Rare earth elements (REE) are key components in almost every electronic gadget that people own these days. What is more, these chemical miracles are found within all electric and hybrid vehicles, as part of the battery, the traction motor and the regenerative breaking system. REEs, or more specifically REE magnets, are essential components in gearless generators used in all wind turbines. Other uses of these elements include LED bulbs, hard drives, CD-ROMs, DVDs, plasma and LCD displays, and they cover a wide range of applications in the medical industry.
Mining these elements is extremely polluting and highly expensive business, mainly because they cannot be found in the form of ore deposits due to their geochemical properties, and it is very rare to find large, economically exploitable, amounts at one location. What is more, China is currently the main world’s supplier, determining and heavily controlling the global market.
Considering how much use and how high the demand for these elements is, it is a little surprising that so little is done on recycling and reusing them. Most industries rely on freshly mined supplies, and they actually need quite a lot of them- just a few examples, a single MRI machine uses about 700kg of these elements in the form of magnets, while a typical hybrid vehicle contains about 28 kg of REEs.
Now, a main reason behind the limited recycling practice is the fact that each application requires different quantities of REEs in different ratios. Once these are mixed, it is very difficult and pricey to get them unmixed again. This is especially the case with neodymium and dysprosium, two REEs, which are often mixed in different concentrations to create super magnets with brilliant thermal properties.
This is the challenge that a team from the University of Pennsylvania decided to take on in a study funded by the Early Career Research Program of the U.S. Department of Energy’s Office of Science and the Research Corporation for Science Advancement. Instead of focusing on looking for alternative mining techniques, the guys put their efforts towards finding ways to effectively separate the elements from each other and make them reusable again.
The researchers first turned the magents into powder, and then used a specialized ligand (an ion or molecule), which binds to neodymium. Once all of this element is extracted, they used a weak acid to remove the ligand, so that both REEs can be ready to go again. Detailed description of the method can be found in the article published in the journal Angewandte Chemie, International Edition.
According to the lead author Eric Schelter, this process could take no longer than 5 minutes, if the right ligand is used. This chemical technology is much faster, cheaper, and much more eco-friendly than the liquid-liquid extraction method that is used for mining the element.
The method has huge potential, especially if it is also modified and adjusted to recycle REEs from LED bulbs. Recycling and reusing should always be the preferred mean for supplying of any type of material, especially if the alternative is mining, so fingers crossed this technique becomes widely used very very soon.
Image (c) Penn