Patent ID: 8870109

Claim:
A method of operating a disc refiner for refining a low consistency paper pulp, comprising the steps of using a disc refiner, providing a pair of refining discs for the refiner, said pair of refining discs being a stator and a rotor, both the stator and the rotor including a disc-shaped metallic element with a refining surface having alternating bars and grooves, wherein the stator and the rotor surfaces are always parallel to each other, and having a pre-set inclination angle greater than 0° in respect of a plane perpendicular to the rotor axis of rotation, wherein all the bars of the stator and the rotor surfaces having the same height and all the grooves of stator and the rotor surfaces having the same depth and the opposed surfaces of both the stator and the rotor have inclined profiles in cross section, the method further including the steps of driving the rotor to rotate around its own axis of rotation, passing the axis through the center of the disc refiner, performing a rotary movement with the rotor bars in front of the stator bars with a gap in between, providing said gap with a constant height over the whole surfaces of the opposed discs, and wherein the fibers are not refined individually but in flakes with consistency between 2% and 6% where low density refinement is located and fibers are not free to move independently.