Rhyolite Ridge lithium/boron project, US – update

Image of drill core high-grade lithium/boron

Photo by ioneer

19th April 2024

By: Sheila Barradas

Creamer Media Research Coordinator & Senior Deputy Editor


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Name of the Project
Rhyolite Ridge lithium/boron project.

Nevada, US.

Project Owner/s
In September 2021, Sibanye-Stillwater entered into an agreement with ioneer to establish a joint venture (JV) company with respect to Rhyolite Ridge. Following the satisfaction or waiver of all conditions precedent, Sibanye-Stillwater will acquire a 50% interest in the JV, with ioneer maintaining a 50% interest and retaining the operational management responsibility for the JV.

Project Description
A definitive feasibility study (DFS), completed in April 2020, has placed Rhyolite Ridge as the (single) most attractive project for the production of lithium carbonate, lithium hydroxide and boric acid globally.

The lithium and boron mineral resource is estimated at 146.5-million metric tonnes, including an ore reserve of 60-million metric tonnes – an increase in the reserve from the previous estimate of 280% over the 26-year life-of-mine (LoM).

The mine plan comprises almost entirely reserve material, with nearly 50% of that being proven ore reserves.

The resource remains open in three directions, allowing for a potential extension to the LoM.

The project will mine 2.5-million metric tons a year of ore over the LoM to produce about 20 600 t/y of lithium carbonate, or about 22 000 t/y of lithium hydroxide and 174 400 t/y of boric acid, on average.

Potential Job Creation
Not stated.

Net Present Value/Internal Rate of Return
The project has an after-tax net present value, at an 8% real discount rate, of $1.265-billion and an unlevered internal rate of return of 20.8%, with a payback of 5.2 years from the start of first production.

Capital Expenditure
The DFS estimates that the total capital expenditure to complete the project will be $785-million, including an 8% contingency.

This represents an increase of $186-million from the PFS.

The US Department of Energy has said it will lend ioneer up to $700-million to develop the mine.

Planned Start/End Date
ioneer expects to start production in 2025 to support urgent requirements for battery materials in the US.

Latest Developments
The US Bureau of Land Management (BLM) has moved a step closer to approving ioneer's Rhyolite Ridge lithium mine.

The BLM plans to publish a draft environmental-impact statement for public review during a 45-day public comment period, ending on June 3, 2024. During the review period, BLM staff will conduct at least one in-person and one virtual public meeting on the proposal.

Meanwhile, the US Fish and Wildlife Service declared the Tiehm's buckwheat flower endangered in 2021. The agency has indicated that ioneer has redesigned the mine to incorporate a protection plan for the flower.

Ioneer MD Bernard Rowe believes the announcement reflects the company's willingness to work with government to protect the flower and develop a domestic source of lithium.

The BLM has said a final decision is expected by the end of the year, after which ioneer would need to close a funding agreement with the Department of Energy and also with South Africa's Sibanye Stillwater.

The Center for Biological Diversity (CBD), a conservation group that has opposed the mine, has said in response to BLM's announcement that it will "take every available measure to protect" the flower.

Key Contracts, Suppliers and Consultants
Fluor (DFS).

Contact Details for Project Information
ioneer, tel +61 2 9922 5800.
Sibanye-Stillwater, tel +27 11 278 9600 or email

Edited by Creamer Media Reporter



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