South Africa-based Sibanye-Stillwater will establish a joint venture company with Australia-based ioneer with respect to ioneer’s Rhyolite Ridge Lithium-Boron Project. Sibanye-Stillwater will contribute US$490 million for a 50% interest in the joint venture, with ioneer maintaining a 50% interest and retaining the operational management responsibility for the joint venture.

The overall site plan for the Rhyolite Ridge Project. The compact project site extends from the mine quarry in the west to the processing facilities and spent ore storage facility (SOSF) in the east. The processing facilities are approximately 1.8 miles northwest of the quarry and 1 mile north of the spent ore storage facility.

In addition, Sibanye-Stillwater agreed to take a 7.1% stake in ioneer’s ordinary share capital post-placement for approximately US$70 million. Together with the ioneer placement, the joint venture represents Sibanye-Stillwater’s third announced transaction in the battery materials sector following the Keliber lithium and Sandouville nickel transactions.

The joint venture provides Sibanye-Stillwater with a 50% interest in a strategic lithium-boron asset in the US, positioning Sibanye-Stillwater for value creation and growth in the US battery metals supply chain.

Rhyolite Ridge is a large, shallow lithium-boron deposit, located close to existing infrastructure. Rhyolite Ridge is expected to be one of the first large-scale US lithium projects to enter production, currently anticipated in H2 2024.

The Rhyolite Ridge Definitive Feasibility Study, completed in April 2020, supports (100% project basis):

• 22 ktpa lithium hydroxide and 174 ktpa boric acid average production;

• 26-year mine life underpinned by 0.6 mt lithium carbonate and 5.3 mt boric acid of Ore Reserves and 1.25 mt lithium carbonate and 11.9 mt boric acid of Mineral Resources;

• First quartile cost position (after boric acid revenue credits);

• Strong ESG credentials, with a small mine footprint and a clear competitive advantage from a CO₂ emissions and water usage perspective relative to other projects; and

• Net Present Value (8%) of US $1.3 billion.

The mining operations will consist of a conventional drill-and-blast, load-and-haul operation. Ore will be trucked from the mine quarry to the nearby ore processing stockpile over a new heavy haul road. The ore will be reclaimed by a loader and fed to the crushing plant.

Development of the Rhyolite Ridge quarry will occur in two stages:

• Quarry Stage 1 - Starter Pit. An initial starter pit will be developed in the southwestern part of the ore body to supply ore for the first 4.5 years of the Project. In this area, lithium grades are 15% higher than the average grade for the deposit and the ore is more exposed at surface.

• Quarry Stage 2. Development of the greater pit will start once the environmental permits for this development have been granted. The Stage 2 pit design will facilitate a larger mining area to be maintained, aiding the efficiency of the operation for another 21 years. Stage 2 will involve expansion to the south and east. Finally, mining will progress to the north of the deposit. The Stage 2 pit requires prestripping to begin in year 4.

ioneer planned to become the first greenfield site in the US to use automated haul trucks in the initial operation. To minimize the effects of loss and dilution in the mining operation, an accurate geologic model, high-precision GPS, competent operators, and a fleet management system (FMS) will be used. These packages will allow excavator and wheel loader operators to know in real time what type of material is being loaded.

Ore processing facilities and sulfuric acid plant - general layout

Sibanye-Stillwater’s battery material strategy is primarily focused on the United States and Europe in recognition of the developing need for battery metals for the transition towards greater electrification of their established automotive industries. Consistent with this, the US Government has declared lithium as critical to economic and national security and has called for the development of US critical metal processing and refining capacity.