rights, and project financing, all advancing toward a Final Investment Decision (FID).

1. Sectorial Permits Are Submitted & Tracking a Fourth Quarter 2026 Approval Window

Following receipt of the RCA in November 2025, Marimaca submitted critical sectoral permits to Chile's Servicio Nacional de Geología y Minería (SERNAGEOMIN) in April 2026, marking the next phase in the MOD permitting process. The submissions cover the closure plan, open pit mining method, and approvals for the crushing plant, leaching pads, and waste and ripios storage facilities. Marimaca is targeting approvals in the fourth quarter of 2026, which would authorise commencement of pre-FID construction activities. The company stated that it will continue to submit the remaining sectoral permits required to support project execution.

2. Electrical Connection Authorisation Removes a Key Infrastructure Dependency

On May 13, 2026, Marimaca was granted authorisation by Chile's National Electric Coordinator (CEN) to connect to the 110-kilovolt El Lince Line, located approximately 13 kilometres from the MOD project area. The authorisation was subject to a 15-day challenge window as of the announcement date, after which it becomes confirmed. The El Lince Line connection provides the MOD with access to Chile's national grid, which, under the DFS, is to be supplied under a certified renewable electricity contract.

According to the 2025 DFS prepared by Ausenco and NCL, the MOD has an initial capital intensity of US$11,700 per tonne of copper production capacity. That figure compares to US$13,400 per tonne for Costa Fuego, US$15,000 per tonne for Vizcachitas, US$17,100 per tonne for Santa Cruz, and US$21,800 per tonne for Santo Domingo, with only El Pilar at US$9,400 per tonne ranking lower among the six projects in the WoodMac first quarter 2025 global copper project database.

3. Engineering Tenders Are Live & Early Site Works Are Targeting June Mobilisation

The formal launch of the engineering, procurement, and construction management (EPCM) firm tender process and the planned June 2026 mobilisation of early site works crews place Marimaca on a path where detailed engineering and physical site preparation are running concurrently, compressing the timeline between FID and construction commencement.

Marimaca has issued invitations to a shortlisted group of globally recognised EPCM firms to compete for the role of lead Integration Engineer. The selected party will work alongside the Marimaca Owner's Team within an integrated project delivery structure. Detailed engineering tender packages are targeting release to shortlisted bidders in the coming weeks.

Site works crews are targeting June 2026 mobilisation to commence upgrades to the site access road, followed by improvements to the primary intersection with the regional B-12 highway. These activities support site access ahead of full construction and are designed to enable a rapid ramp-up once the remaining key permits are received.

Chief Executive Officer of Marimaca Copper, Hayden Locke, framed the company's current development posture:

"The board is committed to us moving ahead, and our intentions today is 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 when we're ready."

4. The Sulphuric Acid Strategy Introduces a Self-Supply Option With a Cited Payback of 12 to 14 Months

Marimaca has signed a non-binding Memorandum of Understanding (MOU) with a Mejillones-based sulphuric acid plant operator to evaluate a joint venture centered on the company's previously acquired Dos Amigos Acid Plant (PADA Plant); under current spot acid pricing, management has cited a self-produced cost of under US$250 per tonne against a spot price above US$400 per tonne, implying a payback of 12 to 14 months on the self-supply investment.

Sulphuric acid is a direct operating cost in heap leach copper production, and the MOD's 2025 DFS first-five-year steady state C1 cash cost of US$1.45 per pound copper was calculated using long-term consensus spot acid price forecasts. The MOU contemplates evaluating the refurbishment, relocation, integration, and operation of the PADA Plant in the Mejillones industrial area, approximately 25 kilometres from the MOD site, through a structured work program of up to six months that covers multiple development alternatives.

At this stage, the MOU is non-binding, and no definitive agreements have been executed. If a joint venture is subsequently formed, the company asserts that delivery on a just-in-time basis would become available, and that elemental sulfur storage on open ground would replace the requirement for covered tanks for high-purity sulphuric acid, thereby removing a storage infrastructure cost. 

