Pneumatic classifying procedure and means

Abstract

The invention concerns a pneumatic classifying procedure and apparatus for dividing particulate material into a fine product consisting of lighter particles and a coarse product consisting of heavier particles. The classification takes place in a cylindrical classifying space (1) in which can be established a centrifugal field with the aid of tangential supply of the material to be classified or with the aid of a mechanical rotor, the field separating the fine product into the center of the classifying space and the coarse product to its outer margin. It is essential in the invention that the coarse product is removed with the aid of a separate gas flow which is tangential to the centrifugal field. The gas flow runs in a passage (11) which is tangential to the classifying space (1) at the site of the coarse product removal aperture (9). When the coarse product has been separated from the gas flow, the gas may be returned to the process to serve as fluid in the centrifugal classification taking place in the classifying space (1) of the process.

Dependencies are inferred from the claim text.