Rare Earth Magnet Processing Equipment | Jet Mills for NdFeB & SmCo Powders

Rare Earth Magnets are the strongest type of permanent magnet. They contain elements that are in the Lanthanide series in the Periodic Table.  The most common type of Rare Earth Magnet is the Neodymium (Nd-Fe-B) magnet which has the strongest magnetic field and is the lower cost rare earth magnet option. The second most common type is the Samarium-Cobalt rare earth magnet, which has a higher cost, but has a higher Curie temperature, which allows them to be used in higher temperature applications. The higher strength of the rare earth magnets allows for smaller magnets which reduces the size of motors for mobile applications.

The demand for rare earth magnets is growing significantly with the growth of electrified power as the magnets are used for both electrical generation (wind generators) and electrical motors (including EV (cars, bikes, etc.), power tools and other electrical motors). They are also critical for industrial uses such as magnetic grates to capture magnetic impurities.

To produce rare earth magnets, ore from select areas are mined and they then goes through an extensive separation and purification process to concentrate the rare earths metal oxides. The oxides at the right proportion are mixed and metal alloys are formed through an induction furnace.

The alloyed metal is jet milled and the milled powder is sintered under a strong magnetic force to form the permanent magnet. Typically the magnet is covered with a coating such as nickel or stainless steel to protect the magnet from damage or oxidation.

Hosokawa Micron Group provides jet mill systems specifically designed for the milling of rare earth magnet material. We employ either the Hosokawa Alpine AFG fluidized bed jet mill or the Hosokawa Micron MJT target jet mill. The AFG jet mill uses a milling chamber with opposed jets at high pressure, so that the particles collide with each other at the center of the chamber (in a fluidized bed of material). The MJT jet mill uses a milling chamber with opposed jets at high pressure, with the jets and particles impacting a durable highly abrasion resistant ceramic/carbide target to mill the material. Both systems use Hosokawa’s high efficiency internal air classifier for sharp particle size control of the product. These systems are specially designed for the high flammability / explosive nature of this material, using inert gases and strict oxygen control throughout the system, including the compressed air, the milling and the product collection. Hosokawa has installed numerous systems that are used to produce high quality rare earth magnets.

Contact Hosokawa’s chemical / mineral applications department to learn more about rare earth processing and equipment.