Abstract: Rejects from a conventional first set of cleaners from a system feeding recycled cellulosic fiber slurry to a paper machine or rejects from the paper machine approach system cleaners are fractionated to produce a first, fine fraction, stream and a second, coarse fraction, stream containing most of the fiber and larger solids. The second stream is acted upon by a disperser, deflaker, or like mechanical agitating device, to disrupt the fiber flocs and reduce the size of solids to produce a third stream containing few or no fiber flocs and no large particles. The third stream may be diluted and cleaned in a second set of cleaners, and then is returned to the first set of cleaners (e.g. to the inlet of the first stage or between the first and second stages). Ink, and other fine undesirable particles may be removed from the first stream via flotation or cleaning, and the cleaned stream may also be returned to the first set of cleaners if desired.

Abstract: A method and apparatus for the removal of light material from a fiber suspension particularly suitable for removing light compressible plastic material such as expanded polystyrene and similar material from the short circulation of a paper machine. The plastic particles containing fiber suspension is divided in a degassing tank into reject and accept flows by the assistance of vacuum. The light reject containing flow is separated from the main flow by an overflow device and recirculated to the wire pit or corresponding device. A separation device such as a vibrating screen, vibrating drum, curved screen or inverted cyclone is provided within the light reject flow return duct for removing the detrimental plastic or other light material from the short circulation and for preventing the accumulation thereof in the wire pit.

Abstract: A method and apparatus allow the efficient grading of a fiber suspension (e.g. paper pulp) having a consistency of 0.5% or more. A cyclone separator has its rejects outlet connected to a rejects chamber with a solid confining surface. A rotor is mounted for rotation in the rejects chamber adjacent its discharge opening, and accelerates the rotational speed of suspension flowing into the rejects chamber to continue the grading action of the cyclone. Accepts that are discharged from the rejects chamber are recirculated to the inlet to the cyclone separator, while the rejects are passed out for disposal or other action. Vertically extending ribs may be provided along the solid interior walls of the rejects chamber, which act with the rotor to efficiently break up fiber flocks in the suspension.