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
feeding station
dosing system
Alpine AFG-R jet mill
cyclone NAZ
sampler
target product
dust collector
ultrafine dust particles
pressure tank
compressor
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.
AFG Fluidised Bed Opposed Jet Mill
The AFG fluidised bed opposed jet mill is used in various process steps during battery manufacturing. It is used for the production of powders with a steep particle size distribution and sharp top size limitation in the range < 5 µm to 200 µm.
Applications
- Grinding of lithium and lithium compounds
- Grinding of silicon and silicon compounds
- Grinding of rare earths (with highly flammable properties)
- Delamination: separation of cathode material from aluminium foil or anode material from copper foil
Principle of operation
Jet mills are impact mills which are used to achieve maximum fineness values at maximum product purity. Such particle sizes can only be achieved in connection with an air classification process step . Fluidised bed opposed jet mills are equipped with a dynamic deflector-wheel classifier.
In a fluidised bed opposed jet mill, the product is fed via a feed lock. A product fluidised bed then forms in the grinding chamber, which is fluidised by the gas jets. From there, the particles enter the gas jets and are accelerated. They collide with each other again and again and are thus comminuted. A classifier wheel rejects those particles that are still too large and conveys them back into the fluidised bed. The particles that are fine enough are separated from the grinding gas by a separator or dust filter.
The fineness of the product is adjusted via the speed of the classifier wheel. All-important is a high product loading of the nozzle jets in order to obtain a high particle concentration and thus high impact probabilities. The unique Megajet nozzles were specifically developed for this purpose. The product level in the machine is controlled by load cells or by monitoring the current loading of the classifier drive.
Your advantages with the AFG fluidised bed opposed jet mill
Production of active cathode and anode materials
- Wear protection with different ceramics (standard for grinding lithium, optional for grinding silicon and rare earths) : no contamination of the product. In addition, the effort for maintenance and service is reduced and thus also the downtimes.
- Easy accessibility for easy cleaning and maintenance
- High throughputs with low pressures: energy-efficient production of fine powders with little energy
- Design for contamination-free processing
- Gas- and dust-proof design protects staff and the work environment from toxic lithium compounds and protects the materials from exposure to moisture
- Integrated classifying wheel(s) arranged horizontally in the classifier top section. The results are a steep particle distribution and an exact top cut. These are necessary for optimum coating thicknesses for electrodes.
- When processing silicon and silicon compounds, the system can be run with nitrogen or argon. This reduces costs. Due to the lack of oxygen, the silicon cannot oxidize. This makes it more active and requires less space in the anode. It also makes it possible to process rare earths.
Direct recycling of production scrap
- High degree of separation prevents loss of valuable raw materials. The cathode or anode material is very pure and contains no traces of aluminium or copper foil.
- Separation from the foil takes place in the cyclone: no additional classifying necessary
- Gas- and dust-proof design protects the materials from moisture
- If the system has to be operated with nitrogen it can be run in a closed loop. This keeps the loss of nitrogen low and reduces costs.
Filling & Weighing Systems
Filling and weighing are important process steps in the production of lithium-ion batteries. Our accurate weight-controlled filling systems maintain the highest standards of hygiene, dust control and product integrity. They deliver accurate, stable and repeatable weight readings and can be designed for use in hazardous areas. They incorporate interchangeable, Stott design inflatable packing heads and integrated weigh platforms to provide automatic control of bulk and dribble filling modes.
Applications
- Filling and weighing various raw and active materials in the production of lithium-ion batteries
Your advantages with our filling and weighing systems
- Our contained filling and weighing system is easy to operate and guarantees a high level of product integrity
- Designed for flexible filling of a range of containers of various sizes including drums with or without liners, IBC’s, FIBC’s, Polybottles, high containment flexible bags
- A single, easy to read, flush mounted control panel display, including continuous weight readout and other process parameters. The system can be connected to the customer’s distributed control system (DCS).
- Compact inward seal that does not come into contact with the product, or alternatively the fill weigh systems can be designed with outward inflatable seal or downward inflatable seal to suite the application.
- A range of dosing devices are available to achieve weighing accuracy during filling, ranging from simple butterfly valves to highly accurate screw feeders depending on material characteristics and accuracies required.
- Secondary containment is provided by enclosing the fill / weigh system inside one of Hosokawa’s Horizontal Laminar Flow Booths designed for the application or alternatively the filling system can be integrated into a Hosokawa Downflow booth or Hosokawa Glovebox/Isolator system.
- All of our systems are available in bespoke designs suitable to meet customers’ requirements for the application.
