Abstract: Pressure screening apparatus for screening a suspension of papermaking stock employing an enclosing housing and a cylindrical screen, with a drum type rotor, has the screen divided or formed with axially spaced annular screening zones and a corresponding number of annular reject collection areas, one for each screening zone. The collection areas are positioned so as to receive rejects from one of the screening zones only, while a rotor is formed with outlet openings that apply stock suspension to selected ones of the screening zones so that there is no mixing of rejects between screening zones, and each screening zone receives stock suspension for screening independently of the other screening zones.

Abstract: Apparatus for separating contaminant particles from liquid suspension stock, e.g. in the de-inking of used news print, is characterized by one or more of a plurality of features which contribute to increasing the capacity and effectiveness of the apparatus, including the provision of a cell comprising inner and outer annular chambers of substantially equal depth with the inlet and outlet connections for the stock being located adjacent the bottoms of the two chambers to force the stock to travel through the full depth of each chamber, and also the provision of a baffle of substantial width on the top of the wall between the two chambers to spread the stock overflowing that wall into a thin film.

Abstract: A system for the recovery of paper-making fiber from contaminated waste paper products including plastic film and other lightweight non-paper contaminants includes a novel rotary screening machine comprising a perforated drum rotatable about a generally horizontal axis and having openings at opposite ends for the delivery of liquid and paper furnished to the drum and the discharge of contaminants, respectively, a plurality of vanes for lifting material from the bottom of the drum to an upper region as the drum rotates, and a rotor mounted within the drum and having blades which are disposed in spaced relation to the drum vanes in a position to intercept material falling from the upper region of the drum and fling it back against the drum. The resulting fibers or flakes of useful paper are washed through the drum perforations while the rejected contaminants are conveyed to and removed via the discharge end of the drum.