Process to remove printing ink from recycled paper by selective floatation and separation of fibers into coarse and fine fractions

摘要

In a process to recycle pre-used paper the paper is soaked to disperse fiber in suspension (S) and remove printing ink by selective floatation. Prior to the dispersion process (4) the suspension is sub-divided into fractions (3) consisting of a fine (F) and coarse (G) fiber fractions. The coarse fraction (G) is released for dispersal (4) without the fine fraction. The fine fraction (F) is subsequently added to the treated coarse fibers after treatment (S) in the dispersion stage. Printing ink is removed from the resulting combination (S) in a floatation stage (2). The resulting rejected substances (R2) are surrendered to a trap while the cleaned fibers (A2) continue for further treatment. The coarse fraction (G) is cleaned by sieve sorting (5) prior to the dispersion stage (4).