A method for decolorize and cleaning of paper material

摘要

1,206,550. Centrifuging paper stock. BERGSTROM PAPER CO. 21 Aug., 1969 [4 June, 1969], No. 41708/69. Heading B2P. In a process of de-contaminating reclaimed paper, a slurry of water and defibered, contaminated fibre stock obtained from the paper is fed into a hydrocyclone to create therein a vortex and a first part of the slurry relatively enriched by fibres is extracted from an outer region of the vortex while the remainder of the slurry relatively enriched by contaminants is extracted from an inner region of the vortex. The migration of the fibres to the outer region of the vortex, while the contaminants are left in the outer region, may be obtained as a result of the relation existing between the cross sectional size of the overflow and underflow outlets. In a typical example the diameter of the overflow outlet is 5/8" and that of the underflow 1/2". The slurry may have a consistancy of 0.10% to 1.50% and may be fed at a pressure of 40 to 100 p.s.i.g. The contaminants include those with a specific gravity less than that of water, e.g. plastics polymers, adhesives, &c. and those with a specific gravity greater than that of water and that of fibres, e.g. clays, pigment fillers and ink particles. The latter because of their minute size and/or platelike shape have a higher coefficient of hydraulic, drag as compared with the fibres, and are therefore held back in greater degree that the fibres from their natural tendency to migrate to the outer portion of the vortex.