Advanced rare earths for high-performance electric motors

Neodymium-iron-boron (NdFeB) or Samarium-Cobalt (SmCo) alloys are used to manufacture magnets, which are an essential component in electric motors. This means that alongside graphite and lithium, rare earths are important energy performance materials in electromobility, aviation and wind turbines and therefore link the rare earth elements industry to the energy transition. 

In addition to electric motors for electric vehicles, household appliances and industrial machinery, the magnets are also used in other applications: in electronics (including loudspeakers, sensors and hard drives) and in imaging devices in medical technology. The largest deposits of rare earths are found in China, although rare earths have also been discovered in Australia, Greenland, the USA and Russia. As the performance of the magnets depends crucially on the quality of the ingredients, the processing of the rare earths plays an important role here. For this, the Hosokawa Micron Group has developed the ideal process. 

Challenges in the processing of rare earths for high-quality sintered magnets

The special properties of NdFeB pose a number of challenges for magnet production. The main problem is that neodymium is pyrophoric: very fine particles start to oxidise on their own when they come into contact with oxygen. At the same time, however, a steep particle size distribution is required (d50 < 3-5 µm). For this reason, a system for processing neodymium must be operated gas-tight and run with inert gas (nitrogen or argon). An integrated passivation process is also necessary: if the system needs to be opened (e.g. for cleaning or maintenance), it must be passivated, i.e. filled with air in a controlled manner. This allows the smallest particles to oxidise in a controlled manner without causing any harm. 

While NdFeB magnets are frequently used, SmCo magnets are less common in comparison. Nevertheless, SmCo magnets offer advantages such as heat resistance up to 350 °C and do not require additional corrosion protection. 

Jet milling of rare earths for e-mobility

The AFG-R fluidised bed opposed jet mill is used especially for processing neodymium-iron-boron alloys and has become a reference in the world of high-quality magnet production. This version of the AFG jet mill has a bottom nozzle so that even particles that are difficult to grind can be ground. Thanks to ultra-fine particles with a fineness of d50 < 3-5 µm, super-strong magnets can be produced. This is due to the fact that with increasing steepness of the particle size distribution in the range of d50 < 3 - 5 µm, the remanence (Br) and the coercive field strength (Hc) in the final magnet increase. The mill can be operated gas-tight with inert gas (nitrogen or argon). The jet mill is available on a laboratory scale - a scale-up to a production plant with throughputs of up to 250 kg/h is possible. This also makes it the ideal solution for research and development.  

A cyclone is installed downstream of the AFG-R fluidised bed opposed jet mill to collect the product. The ultrafine dust is separated in the downstream filter. The nitrogen is generated by a two-stage screw-type compressor which – in contrast to other compressor types – operates in a completely oil-free manner. Contamination of the end product is thus ruled out. Together with the steep particle size distribution, this guarantees maximum product quality. 

You can rely on over 40 years of experience with pyrophoric rare earths and over 50 installed systems worldwide! 

AFG-R fluidized bed opposed jet mill: the perfect machine for enhancing rare earths

The AFG-R jet mill brings a whole range of benefits to your rare earth processing: 

  • Very steep particle size distribution (d50 < 3 – 5µm) for a better sintering process 
  • Consistent product quality maintained by automated processes, ensuring a constant and steep particle size distribution  
  • Homogeneous grinding for stronger magnetic properties 
  • Extremely low content in the problematic submicron range 
  • Circulating gas reduces nitrogen consumption and lowers operating costs 
  • Minimized product waste with advanced cyclone technology 
  • Oil-free screw-type compressor rules out the possibility of oil contamination 
  • Sampler under the cyclone for testing the product quality 
  • High throughputs possible (up to 250 kg/h) 
  • Safe system operation 
  • Low material loss 
  • Complete turnkey solutions 
  • Available for R&D in lab-scale 
Rare Earths system

feeding station

dosing system

Alpine AFG-R jet mill

cyclone NAZ


target product

dust collector

ultrafine dust particles

pressure tank


Trials in our test centre: Let’s find the perfect solution!

Would you like to find the ideal solution for processing your rare earth materials? We would be happy to carry out trials with your materials in our test centre in Augsburg/Germany. Together we will find the ideal solution for your process. 

Thanks to a co-operation with a renowned institute, we can also produce magnets for you using your finished powder. 

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