ioneer Rhyolite Ridge Lithium-Boron Project

Client: ioneer
Location: Esmeralda County, NV, U.S.

Executive Summary

Fluor was selected by ioneer to perform the definitive feasibility study (DFS) and subsequently, engineering, procurement and construction management (EPCM) services as the project progresses for its Rhyolite Ridge Lithium-Boron Project in Esmeralda County, Nevada.

Rhyolite Ridge holds the largest known lithium and boron deposit in North America, estimated at 146.5 million metric tonnes, including an ore reserve of 60 million metric tonnes. ioneer expects to mine and process 63.8 million metric tonnes over the 26-year mine life at an average annual rate of 2.5 million metric tonnes per year.

Client's Challenge

The global lithium market is expanding rapidly due to an increase in the use of lithium-ion batteries for electric vehicle and energy storage applications. Boron is widely used in the glass industry to strengthen and increase heat resistance for glass cookware, laboratory glassware and glass screens used in mobile phones, tablets and liquid crystal display televisions. Boron is also used in fiberglass, insulation, electronics and as a micronutrient in agriculture.

Rhyolite Ridge is poised to become a globally significant, long-life, low-cost source of lithium and boron vital to a sustainable future. The resources onsite have the potential to make a positive environmental and economic impact locally, nationally and globally.

Fluor's Solution

Fluor served as the engineering partner for ioneer during the DFS. The study confirmed that the project has a stable overall operating cost structure for the production of lithium carbonate and battery-grade lithium hydroxide due to the scale and reliability of its boric acid credit.

Fluor further developed and refined project plans in the DFS to a 30% engineering complete level. The refinement of the DFS as compared to the pre-feasibility study is substantial and helps ensure predictable, sustainable and low operating costs over the life of the project. An important addition to the prior scope is the upfront inclusion of a steam turbine for power generation, which will provide the entire operation enough energy to be fully self-sufficient.


Completed in April 2020, the DFS validates Rhyolite Ridge as a world-class resource with significant value creation potential due to its low-cost, large-scale operation and long mine life. Production is planned to commence by the middle of 2023, with an expected 26-year mine life and the opportunity to extend and expand.