A research team discovers method to make standard separation methods faster and cleaner.
Rare earth elements are key components for numerous high-tech applications. However, before they can be processed, for example into magnets for wind turbines or electric vehicles, the 17 chemically very similar elements of the raw material group—divided into heavy and light representatives—must undergo an elaborate separation process. China has dominated this process for decades. To make their supply chains more independent, other countries are exploring new and sometimes more environmentally friendly separation methods.
One such approach has now been developed by researchers at the Oak Ridge National Laboratory (ORNL), which is part of the U.S. Department of Energy. Their study, conducted in collaboration with Vanderbilt University in Tennessee, could improve standard industrial separation processes.
To isolate a specific metal from solutions of rare earth minerals, ligands are used—chemical substances that selectively bind to individual elements in the solution. According to the ORNL report, the best current separation processes are done step by step, from heavy to light or vice versa. This process is time-consuming, costly, and generates a lot of waste, making it less environmentally friendly.
Ligand With Unique Properties Discovered
Through their investigations, the scientists reportedly discovered something unique: a ligand resembling the previously used compounds but behaves differently depending on experimental conditions. Depending on the solution’s acidity and the time involved, the ligand binds to different rare earths, both heavy and light. In typical separation systems, ligands are usually specific to just one of these subgroups, explains co-lead researcher Santa Jansone-Popova from ORNL.
The key insight is that the same compound could be used for multiple separation processes, reducing the necessary steps and making the entire method faster and cleaner. Additionally, the order of separation could be adjusted as needed.
Now that this phenomenon is known, further research could also discover more compounds with similar behavior, according to the ORNL. It is not the first time the facility has worked on rare earth elements. A team involving Jansone-Popova had previously licensed a separation process to an industrial chemical manufacturer.
More on new rare earth separation methods: Sandia National Laboratories has recently introduced a new separation method for rare earths using special molecules. Other approaches to rare earth separation involve bacteria, certain plants, and even sponges.
Photo: Ivan Samkov via Canva.
