Compressed air is most commonly used but steam is favoured for some applications and inert gases may offer advantages for particularly sensitive materials or materials with explosion risks.
The feed material is inspirated by a small proportion of the compressed gas through a venturi into the grinding chamber where numerous angled nozzles accelerate the material into particle-particle impact. There are no moving parts in the mill and no mechanical forces are applied to the grinding process.
The centrifugal movement of particles in the chamber provides effective classification to control product particle size. Products will typically be less than 10 microns. The mill is usually manufactured in stainless steel and can be supplied with various abrasion resistant linings. For pharmaceutical purposes it can be supplied within a full isolation system.
The particular advantages of this type of mill are:
- It produces a uniform particle size and shape
- It is very easy to clean and can be used for campaign grinding
- It can be used for hygienic or sterile applications
- It will process heat sensitive materials
- Materials can be blended during the grinding process
- Material can be coated with surfactants during the process