Abstract: A method and device for processing sewage which contains coating paste from a paper or board mill with a device operating on the principle of a double action impact mill. The device includes a first rotor (11) equipped with blades; a second rotor (12) concentric with the first rotor, equipped with blades and arranged to rotate in a direction opposite to the direction of the first rotor, or a stator concentric with the first rotor and equipped with blades. The sewage is led to a feed opening (14) which opens out to the nave of rotors (11, 12) or to the nave of the rotor and the stator. In the device, the material flow is brought to flow as a flow-off through the blades of the rotors (11, 12) arranged within each other, or of the rotor and the stator arranged within each other.

Abstract: A method and device for defibrating fiber-containing material in a device operating with the pin mill principle. The device includes a housing and in it a first rotor equipped with collision surfaces; a second rotor concentric with the first rotor and equipped with collision surfaces, the second rotor being arranged to rotate in a direction opposite to the first rotor; or a stator concentric with the first rotor and equipped with collision surfaces. Further, the device includes a feed orifice in the housing and opening to the center of the rotors or the rotor and stator, and a discharge orifice on the housing wall and opening to the periphery of the outermost rotor or stator. The fiber-containing material is led from the feed orifice to the housing and made to flow together with air or liquid generating a suspension through the collision surfaces of the nested rotors, or the nested rotor and stator to the discharge orifice and further as a discharge flow out of the housing.