Highlights

  • Rhyolite Ridge is fully permitted and construction-ready, with Ioneer progressing toward a Final Investment Decision.
  • The updated project plan targets average annual production of approximately 24,500 tonnes of lithium carbonate equivalent and 135,500 tonnes of boric acid during the first 25 years.
  • The project has secured a USD 996 million Loan from the US Department of Energy.
  • Ioneer’s August 2026 update highlighted new strategic partnerships with KIND and Hyundai Engineering and ongoing work with the US Army on advanced boron applications.

Ioneer Ltd (ASX:INR) is moving its 100%-owned Rhyolite Ridge Lithium-Boron Project in Nevada toward the final stages of development after completing federal permitting, securing major government-backed Debt Financing and progressing strategic partner discussions.

Rhyolite Ridge is located in Esmeralda County and is designed to produce two minerals considered strategically important to US Supply chains: lithium and boron. Lithium is central to battery storage and electric mobility, while boron has applications across permanent magnets, semiconductors, defence systems and advanced materials.

The company’s latest substantive project communication came through its August 2026 quarterly newsletter. Ioneer said it was progressing toward a Final Investment Decision and construction while advancing new strategic relationships with KIND and Hyundai Engineering. The update also highlighted collaboration with the US Army to assess advanced boron production for defence applications.

Project Readiness

Rhyolite Ridge is now described by Ioneer as a permitted and construction-ready greenfield development.

Federal approval was secured previously through the Bureau of Land Management, removing one of the major permitting hurdles that had affected the project’s timeline.

The project has also moved well beyond early engineering.

Ioneer states that approximately 70% of engineering work has been completed, providing greater confidence around plant design, construction scope and project costs.

This level of engineering Maturity is important because cost overruns and design changes are common risks when large Mining projects enter construction.

Ioneer’s immediate focus is therefore increasingly centred on finalising the Equity component of project funding and completing the conditions required before a formal investment decision can be made.

Updated Economics

The October 2025 technical update materially improved the Rhyolite Ridge development case.

Following optimisation of leach retention times and reagent efficiency, Ioneer estimates average annual lithium carbonate equivalent production of approximately 24,500 tonnes during the first 25 years.

Average annual boric acid production over the same period is estimated at approximately 135,500 tonnes.

The updated Economics calculate an after-tax unlevered NPV8 of approximately USD 2.24 billion and an unlevered internal rate of return of 18%.

On a leveraged basis, the project has an estimated after-tax NPV8 of approximately USD 2.30 billion and IRR of 23.2%.

Average annual EBITDA during the first 25 years is estimated at approximately USD 563 million.

Cost Position

Boron co-production is central to the project’s economics.

Unlike lithium operations that rely almost entirely on Revenue from a single commodity, Rhyolite Ridge is designed to generate meaningful income from boric acid.

When expected boric acid revenue is treated as a Credit against lithium production costs, Ioneer estimates an All-In Sustaining Cost of approximately USD 4,628 per tonne of lithium carbonate equivalent during the first 25 years.

The company believes this would position Rhyolite Ridge within the lower Quartile of the global lithium cost curve.

Direct C1 costs are estimated at approximately USD 2,933 per tonne of LCE during the same period.

The dual-product model could therefore provide some Earnings Diversification during periods of weaker lithium pricing.

Capital Funding

Rhyolite Ridge remains a capital-intensive project.

The updated AACE Class 2 Capital estimate is approximately USD 1.683 billion, including a 10% contingency.

One of the most important funding milestones occurred in January 2025 when Ioneer closed a USD 996 million loan from the US Department of Energy.

The financing provides a substantial debt foundation for the development and reflects Rhyolite Ridge’s strategic importance to domestic US critical-mineral supply.

Ioneer has also invested more than USD 200 million of private capital into the project to date.

The remaining challenge is completing the broader funding package on terms that allow construction to commence without placing excessive pressure on the company’s Balance Sheet or shareholders.

Strategic Partners

Partnership development has become increasingly important during 2026.

The August update highlighted new relationships with KIND and Hyundai Engineering as Ioneer continues preparations for Final Investment Decision and construction.

Strategic partners can contribute more than capital. They may provide engineering capability, construction expertise, procurement support, Downstream market access or additional confidence for lenders.

Ioneer has also previously secured binding lithium offtake agreements with major downstream customers, helping provide future Demand visibility.

These arrangements reinforce the project’s position within the broader US effort to develop domestic battery-material supply chains.

Boron Opportunity

Boron is becoming a more prominent part of the Ioneer story.

The company’s August 2026 communication highlighted work with the US Army to evaluate advanced boron production for critical defence applications.

Boron can be used in advanced ceramics, body armour and permanent magnets, giving the Commodity strategic importance beyond conventional industrial markets.

Rhyolite Ridge’s ability to produce both lithium and boron from the same orebody and integrated processing circuit differentiates it from most lithium projects.

The updated Ore Reserve contains approximately 2.039Mt of lithium carbonate equivalent and 7.761Mt of boric acid equivalent, providing a long-duration resource foundation.

Processing Design

Rhyolite Ridge uses an integrated processing flowsheet based on conventional commercial technologies adapted to the project’s unique mineralogy.

The ore does not require intensive grinding before leaching, helping reduce energy requirements.

Ioneer’s processing design also emphasises water recycling and on-site energy generation.

The company estimates lithium carbonate recovery of approximately 85%, lithium hydroxide circuit recovery of 95% and boric acid recovery of around 79%.

Extensive bench-scale and pilot work has already been completed to support plant design and operating assumptions.

Final Takeaway

Ioneer has moved Rhyolite Ridge into a more advanced development position than many emerging lithium projects.

The project is fully permitted, has substantial engineering completed and is supported by a USD 996 million US Department of Energy loan.

Updated economics indicate average production of approximately 24,500 tonnes of LCE and 135,500 tonnes of boric acid annually during the first 25 years.

For Ioneer (ASX:INR), the critical next milestone is completing the strategic partnering and funding process required for a Final Investment Decision.

The August 2026 update shows that management is also broadening Rhyolite Ridge’s strategic relevance through new partnerships and potential defence applications for boron.

Successful funding completion would shift investor attention from project preparation toward construction execution and eventual commissioning.