Abstract: A cyclone separator (1) has an elongated vertical housing (2), whose upper section (3) is equipped with a carrier gas/product inlet (4), a separating wheel (6), and a carrier gas/fine product discharge (7). A lower section (9) of the housing defines an oversized product discharge (11). The housing (2) has a central axially extending built-in unit (12), which separates the cyclone carrier gas/particle flow stream, downwardly in a peripheral region, and upwardly in a central region. A lower built-in unit section (14) is joined to a cylindrical middle built-in unit section (15). An entry area of the middle section (15) is equipped with a constrictor (19) which with the built-in body forms a Venturi. Finally, a secondary air supply (24) enters into a lower inlet opening (9) of the lower built-in unit section (14) facing the constrictor (19). An injector effect is achieved which increases the suction, resulting in further improvement of the separating and sorting properties.