Chemical engineer Nelson Brito calls. “It begins! I see the first cracks.” His colleague Carlo Burkhardt immediately rushes over. They stand in front of a fume hood, filled with pots, hoses, tubes, meters. At eye level is a small, square sealed compartment, part steel, part thick glass. There is a small magnet in it, about 2 by 4 centimeters. “Look. Over there. Top left corner,” points out Brito, referring to the cracks that have appeared in the magnet.
Burkhardt is scientific director of the Institute for Strategic Technology- und Edelmetalle at the Hochschule Pforzheim. He coordinates the European project Susmagpro, in which scientists are looking for ways to recycle a commonly used type of magnet, the so-called neodymium-iron-boron magnet. The test set-up we are facing is the most tangible result to date. Brito has just opened the tap with the supply of hydrogen gas. “The gas disintegrates and crushes the magnet within a few minutes,” says Brito.
This is an important project for Europe. More than half of all magnets produced each year contain rare earth metals, such as neodymium. Growing quantities of this will be needed in the future for use in electric cars and wind turbines. China dominates and controls the rare earth market. The European Commission wants to become more independent and has placed the rare earth metals on the ‘list of critical raw materials’ in 2011 – the supply of these substances is estimated as vulnerable. Since then, she has subsidized research to increase self-sufficiency through more own extraction and recycling. Magnets now end up on the scrap heap. Europe recycles less than 1 percent of its magnetic waste.
Magnets are bigger in some hybrid motors than others
The project that Burkhardt is coordinating has been awarded 13 million euros from the Brussels research program Horizon2020. 18 other universities (including Leiden University) and companies are participating. They try to find answers to questions like: how do you remove a magnet from a computer hard disk drive, from a hybrid or electric car engine, or a speaker box? And how do you then extract the rare earths from that?
“On laptops and computers,” Burkhardt says, “we first tried to manually remove the magnet from the hard disk drive. That was not a thing to do.” A robot has now been built that uses a magnetic sensor to determine in which corner of the hard disk drive the magnet is located, and then breaks that corner off. Other devices are still looking for a solution. Burkhardt: “In the traction motor of hybrid cars, magnets are often placed next to each other in several stacks. We tried to push it out. But that does not work.”
Shaver or TV
Another problem Burkhardt and his colleagues have encountered is the varying attachment and composition of magnets. They are glued in different ways, they have different coatings. And in one hybrid engine the magnets are bigger than in the other. That makes removing the uniform difficult.
Burkhardt’s group has set up a database in which all kinds of data are stored per magnet. With a DMC code printed on the magnet (data matrix code), these data can then be easily retrieved. “But it is more convenient to introduce standards,” says Burkhardt. They would then prescribe how a magnet should be attached to a shaver, a loudspeaker box or a TV, and how such a magnet is composed.
Photos Hochschule Pforzheim
Once a magnet is insulated, it can be recycled. Burkhardt’s group uses a technique developed and patented by the University of Birmingham – also a participant in the project. In this case, hydrogen gas is added to the magnet.
Burkhardt explains how it works. A magnet is made up of countless small magnets, in English grains called, granules. They are 20 to 50 micrometers in size (a micrometer is one thousandth of a millimeter). The grains are connected to each other via a boundary layer rich in the rare earth metal neodymium. Hydrogen gas reacts with that neodymium, with the result that the granules lose their cohesion. The magnet shatters.
Melting into grains
To make a complete magnet again, you treat the grit in the same way as ‘fresh’ material, says Burkhardt. “But you can skip the first step in the normal process. That saves a lot of energy.” In that step, neodymium, iron and boron are combined and melted into granules at temperatures up to 1,300 degrees Celsius. Then the granules are compressed and magnetized so that they exert their magnetic force in the same direction. Finally, there is the sintering. At a temperature just below the melting point of the grains, the boundary layer between the grains grows and this strengthens their bond.
Burkhardt also points out that the quality of magnets decreases somewhat over the years, because oxygen from the air reacts with the boundary layer. If a recycled magnet is only made up of grit from older magnets, it will have the same quality as the older magnets. But the group is also investigating whether you can add fresh neodymium to it and whether the quality of the recycled magnet improves.
Now they can produce 2 kilos of magnetic grit per hour. That will soon go to 500 kilos
The project has since resulted in two spin-offs that are trying to commercialize the recycling of neodymium-iron-boron magnets, in Pforzheim and Birmingham. The fact that two small companies have been set up, and not one, has to do with Brexit, says Burkhardt. “It has made it much more difficult to transport material, such as magnetic waste, back and forth.”
The project that Burkhardt is leading will end in November next year. But last June the European Commission already made 12 million euros available for a follow-up project. That’s a good thing, says Burkhardt, because they have just started scaling up the recycling process. Now they can produce 2 kilos of magnetic grit per hour. That will soon be 500 kilos. Space has already been made available in the building for scaling up. We walk towards it via some stairs and corridors. There are crates full of different magnets from loudspeaker boxes, hard disk drives, hybrid motors. “I expect the kilns for sintering to be delivered within a few weeks.”
movable factory
In addition, the project is working on building the entire recycling process in a container. “A portable factory,” says Burkhardt. In doing so, he believes, they are responding, among other things, to the obligation that Europe places on ‘server farms’. They have to recycle old servers on site.
A few years ago, Brussels had set itself the goal that by 2030 about 20 percent of the European demand for magnets would be met through recycling. But that percentage will certainly not be achieved, says Burkhardt. Recycling is still in its infancy, and the demand for magnets has grown much faster than expected. “I don’t like that percentage anymore.”
Back in the lab with the test set up, Brito puts his arms through the two black rubber tubes sticking out of the closed fume hood. He gently grabs the compartment containing the magnet and shakes it gently from side to side. “To speed up the process a bit.”