Arizona Sonoran Charts Solo Path for Cactus Copper Mine

CASA GRANDE, AZ – December 29, 2025 – Arizona Sonoran Copper Company (ASCU) is set to navigate the development of its flagship Cactus Project alone after announcing it will enter discussions to amicably terminate its joint venture option agreement with Nuton LLC, a technology venture backed by mining giant Rio Tinto.

The move marks a significant strategic pivot for the emerging copper developer. Just over two years ago, the partnership with Nuton was heralded as a major de-risking event, promising advanced technology and substantial funding. Now, ASCU will proceed on a standalone basis, placing the full weight of the project's immense potential—and its considerable financial hurdles—squarely on its own shoulders.

In a joint press release, the companies stated they have “mutually agreed to commence discussions in January” for an early termination. While the outcome of these negotiations remains uncertain, ASCU has made its intentions clear: it will push forward independently, leveraging a recently completed and highly positive Pre-Feasibility Study (PFS) as its new blueprint for success.

A Strategic Pivot

The original option agreement, announced in December 2023, was designed to combine ASCU’s promising copper asset with Nuton’s cutting-edge capabilities. Nuton was granted an option to acquire up to a 40% interest in the Cactus Project in exchange for up to US$33 million in funding and the deployment of its proprietary bio-heap leaching technology.

This technology, developed by Rio Tinto over decades, uses naturally occurring microbes to extract copper from challenging primary sulphide ores, promising significantly higher recovery rates, lower water use, and a smaller carbon footprint compared to some conventional methods. The partnership was structured to produce an “Integrated Nuton Case Pre-Feasibility Study,” which was expected to enhance the project's already attractive economics.

The termination of this arrangement means ASCU will forgo Nuton's direct capital injection and its specialized processing technology. Instead, the company will rely on the strength of its own technical plans and its ability to attract capital from the broader market.

The Standalone Path: Risks and Rewards

Proceeding alone is a bold move, but one that ASCU appears well-prepared to make. The company is buoyed by the results of its standalone PFS, filed in November 2025, which outlines a robust, conventional open-pit and underground mining operation using a proven heap leach and Solvent Extraction/Electrowinning (SXEW) process to produce LME Grade A copper cathodes on-site.

The study projects compelling economics, even without Nuton's involvement. It forecasts a post-tax Net Present Value (NPV) of US$2.30 billion and an Internal Rate of Return (IRR) of 22.8%, based on a conservative long-term copper price of $4.25 per pound. The project is projected to have an initial capital cost of $977 million and produce an average of 103,000 tonnes of copper annually over its first decade.

This would position the Cactus Mine as a tier-one asset and potentially the third-largest copper cathode producer in the United States, a critical distinction at a time of rising geopolitical focus on domestic mineral supply chains. While the capital requirement is substantial, ASCU enters this new phase from a position of relative financial strength. As of late 2025, the company reported a strong balance sheet with a low debt-to-equity ratio of just 0.04, providing significant flexibility for future project financing.

The primary reward for taking on the added risk is retaining 100% ownership of a potentially generational copper asset. This gives ASCU and its shareholders full exposure to the project's upside, a particularly attractive proposition in a bullish copper market. The company will now advance a standalone Definitive Feasibility Study (DFS), targeting completion in the second half of 2026, with a final investment decision possible by the end of that year.

A Project for a Copper-Hungry World

The timing of ASCU's strategic shift could not be more opportune. The global demand for copper is surging, driven by the unstoppable momentum of the green energy transition. Electrification, from electric vehicles and their charging infrastructure to vast solar and wind farms, is incredibly copper-intensive. Global demand is forecast to climb from around 25 million tonnes today to over 36 million tonnes by 2031, creating a projected supply deficit of more than 6.5 million tonnes.

This supply-demand imbalance has led to bullish price forecasts, with some analysts at major banks like UBS and Goldman Sachs predicting copper could trade between $11,000 and $15,000 per tonne in the coming years. The Cactus PFS base case of $9,370 per tonne ($4.25/lb) appears conservative against this backdrop, suggesting significant potential for even stronger economic returns.

As a large-scale, long-life project located in the stable jurisdiction of Arizona, the Cactus Project is precisely the type of asset the world needs to bridge the looming supply gap. Its location on private land is another key advantage, expected to streamline the state-led permitting process and avoid the lengthy federal reviews that can delay projects on public lands for years. With existing infrastructure, including highways, rail lines, and permitted water access, the project is significantly de-risked from a logistical standpoint.

The Path Forward

While the dissolution of a partnership with a global major like Rio Tinto might typically spook investors, market sentiment toward ASCU has been exceptionally strong. The company's stock was trading near a 52-week high prior to the announcement, largely on the strength of its standalone PFS results. This suggests investors already had confidence in the project's viability independent of the Nuton partnership.

The mutual agreement to discuss an “amicable” termination signals a strategic realignment rather than a contentious dispute. For junior mining companies, such early-stage agreements are often fluid, evolving as a project's technical and financial details become clearer. By taking full control, ASCU can now steer the project's development without the complexities of a joint venture structure.

Arizona Sonoran’s focus now shifts entirely to execution. The company plans to continue advancing permitting amendments, project financing work, and other early development activities in the new year, all aimed at hitting its aggressive 2026 targets for a completed DFS and a final investment decision. The journey is now a solo flight, but with a world clamoring for copper, the destination remains as compelling as ever.