United States – High-purity rare earths like neodymium commanded low prices in the 1990s and so were initially incorporated into rare earth magnets. But with their value witnessing a ten-fold increase between 2009 and 2011, scientists at the US Department of Energy’s Ames Laboratory are working to more effectively separate these elements from the magnets’ other ingredients.
‘The goal is to make new magnet alloys from recycled rare earths,’ states project leader Ryan Ott. ‘And we want those new alloys to be similar to alloys made from unprocessed rare earth materials.’ The team’s technique has proved successful in removing rare earths from commercial magnets, with results to date indicating that the recycled materials maintain the properties that make rare earth magnets useful.
The project started with ‘sintered, uncoated magnets’ that contain three rare earths: neodymium, praseodymium and dysprosium. ‘We break up the magnets in an automated mortar and pestle until the pieces are 2-4 mm long,’ the scientist explains. Next, the pieces are placed in a stainless steel crucible and subjected to ‘chunks of solid magnesium’.
A radio frequency furnace heats the material and the magnesium begins to melt, leaving the magnets themselves behind in solid form. ‘What happens then is that all three rare earths leave the magnetic material by diffusion and enter the molten magnesium,’ says Mr Ott. He adds that his team will ‘continue to identify the ideal processing conditions’.
With the focus now on optimising the extraction process, the Ames scientists aim to demonstrate their progress on a larger scale in the months to come.
For more information, visit: www.ameslab.gov