Device for generating gas bubbles in suspensions, which are contained in a tank , having a rotation-symmetric stator and a rotation-symmetric rotor , which is connected to a hollow drive shaft , wherein the stator , the rotor and the hollow drive shaft are arranged concentrically about a vertical axis of rotation of the rotor and the drive shaft , and the rotor executes a rotational movement about the axis of rotation inside the stator , wherein • the rotor has, on its upper end, a plate , which is oriented perpendicular to the axis of rotation and on which vanes are arranged that are oriented perpendicular to this plate and radially to the axis of rotation , wherein the radial extension of the vanes is greatest in the region of the plate , • the stator is constructed as a cylindrical hollow body and the latter projects axially beyond the rotor on its upper side, wherein the casing of the cylindrical hollow body consists of a plurality of strip-shaped, radially oriented baffles and is arranged on a support device, • the support device has a bottom surface , a spacer and a vortex breaker , • the stator is spaced from the bottom surface by the spacer of the vortex breaker , • the top surface, opposite the bottom surface, of the stator has an opening, which is constructed in such a manner that the rotor can be passed through it and the opening is surrounded by a cover ring , which seals the baffles in an axial direction, • at least one opening for the intake of air into the suspension is arranged on the hollow drive shaft of the rotor , below the plate of the rotor , in the region of the vanes , characterized in that • the rotor has vanes , which extend from the plate in an axial direction to varying distances, • at least two vanes of the rotor , which are arranged in the circumferential direction of the drive shaft , have a radial distance r to the axis of rotation , a first portion of the baffles of the stator runs at an angle α of 30° to 60°to the axis of rotation and a second portion of the baffles of the stator runs at an angle α' of -30° to -60° to the axis of rotation and the angles α and α' have the same value, and • the baffles of the stator are connected to each other. • the rotor has, on its upper end, a plate , which is oriented perpendicular to the axis of rotation and on which vanes are arranged that are oriented perpendicular to this plate and radially to the axis of rotation , wherein the radial extension of the vanes is greatest in the region of the plate , • the stator is constructed as a cylindrical hollow body and the latter projects axially beyond the rotor on its upper side, wherein the casing of the cylindrical hollow body consists of a plurality of strip-shaped, radially oriented baffles and is arranged on a support device, • the support device has a bottom surface , a spacer and a vortex breaker , • the stator is spaced from the bottom surface by the spacer of the vortex breaker , • the top surface, opposite the bottom surface, of the stator has an opening, which is constructed in such a manner that the rotor can be passed through it and the opening is surrounded by a cover ring , which seals the baffles in an axial direction, • at least one opening for the intake of air into the suspension is arranged on the hollow drive shaft of the rotor , below the plate of the rotor , in the region of the vanes , characterized in that • the rotor has vanes , which extend from the plate in an axial direction to varying distances, • at least two vanes of the rotor , which are arranged in the circumferential direction of the drive shaft , have a radial distance r to the axis of rotation , a first portion of the baffles of the stator runs at an angle α of 30° to 60°to the axis of rotation and a second portion of the baffles of the stator runs at an angle α' of -30° to -60° to the axis of rotation and the angles α and α' have the same value, and • the baffles of the stator are connected to each other. <EOS>