Fluidized Bed Jet Mill CJM    

Fluidized Bed Jet Mill CJM


The CJM fluidized bed mill is a jet mill for the dry milling of the hardest materials up to a Mohs hardness of 10. Its grinding principle is based on the acceleration of particles in a gas jet by means of compressed air. After Acceleration the particles collide at high speed and are crushed. Characteristic for this grinding concept is the completely autogenous grinding of the product. The main advantages of this type of product-to-product grinding are the avoidance of contamination with other substances, gentle preparation and low wear thanks to the abrasion-free grinding.
Due to the integrated classifying rotor, powders with a steep grain distribution and a very low cut size of up to d97 2 µm can be produced.



• inorganic pigments

• technical ceramics

• Toner

• chemical products

• Food


Advantages for the operator:

• Milling of the hardest materials

• Contamination-free, abrasion-free milling

• Grinding of temperature-sensitive products

• Accurately defined particle size through integrated classifying rotor

• Lower compressor output due to use of flat nozzles



Fluidized Bed Jet Mill CJM






• different materials depending on application: (stainless steel, special steel, ceramics), surfaces treated or polished


• Internal coating - stainless steel, special steel, steel and polyurethane, steel and ceramics


• classifying rotor - various geometries


• different nozzle geometries - (flat nozzles, laval nozzles, cylinder nozzles)


• CIP cleaning



During expansion, the energy contained in the compressed gas in the form of heat and pressure is converted into kinetic energy. A natural limit for the outlet speed is the speed of sound. Through the use of Laval nozzles, the outlet speed can be increased beyond the speed of sound. Laval nozzles are characterized in that they widen divergently beyond the narrowest cross section.

The length of the divergent part of the nozzle is adjusted to the operating pressure. Frequently, compressed air of 20 ° C. and 6 bar is used as the grinding gas. This makes nozzle outlet speeds of approx. 500 m / s. By sucking in gas and material from outside the jet, the velocity of the gas jets decreases quickly after leaving the nozzles. The milling itself takes place by particle-particle collisions in the nozzle jets and in the focal point of the mutually directed jets.

The material to be ground enters the grinding container of the fluidised bed jet mill via a feed-in pipe, where it is fluidized by the air jets from nozzles directed towards one another. The particles entering the jets are accelerated and collide in the centrally located focus area of the jets. As a result, the particles of feed material are successively milled. Above the focus area an upwardly directed air flow forms, which transports the milled ground material to the classifiying rotor.
Which particle size is allowed through the classifying rotor can be adjusted by the parameters rotor RMP, airflow and gas pressure. The coarse material rejected by the viewing wheel, flows back into the fluidized material bed on the wall of the grinding container, where it is fed again to the grinding process. The fine material is transported pneumatically and subsequently separated by means of cyclone separators or bag filters.


Special Design Features


• modular design (jet module - classifier module)

• Foldable sifter module provides easy access for quick and easy cleaning and maintenance

• Sifter module with only one sifter wheel for uniform inflow

• exactly defined maximum particle size (finenesses of d97 <2 µm)

• No heating by grinding with cooled gas (20 ° C), thus suitable for temperature-sensitive materials

• automatic permanent lubrication of the bearing