Electrochemical mineral carbonation for more sustainable mining

Project duration: 1 July 2023–30 June 2026

Project lead

Team

Yuan Mei, Liang Liu, Xingrui Chen and Lauren Zappala.

Opportunity

The mining industry has major sustainability challenges with emissions reduction and effective management of the large volumes of tailings and waste produced by its activities. Worldwide, high emissions, and tailings storage and handling pose major environmental issues.

While mineral carbonation (MC) via the reaction of carbon dioxide (CO₂) with mafic/ultramafic rocks (in-situ MC) or the tailings from mineral processing (ex-situ MC) occurs naturally, the reaction is too slow for this to be a practical pathway for climate change mitigation. Existing ex-situ MC technologies are energy intensive and costly, and require the use of many additional chemicals. Sustainable methods for significantly accelerating the MC process are required.

To effectively manage carbon emissions and mine waste it’s critical to develop a novel ex-situ MC technology pathway that allows efficient carbonation under close-to-ambient conditions without significant chemical inputs. With around 400 Mt of tailings generated globally per year that could be used to mineralise CO₂, ex-situ MC has been a recent focus across the mining and mineral sectors. This presents an opportunity to employ CSIRO’s cross-discipline expertise to develop novel electrochemical processes that significantly enhance and accelerate CO₂ mineralisation, and deliver a proprietary, breakthrough solution for integrated MC and waste management. This approach also results in new product streams including critical metals recovered from tailings and other mine waste, and production of green hydrogen and silica/carbonate materials, which provides the mining industry with extra incentives to adopt the technology.

Goal

Our research aims to develop technically feasible, efficient and cost-effective electrochemical approaches to enhance and accelerate ex-situ MC of mafic/ultramafic mine tailings.

We’ll develop the fundamental mechanisms and knowledge for electrochemical activation and leaching of ultramafic tailings, controlled formation of critical metal compounds, and efficient formation of mineral carbonates. Different types of electrochemical processes and cell configurations will be researched and tested to understand and optimise the process. Technology applications will be tested using targeted mine tailings or mineral waste (such as nickel and copper ore tailings and red mud) for electrochemical carbonation and critical metals recovery potential. In the final stage of the project, a prototype laboratory demonstration of the optimal electrochemical MC process is planned. The proposed electrochemical processes have inherent advantages in tailoring task-specific reactions at the electrodes such as boosted mineral dissolution at anodes and intensified CO₂ mineralisation of extracted metals at cathodes. They also enable efficient integration of tailings carbonation with mine waste processing, achieving permanent storage of CO₂ at scale, while reducing the mining industry’s environmental footprint and creating value-added products from mine waste.

Barriers

Using electrochemical processes is a fundamentally new solution for MC and requires significant research and development to advance it for practical applications.

The greatest challenge is likely to be the cost and energy consumption of these processes. We’ll mitigate this risk through design optimisation of electrochemical reactions and cell configurations to improve the simplicity and robustness of the system, its capability of critical metal recovery, and potential of electrical power reclamation. The key scientific challenges – enhanced and accelerated mineral leaching and dissolution via electrochemical process, boosted carbonation precipitation, and electrochemical cell figurations with low energy input and excellent robustness – will be addressed through a combined experimental and theoretical approach using the multidisciplinary capability and vast experience of our project team.

References

Rau, G. H., Carroll, S. A., Bourcier, W. L., Singleton, M. J., Smith, M. M., & Aines, R. D. (2013). Direct electrolytic dissolution of silicate minerals for air CO2 mitigation and carbon-negative H2 production. Proceedings of the National Academy of Sciences, 110(25), 10095-10100.