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Ames Lab researchers remove and reuse rare earth metals from magnets

With rare earth metals being a vital but costly component of many next-generation technologies, ways to stretch the availability of the existing supply – such as recycling – could be important in keeping costs down.

Rare earth metals, of which China has a lot, are difficult to extract and demand is growing faster than supply. This is leading to price increases and fears of shortage.

China itself has placed restrictions on exports of their supply, saying this is will regulate the environmental effects of the extraction process. Still, this has become a global concern.

Rare earth recycling could help stretch the world’s supplies. Scientists at the U.S. Department of Energy’s Ames Laboratory have successfully removed neodymium from the mix of other materials in a magnet. Initial results show that the recycled materials still maintain their important properties.

The new work builds on a process that Ames Lab scientists developed in the 1990’s. Back then, they used molten magnesium to remove rare earths from neodymium-iron-boron magnet scraps.

“Now the goal is to make new magnet alloys from recycled rare earths. And we want those new alloys to be similar to alloys made from unprocessed rare-earth materials,” said Ryan Ott, the Ames Laboratory scientist leading the research.

The researchers take magnets that contain three rare earths – neodymium, praseodymium and dysprosium – and break the magnets up into pieces around 2 millimeters to 4 millimeters long. The magnet pieces are placed in a mesh screen box in a stainless-steel crucible. Solid chunks of magnesium are added to the mixture.

A radio frequency furnace heats the material causing the magnesium to melt while leaving the magnet chunks intact.

“What happens then is that all three rare earths leave the magnetic material by diffusion and enter the molten magnesium,” said Mr. Ott.

The molten magnesium and rare earth mixture is then cast into an ingot and cooled. Then they boil off the magnesium and the rare earth materials are left behind.

“We’ve found that the properties of the recycled rare earths compare very favorably to ones from unprocessed materials,” said Mr. Ott. “We’re continuing to identify the ideal processing conditions.”

After optimizing the extraction process, the team plans to demonstrate it on a larger scale.

Aside from Mr. Ott, Ames Laboratory scientist Larry Jones worked on the project. It was funded through a work for others agreement with the Korean Institute of Industrial Technology. – EcoSeed Staff

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