Materials to feed the green energy revolution

Dr Kathryn Mumford is an Associate Professor in the Department of Chemical Engineering at the University of Melbourne, specialising in separation processes in ion exchange, solvent absorption and solvent extraction technologies. In collaboration with industry, her recent research has pioneered a more efficient, greener process to produce lithium carbonate.

Dr Mumford leads the Sustainable Resources platform, which focuses on research to support the transition to green energy, reduce environmental impact and develop smart mining and processing. Here, she discusses how the platform is tackling the industry’s greatest challenges, and the role the sector will play in decarbonising the world.

I’ve been thinking about sustainability and environmental health throughout my whole career. I saw the consequence of waste and was compelled to develop ways to reduce its impact. My PhD was around environmental clean-up, specifically cleaning up tip sites and fuel spills at contaminated sites in Antarctica – I’ve since been back to Antarctica seven times on clean-up missions.

After my PhD I went and worked for industry. I worked at Worley Parsons in Canada, which helped me to understand how industry operates, what the different priorities are and how different organisations and people work. Once I returned home, my focus was around carbon dioxide separation from flue gas emitted from large power stations, and then the use of solvent extraction in minerals and pharmaceutical processing.

Resources are being used more heavily - we're extracting more and more from the earth. Developing processes that can extract materials sustainably, in a cost-effective way, and purified is going to be an increasing challenge, especially when it comes to rare earths.

Our projects are seeking to solve these global challenges. We have programs around dewatering tailings, novel flotation techniques, and new solvent extraction systems to target different sources of metals. We’re also looking at battery recycling processes. We've got this new revolution around lithium-ion batteries, but there's no clear technological solution on how to best recycle those batteries. Our lithium project focuses on the extraction of lithium from brine solutions in South America. Normally lithium is extracted through a precipitation process that results in a low yield and low purity product that requires a large amount of water and massive evaporation ponds. We've developed a solvent extraction process that doesn't need large dams – a once-through solvent extraction process where everything's finished within the day.

The industry’s new drivers are going to be around effective separation of rare earth minerals, which are really important for electronics. They’re really high value metals, but found at extremely low concentrations. The challenge is finding solvents and membranes that can effectively separate something that is at that low of a concentration and make a high purity product. Rare earths are often present in tailing ponds left over from the extraction of copper, nickel and cobalt – so rather than the tailing ponds being a waste, there is opportunity to re-extract it for these rare earth materials.

It is imperative that, in extracting the materials needed for the batteries that will support green energy, we don’t end up causing more environmental damage.

Working towards decarbonisation, our priority is to develop technologies that are not only sustainable, but also cost-effective. Batteries are the technology that will help us maintain energy stability whilst also reducing carbon dioxide emissions from vehicles. But we must remove cost barriers to transitioning to battery-powered energy and transport systems. If you've got a cheaper, efficient, and more competitive solution, that’s always going to be more successful.

Collaboration is imperative to the Sustainable Resources platform. Without partner organisations or other universities to work with, we don’t get the full scope of problems facing the resources industry. Our first step is often just talking to people and understanding their processes, and then we can brainstorm and develop new solutions. Staying up to date makes the work more interesting – the exciting part of being at a university is having the freedom to problem-solve.