Filtrate treating method for use during thickening of paper fiber suspension obtained from waste paper to produce graphical paper, involves adding partial flows to filtrates, where partial flows are produced from condensed substances

摘要

The method involves adding part of solid substance contained in filtrates (F3, F6) to paper fiber suspensions (S, S') at points (11, 12) lying downstream thickening steps (3, 6). The filtrates are produced from the thickening steps and are condensed before readdition such that suspensions (13, 13') and recirculated water (14, 14') are produced. The suspensions are partially added at the points. Partial flows (15, 15', 16, 16') are added to the filtrates before filtrate thickening steps (9, 9'), where the flows are produced from condensed substances (18, 19) formed in the thickening steps.