Report on a conference sponsored by the NATO Science Committee

A fluid energy mill having an inlet chamber, a classification chamber, and an upstack and downstack connecting opposite ends of the inlet chamber to the classification chamber. The inlet chamber, which is positioned angularly to the upstack and downstack, has a Venturi portion between the upstack and downstack. A feed inlet is also positioned angularly to the upstack as well as to the inlet chamber. This feed inlet also has a Venturi portion. A feed hopper is provided above the feed inlet and is in connection therewith. A pressure fluid nozzle is provided below the hopper to project the fluid and particles from the hopper through the Venturi in the feed inlet. A similar but opposed nozzle is provided below the downstack to project fluid through the Venturi in the inlet chamber toward the upstack. The fluid and particles propelled by each nozzle meet and impact below the upstack and the resultant fluid and particles pass upwardly through the upstack and centrifugally move through the mill where the lighter particles are centrifugally separated from the heavier particles and exhausted from the mill.