公开(公告)号：US3560330A

公开(公告)日：1971-02-02

申请号：US3560330D

申请日：1967-02-03

Applicant: STORA KOPPARBERGS BERGSLAGS AB

Inventor： AHLBORG NILS KNUT GABRIEL

IPC: D21C9/14 ,  D21C9/12

CPC classification number: D21C9/142

Abstract: BLEACHING CELLULOSE PULP IN A MULTISTAGE LPROCESS WHEREIN THE PULP AT LOW CONSISTENCY (2.5-3.5%) IS BLEACHED WITH CHLORINE, THEN TREATED WITH ALKALI TO REMOVE THE MAJOR PORTION OF THE LIGNON CONTENT OF THE PULP, AND THEREAFTER TREATED WITH AN EXCELL OF ELEMENTAL CHLORINE AT A PULP CONCENTRATION OF NOT LESS THAN 5% AND AT A TEMPERATURE OF BELOW 35*C. SMALL AMOUNTS OF CHLORINE DIOXIDE (0.52 GM./KILO OF PULP) MAY OPTIONALLY BE ADDED TO THE ELEMENTAL CHLORINE IN THE SECOND CHLORINE TREATMENT STEP. SUBSEQUENT TREATMENT STAGES MAY FOLLOW WHICH INCLUDE ALKALI WASHES AND CHLORINE DIOXIDE BLEACHINGS.