South32 Extends Hermosa Taylor Mine Life with 52% Reserve Increase

Taylor Deposit Expansion and Mine Life Extension

South32 Limited (ASX:S32) has unveiled a major update on its Hermosa project in Arizona, spotlighting a 52% surge in the Taylor zinc-lead-silver Ore Reserve to 99 million tonnes. This uplift, driven by successful infill drilling, has extended the initial operating life of the Taylor mine by five years to approximately 33 years. The deposit remains open in multiple directions, hinting at further growth potential beyond the current mine plan, subject to regulatory approvals.

Alongside Taylor, the adjacent Peake copper deposit saw a 32% increase in its Mineral Resource estimate to 33 million tonnes, underpinning South32's expectation that Peake will contribute copper production and extend the overall mine life within the Taylor development. This integration aligns with the design of the Taylor process plant, which includes flexibility for a future copper circuit addition.

Production Schedule and Construction Challenges

First ore from Taylor is now anticipated in the second half of fiscal year 2028, with nameplate capacity of 4.3 million tonnes per annum expected by fiscal year 2031. This marks a delay from earlier forecasts, primarily due to contractor underperformance and productivity challenges in shaft construction. Despite targeted measures such as enhanced contractor leadership and specialist advisors, South32 acknowledges these interventions will only partially mitigate the delays.

The company has leveraged the recently completed Clark deposit exploration decline to provide additional access to the Taylor orebody, enabling first production ahead of shaft commissioning and boosting ore handling capacity by about 25%. This integrated underground development approach could potentially increase production beyond current design rates, pending surface infrastructure optimisations over the next year.

Capital Expenditure and Cost Inflation

Growth capital expenditure for Taylor has been revised upward to approximately US$3.3 billion, reflecting scope additions such as the decline access, revised shaft construction costs, and significant inflationary pressures. Industry-wide cost escalations in steel, piping, concrete, electrical components, and US tariffs have collectively added around US$1 billion to the capital budget since the final investment approval in early 2024.

Operating unit costs have also increased to about US$100 per tonne of ore processed, up from prior estimates, due to general inflation and higher energy costs. Sustaining capital expenditure is forecast to average around US$50 million annually over the mine life, including continued investment in underground infrastructure.

Financial Outlook and Commodity Price Sensitivity

Despite cost pressures and schedule adjustments, Taylor remains a high-quality, long-life project with strong financial metrics. South32 projects steady-state EBITDA of approximately US$650 million per annum and a net present value (NPV) of around US$3.1 billion at long-term commodity prices. At spot prices as of April 2026, these figures improve to about US$800 million EBITDA and US$4.5 billion NPV, underscoring the project's significant leverage to zinc, lead, and silver prices.

The production profile anticipates 10.4 million tonnes of payable zinc equivalent over the mine life, including 3.7 million tonnes of zinc, 4.6 million tonnes of lead, and 247 million ounces of silver. Annual average steady-state production is expected at 346,000 tonnes zinc equivalent, slightly lower than previous feasibility study estimates due to grade adjustments but compensated by increased tonnage.

Infrastructure and Permitting Progress

Construction milestones include the completion of the exploration decline for the Clark manganese deposit, supported by US government grants recognising its strategic importance for battery-grade manganese supply. The Clark decline not only facilitates manganese development but also enhances access to Taylor, improving operational flexibility.

South32 is advancing permitting under the US federal FAST-41 process, designed to streamline critical infrastructure projects. Federal approvals for the Taylor mine plan are on track for the first half of fiscal year 2027, with all state approvals secured. The project benefits from established infrastructure such as water treatment plants and a 138kV transmission line, with ongoing efforts to secure renewable energy sources.

Exploration Upside and Regional Prospects

Beyond the core deposits, Hermosa's extensive land package hosts a highly prospective corridor with over 15 identified exploration targets. Notably, the Flux prospect, located 5km from Taylor, has returned high-grade polymetallic drill intersections, indicating potential for Taylor-like mineralisation. South32 plans to prioritise permitting and drilling of these prospects to fuel future growth phases.

This update builds on South32's recent operational progress and strategic positioning in critical minerals, following a quarter marked by operational challenges but continued advancement of Hermosa's development South32 Navigates Fatal Incident. The increased capital allocation and revised schedule also come in the wake of the company's strong financial performance earlier in the year South32 Boosts Profit 29%, underscoring the group's commitment to long-term value creation despite near-term hurdles.