A Rare Earth Solution

With the proliferation of electronic devices comes a responsibility to the environment and an appreciation for future industrial materials challenges. At WPI, the focus on extracting valuable materials for reuse and recycling is cutting edge.

It’s not surprising that metals recovery and recycling are sensitive to regulations and fluctuating market prices, meaning manufacturers typically balance their costs and bottom lines with sustainability or environmental benefits. So Center for Resource Recovery and Recycling (CR3) researchers are also working on projects to make recovery processes cheaper and easier than mining, which is the case with their work on rare earth metals.

Smartphones, hybrid-electric cars, solar panels, and wind turbines all use various rare earths, a class of 17 elements, including neodymium and dysprosium, that, for example, enable touch screens to function. Rare earths aren’t necessarily rare, but most of those used by manufacturers worldwide are mined in China, giving that country a near monopoly on supplies. When China began slowing produc­tion several years ago and prices spiked, industries began paying more attention to recycling rare earths.

As a result, General Motors, which like other vehicle manufacturers faces tougher recovery and efficiency regu­lations in the next decade, joined CR3 to support research for rare earth recovery from magnets within vehicle drive units — the motors in electric and hybrid cars. But shredding motors was considered a low-efficiency and thus prohibi­tively expensive process.

Marion Emmert, PhD, assistant professor of chemistry and biochemistry, worked with GM to alter those views. “We weren’t discouraged by this mantra that you cannot shred motors with high recovery efficiency,” she says.

Emmert developed a three-step solution, taking inspi­ration from “green chemistry” and a little bit of home economics. Her process starts with baking the motors at 450o C in an oven for an hour. That weakens the magnetic strength of motor components so they can be run through an industrial shredder. Then the researchers apply a chem­ical solution that selectively dissolves the remaining smaller bits of magnet, filtering off the steel and copper, and leaving behind a dark solution of rare earths, iron, and boron. Finally, Emmert’s team introduces an acid that extracts a rare-earth powder that can then be reused in a new generation of magnets.

Emmert developed a three-step solution, taking inspi­ration from “green chemistry” and a little bit of home economics.

The process taps existing technologies but integrates them in a new way on auto motors with complex material mixtures. “The technological breakthrough is that we’ve shown that we can selectively attack and remove the magnets from these materials mixtures,” Emmert says, adding that her group has filed for a patent and is talking to companies about commercialization. Eventually, the process could also be applied to cell phones and other electronics.

“With rare earth recovery, there’s huge interest out there because people are aware of the sustainability issues,” Emmert says. “One of the things that is really exciting to me is that I feel we are making a difference with our research. We’re providing guidelines on how to better recycle, and we’re providing ideas that other people with different back­grounds don’t have.”