Sustainable solutions for rare earth metal recovery

Researchers from Deakin University and Spain’s Tecnalia Research & Innovation have improved the process for recovering rare earth metals (REMs), which are essential for producing the components used in mobile phones and other technologies such as hybrid electric vehicles. The team’s research is published in The Journal of Physical Chemistry Letters.

Dr Cristina Pozo-Gonzalo, researcher at Deakin Institute for Frontier Materials and leader of the electromaterials project, said there was an urgent need to develop a cleaner and simpler process for recovering REMs, explaining that current extraction methods generate huge amounts of toxic and radioactive waste.

“After separating the metals from their end-of-life product, our team uses advanced electrolytes known as ionic liquids (liquid salt-based systems) to recover the rare earth metals from the resulting solution using a process of electrodeposition — when you use a low electric current to cause metals to reform and deposit on a desired surface.

“This new method for recovering REMs has great potential and minimises the generation of toxic and harmful waste. We are also aiming for a method that can easily be implemented widely across the world,” she said.

Dr Pozo-Gonzalo explained that increased demand for REMs — which include elements such as cerium, praseodymium, neodymium and lanthanum — was creating pressure on global supply chains.

“Consumption of REMs has been gradually increasing since the 1960s due to their use in electronics, optics and magnetics, making them ubiquitous in everyday applications such as television screens and computer systems. They’re also a key component of many modern technologies, including hard disk drives, clean technologies such as wind power turbines and batteries for hybrid electric vehicles.”

Dr Pozo-Gonzalo pointed to the unsustainable practice of sourcing raw rare metals. “Almost 85% of the world’s REM primary resources are in China, where their government has restricted exports for periods of time in the recent past, endangering availability and price stability,” she said.

“There’s growing concern that future access to these materials won’t be reliable, leading to them being targeted for reclamation and recycling. The primary extraction and processing methods for REMs are also energy-intensive processes that lead to the excessive generation of toxic and radioactive waste. We need a real alternative,” she urged.

Dr Pozo-Gonzalo said REMs were among the top critical raw materials identified by the European Commission, Geoscience Australia and the United States Department of Energy.

“The efficient recovery of REMs from recycled materials is becoming increasingly important, given that only about 3–7% of REMs are currently recovered from end products because of technological difficulties,” she said.

“Our work addresses a key knowledge gap in the REM recycling process and is an important early step towards establishing a clean and sustainable processing route for REMs and alleviating the current pressures on these critical elements.”

The project is a collaboration between Deakin IFM researchers Dr Cristina Pozo-Gonzalo, Professor Maria Forsyth, Associate Professor Jennifer Pringle and Dr Matthias Hilder; and Tecnalia Research & Innovation researchers Laura Sanchez-Cupido, Amal Siriwardana and Ainhoa Unzurrunzaga.

Image caption: Dr Cristina Pozo-Gonzalo supervising a PhD researcher. Image credit: © Deakin University