Abstract: An injector of a flotation cell, the injector comprising a feed pipe for feeding a fiber suspension flow into the flotation cell, a mixing apparatus for mixing air into the fiber suspension flow and at least one air feed connection arranged before the mixing apparatus for feeding air into the injector. The injector further comprises a nozzle section which is arranged before the mixing apparatus and comprises an aperture plate provided with apertures and nozzles fixed to the aperture plate substantially at the apertures after the aperture plate, there being open spaces between the nozzles. The air to be fed from the air feed connection is arranged to flow into the spaces between the nozzles and further into the mixing apparatus with the partial flows of the fiber suspension flow entering from the nozzles.

Abstract: The invention relates to a method for defibering recycled fiber material in a drum pulper provided with a substantially horizontal drum. Recycled fiber material and water are fed to the drum pulper and the drum of the drum pulper is simultaneously rotated. When the drum rotates, the recycled fiber material rises up in the rotating drum and finally, due to gravitational force, falls back down. After falling and hitting to the bottom, the recycled fiber material is defibered, forming a fiber pulp mixture with water. A value of at least one parameter describing the defibration process or fiber pulp properties is measured on the basis of the drum pulper or the resultant fiber pulp mixture, and this value is used for controlling the rotation speed of the drum of the drum pulper. The invention also relates to a drum pulper implementing the method of the invention.

Abstract: The object of the invention is a method and a device for dispersing pulp, especially pulp containing waste paper, in which method ground pulp mass is fed between the blade surfaces (4) of a dispersing device that are brought in a rotating movement in relation to one another. The invention is characterized in that the dispersing event takes place in a narrow opening (5) between the conical surfaces (3) at the outlet end (6) of which there is arranged a running wheel (7) acting as pump by which the pulp is pumped out of the dispersing device by centrifugal force. The inner cone of the dispersing device may act as rotor and the outer cone may act as stator. In addition, the pulp may be diluted at the outlet end of the blade opening (5) with fluid introduced to the intake side of the running wheel (7).