Abstract: The invention provides a cyclone unit for the removal of contaminants from flue gases by combination of a gaseous stream with an aqueous stream, comprising a housing defined by a cylindrical peripheral wall, by upper and lower extremities, and by a core element, the housing having a longitudinal axis and being provided with at least one inlet opening for receiving a gaseous stream and a plurality of inlet openings for receiving an aqueous stream thereinto, the cyclone unit further comprising at least one swirling means concentrically positioned and mounted within the housing coaxially with the longitudinal axis so as to provide a first annular space between an inner surface of the housing peripheral wall and the outer facing surfaces of the swirling means and to provide a second inner annular space between inwardly facing surfaces of the swirling means and the core element, the swirling means incorporating a plurality of slit-like elongated openings extending substantially tangentially with respect to the inn