One tonne of elemental sulfur produces three tonnes of sulphuric acid, which Locke identified as the chemical relationship underpinning the cost differential:

 "So as an example today, the spot price for acid as a result of what's happening in Iran or the straits of all, is a bit over $400 a ton, but on a self-produced basis, our numbers are that we could produce it for less than $250. There is a very clear reason why it makes economic sense for us, and based on today's prices, you pay yourself back in 12 to 14 months."

5. All Surface Rights Required Under the DFS Have Been Secured

Marimaca has secured provisional easements covering all surface rights required for the development of the MOD and its associated infrastructure as defined in the 2025 DFS, removing land access as a variable that could delay construction ahead of FID. The provisional easements cover all key project infrastructure areas across the full DFS-defined project footprint. The final grant of the easements is targeted for the third quarter of 2026, following completion of final rate negotiations with the Chilean government, which owns or controls the majority of the land in the project area.

6. Marimaca Launches Formal Financing Process

Endeavour Financial, Marimaca's independent debt advisor, has commenced formal engagement with a broad range of potential financing partners, with Marimaca targeting announcement of the MOD's final funding strategy by the fourth quarter of 2026. Marimaca entered this process with US$165.6 million in cash and no debt as of February 2026, against a pre-production capital expenditure (capex) requirement of US$587 million per the 2025 DFS.

The 2025 DFS outlines a 13-year open-pit, heap-leach, and solvent extraction-electrowinning (SX-EW) operation targeting steady-state production of 50,000 tonnes of copper cathode per year. The DFS underpins the financing case with a post-tax net present value at an 8% discount rate (NPV8%) of US$709 million at a long-term copper price of US$4.30 per pound, a post-tax internal rate of return (IRR) of 31%, and a 2.5-year payback period. At the COMEX 3-month average copper price of US$5.05 per pound as of August 25, 2025, the post-tax NPV8% increases to US$1.1 billion, and the IRR rises to 39%. 

Key Takeaways for Investors

• The two highest-profile workstreams - sectoral permitting and debt financing - are both targeting a fourth-quarter 2026 resolution.
• The Marimaca Oxide Deposit's capital intensity of US$11,700 per tonne of copper production capacity is the second-lowest among six globally benchmarked copper development projects in the WoodMac first quarter 2025 database, with only El Pilar at US$9,400 per tonne ranking lower; parallel to this, the electrical connection authorisation secured in May 2026 formalises the project's grid access.
• The sulphuric acid self-supply evaluation, if resulting in a joint venture, targets a reduction in acid cost from a current spot price above US$400 per tonne to a self-produced cost of under US$250 per tonne - a differential not captured in the 2025 Definitive Feasibility Study's C1 cash cost of US$1.45 per pound copper in the first five years of steady state production.
• Provisional easements covering the full Definitive Feasibility Study footprint are in place, with final grant targeting the third quarter of 2026 pending rate negotiations with the Chilean government.
• Marimaca enters the formal debt financing process with US$165.6 million in cash and no debt, against a pre-production capital expenditure requirement of US$587 million, with a 2025 Definitive Feasibility Study post-tax net present value of US$709 million at US$4.30 per pound of copper and US$1.1 billion at US$5.05 per pound of copper.

The Bottom Line

Six workstreams moved forward in parallel between November 2025 and May 2026: environmental approval received, sectoral permits submitted, grid access authorised, EPCM tenders launched, surface rights provisionally secured, and debt financing formally commenced. What remains unresolved are the sectoral permit approvals from SERNAGEOMIN, the final easement grant from the Chilean government, the selection of the EPCM firm, and the announcement of the funding structure. The next near-term catalyst is the conclusion of the sulphuric acid evaluation, targeting completion within six months of the MOU signing, which will determine whether the MOD's C1 cash cost base can be reduced below the 2025 DFS first-five-year figure of US$1.45 per pound of copper.