The U.S. Department of Energy’s Ames Laboratory is working to more effectively remove the neodymium, a rare earth element, from the mix of other materials in a magnet. The initial results show the recycled material maintains the properties that made rare-earth magnets useful in the first use.
The potential is important because rare earth prices increased ten-fold between 2009 and 2011 and supplies, primarily in China, are in question due to quotas for China’s internal use.
This makes rare earth elements a recycling priority. So far the process hasn’t been especially useful, but the Ames Lab is showing the recycling process can be improved.
The newest Ames Lab research builds on decades of rare-earth processing experience. In the 1990s when rare earth prices were low, Ames Lab scientists developed a process that used molten magnesium to remove rare earths from neodymium-iron-boron magnet scrap. Back then the goal was to produce a mixture of magnesium and neodymium because the neodymium added important strength to the alloy, rather than separate out the high-purity rare earths.
Ryan Ott, the Ames Laboratory scientist leading the research gives some overview with, “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. It appears that the processing technique works well. It effectively removes rare earths from commercial magnets.”
Ott continues the narrative on the process, “We start with sintered, uncoated magnets that contain three rare earths: neodymium, praseodymium and dysprosium. Then we break up the magnets in an automated mortar and pestle until the pieces are 2-4 millimeters long.”
Next, the tiny magnet pieces go into a mesh screen box, which is placed in a stainless-steel crucible. Technicians then add chunks of solid magnesium. A radio frequency furnace heats the material. The magnesium begins to melt, while the magnet chunks remain solid.
“What happens then is that all three rare earths leave the magnetic material by diffusion and enter the molten magnesium,” said Ott. “The iron and boron that made up the original magnet are left behind.”
The molten magnesium and rare-earth mixture is cast into an ingot and cooled. Then they boil off the magnesium, leaving just the rare earth materials behind.
Ott continues, “We’ve found that the properties of the recycled rare earths compare very favorably to ones from unprocessed materials. We’re continuing to identify the ideal processing conditions.”
The next step is optimizing the extraction process. Then the team plans to demonstrate it on a larger scale.
“We want to help bridge the gap between the fundamental science and using this science in manufacturing,” said Ott. “And Ames Lab can process big enough amounts of material to show that our rare-earth recycling process works on a large scale.”
The idea is a superlative one. The rare earth elements are called rare because they are found in small amounts in very few places and other resources are difficult to reach. Research will reduce the amounts needed, but a future with electrification reaching further into more jobs is going to need the rare earths in greater supply.
This is important work well worth the attention and further funding.