GB904279A - Method of processing waste paper - Google Patents

Abstract

904,279. Producing clean pulp from waste paper. BUTLER CO. Aug. 27, 1959, No. 29305/59. Class 96. In producing clean pulp from waste paper, the latter is coarsely pulped in cool or cold water, e.g. in a beater or hydropulper, and then refined for a few, e.g. 1 to 5, seconds between the opposed, closely set, serrated surfaces of the discs of a high-speed refiner, e.g. of the kind described in U.S.A. Specifications 1,744,226 and 2,568,783, to reduce impurities, such as ink, starch and clay, into particles. The relative speed of the discs may be 18,000 feet per minute. The refined pulp is fed through a pipe 16 and a chamber 12, Figs. 4 and 3, into a U-shaped scrubber comprising a lower limb having a bottom wall 6 and an upper wall 7, a semi-circular end 8 and an upper limb 13 having walls 32 and 33, which converge to form an outlet 34. The scrubber has side walls 10 and 11. Jets of clean wash water are fed, at high pressure, e.g. 150 to 250 p.s.i., through perforations in pipes 20, 21, 22 and 23, into the refined pulp to disperse the fibres and particles of impurities throughout the water and lower the consistency of the pulp, which passes through the outlet 34 and is guided by an apron 15 on to the downwardly-inclined screen 36 of a dewatering device 35. As the pulp passes down the screen, water containing the impurities drains away and is guided by a draining board 37 into a sump (not shown), e.g. a settling tank, to be clarified. The cleaned pulp passes from the screen into a pulp chest (not shown). This pulp may be diluted with clarified wash water and passed through a second scrubber and dewatering device.