Abstract: The invention relates to a process and apparatus for the separation of heavier from lighter fractions in aqueous slurries by means of centrifugal force. A slurry is made to spin in a separation chamber under influence of differential pressure. The differential pressure, which can amount to several bars, is generated by means of a pressure increasing stage in the form of a transport rotor device (20) which acts in conjunction with a stator arrangement (22). This pressure boosting stage takes place immediately upstream of an inlet of the slurry into the separation chamber (4). Rotor blades of a cyclone rotor device (10) and rotor blades of the transport rotor device (20) can be mounted on the same rotary shaft (5). The separation of floatable fractions in aqueous slurries can be enhanced by presence of micro gas bubbles introduced into the separation chamber (4).