A device for the cyclonic separation of solid particles contained in a fluid, comprising a primary cyclone chamber, a secondary cyclone chamber, an inlet channel for fluid loaded with solid particles opening into the primary cyclone chamber, an outlet channel for fluid cleaned of the solid particles connected to the secondary cyclone chamber, and a ducting unit connecting the primary cyclone chamber to the secondary cyclone chamber and surrounded by the primary cyclone chamber. The ducting unit comprises a core delimiting the secondary cyclone chamber and having at least one helical groove having a bottom which diverges away from an axis of the secondary cyclone chamber in a direction towards the latter, and a cap covering a part of the core in such a way as to delimit, with the groove, a channel connecting the primary cyclone chamber to the secondary cyclone chamber.