Choice of the classifier type is dictated by product requirements,
technological and economic factors. Rational
design and improving separation quality is done by creating
a well-defined and stable air flow, reducing turbulence, eliminating
particles collisions, controlling feed and repeated
cleaning of both fractions. Among gravitational type classifiers,
fluidized-bed based devices provide stable operation
and sharp separation in the cut size range of 50–1000 m.
Smaller-size particles may be separated by rotor classifiers,
enabling easy cut-size control and providing products’ recoveries
up to 80%.