Renascor Resources Validates HF-Free Graphite Purification Option for Siviour Project

Renascor Resources (ASX: RNU) has reported positive results from a cost profile study of its hydrofluoric acid (HF)-free method for purifying graphite from the Siviour project in South Australia to up to 99.99% carbon for use in lithium-ion battery anodes.

The study incorporated engineering data and operating assumptions generated through large-scale purification testwork, process optimisation, water treatment studies, and purified spherical graphite (PSG) demonstration plant development activities.

It estimated that operating costs of approximately US$459 per tonne for HF-free purification could be a compelling alternative to HF-based methods being developed outside China.

The process offers lower reagent costs and reagent recycling by using an integrated water treatment circuit, eliminating the need for the higher costs associated with the use of HF.

Major Operating Cost

Purification of graphite to 99.95% carbon or greater is a critical requirement for lithium-ion battery anode applications, and one of the major operating cost components in downstream PSG production.

Conventional purification methods generally rely on HF acid while downstream costs outside of China can increase significantly due to reagent prices and the extensive health, safety, environmental handling, and disposal requirements associated with the chemical.

Renascor’s HF-free purification process combines sulfuric acid leaching with a low temperature caustic bake plus a water treatment circuit, allowing for the recycling of reagents and limiting water usage.

The process has delivered battery-grade graphite exceeding 99.99% carbon purity through large-scale locked-cycle trials, with no impurities detected above acceptable anode customer specifications.

Integrated PSG Operation

Managing director David Christensen said the company aimed to combine the scale and quality of Siviour with downstream PSG processing to establish an integrated Australian mine-to-PSG operation.

“Our strategy extends the low-cost advantage of Siviour into downstream PSG production to provide anode manufacturers with a secure and commercially competitive source of spherical graphite using the HF-free process,” he said.

“The work currently being done at our PSG plant is intended to validate this value proposition by generating the operating data, cost information, and qualification samples required to support engagement with anode and cell manufacturers, advance customer qualification programs, and progress offtake and strategic partnership discussions.”

Built with the help of a $5 million Australian federal grant, Renascor’s demonstration plant is a key component of its Siviour development strategy, converting spherical graphite into PSG and enabling the company to test, demonstrate, and optimise the process.

The plant is currently being commissioned to validate engineering, operating, and process parameters ahead of a commercial-scale build incorporating learnings relating to purification performance, reagent consumption, water treatment integration, process stability, and product quality under continuous operating conditions.