Although magnets for electric motors are produced under costly and environmentally unfriendly conditions, scrap magnets have hardly been recycled and reused so far. Scientists have now developed a new recycling method that allows new magnets to be made from old magnets without significant loss of efficiency. A process that can be implemented on a large scale and that can be varied according to requirements could promote the use of such recycling magnets in e-mobility.
The development of electromobility is an important step in the energy transformation and should contribute to the reduction of CO2 emissions in the long term. According to the plans of the federal government, seven to ten million electric vehicles are to be registered by 2030. However, it also means that more and more electric motors and high-performance permanent magnets are needed for their operation. They account for about half the cost of an engine and include rare earth metals such as neodymium or dysprosium, among others. The extraction of these rare earths takes place mainly in China and releases, among other things, toxic by-products that pollute the groundwater and thus harm people and nature.
Is it a magnet or can it go away?
But although magnets are produced under such costly and environmentally damaging conditions, so far no sustainable recycling processes exist. Instead, used magnets usually end up in a scrap yard and are fused there with other scrap metal. Konrad Opelt, a material scientist and his team from the Institute of Material Cycles and Resource Strategies Fraunhofer in Hanau want to change that. To prove that electric motors with old recycled magnets can achieve the same performance as new magnets, scientists first created an e-bike, e-scooter and hoverboard.
“For all new vehicles, we first characterized the engine in detail to obtain the appropriate parameters, with which we can later compare the performance of the recycled magnet motors,” reports Opelt. They have received old magnets for the recycling process from different industrial partners, meaning that they vary greatly in performance, shape and quality – Opelt and his team want to stay as close to reality as possible and show that the recycling process can also work with very different starting materials.
From old to new
When recycling old magnets, their material is crushed and exposed to a hydrogen atmosphere. The hydrogen permeates the material to break up into granules which are then pulverized by the jet mill. This powder can then be put into a mold and “baked” in a new magnet. The decisive advantage: While the starting material has to be melted in the production of new magnets that consume a lot of energy, this is no longer necessary with old magnets. Chopping is enough. “We can easily skip environmentally harmful raw material extraction and energy-intensive melting,” explains Opelt.
In theory, thousands of magnets can be processed simultaneously in this recycling process. However, it is difficult to prevent the magnets from contacting some oxygen, which slightly reduces performance. “But we can counter this in a targeted way, for example by adding ten to twenty percent of new material or by further processing the microstructure of the magnets,” says Opelt. The performance of the magnets can then be determined on the finished end product or even in the powder stage. Scientists are still working on further optimizing the treatment process during the recycling process. Konrad Opelt, however, is confident that they will soon be able to install recycled magnets in electric motors.
Recycling becomes individual
In the future, scientists also want to enable application-specific recycling options by deriving a property portfolio from analyzes of recycled magnets. This should help future users to adapt the recycling processes to their needs in such a way that specific magnetic properties can be achieved depending on the composition of the material. If scrap recycling were indeed widely used, it would be a key step in building a value chain that is not only sustainable but also makes e-mobility less resource dependent. Opelt hopes that in the future, manufacturers will make sure that the magnets are easy to remove and reinstall during the production of electric motors, thus allowing recycling.
Source: Fraunhofer Institute for Material Cycle and Resource Strategies IWKS