Fluidized Bed Grinding
Powders can be produced by injecting material into a fluidized bed There are the following fluidized bed arrangements:
1. Spray Dryer:
A liquid containing solid materials is sprayed into the hot material-laden gas flow. Particles develop in the gas flow by way of drying. The resulting particles are large with poor re-dispersing properties.
2. Fluidized Bed with Inert Beds:
A fluidized material bed is formed by the gas containing the prepowder injected from the bottom into a bed of inert particles.. However, only course particles can be produced because the impulse acting on the inert particles is determined only by the vertical up and down motion of the inert particles and is insufficient for forming fine particles.
3. Spray Towers with Fluidized Beds:
A gas with the prepowder is sprayed from a tower into a lower fluidized bed.
4. Fluidized Spouted Beds
In this system, a gas flow is supplied from the bottom to the spouted bed arrangement at a high speed to create a vertically rotating spouted bed. The liquid containing the solid is injected by nozzles into the rotating bed. The particle speed is ten times higher than the other methods. The solids are abraded and discharged in the form of dust. with particles sizes less the 50 microns and and collected with a dust collector.
Recent US Patents
11/2/2010
7,823,810
Method and device for the production and/or conditioning of powdered material
Rumpler et al of Glatt Ingenieurtechnik. Germany,have produced a dry, fine powder having a very small particle diameter is produced at a low cost in large quantities in a continuous operation. This is done by several stages in a fluidized spouted bed with inert particles. After each stage the smaller particles are separated by a jet chamber with an integrated dust collector. (RDC 2/21/2011)