Title (en)

METHOD FOR PREVENTING ACCUMULATION OF METALS IN A CLOSED PULP BLEACHING PROCESS

Title (de)

VERFAHREN ZUR VERHINDERUNG DER METALLANHÄUFUNG IN EINEM GESCHLOSSENEN VERFAHREN ZUR ZELLSTOFFBLEICHUNG

Title (fr)

PROCEDE POUR EMPECHER L'ACCUMULATION DE METAUX DANS UN PROCESSUS DE BLANCHIMENT DE PATE A PAPIER EN CIRCUIT FERME

Publication

EP 0847460 A1 19980617 (EN)

Application

EP 96929609 A 19960809

Priority

• SE 9600997 W 19960809
• SE 9503004 A 19950830

Abstract (en)

[origin: WO9708381A1] A method at the bleaching of pulp, comprising bleaching with peracetic acid where the pH value during the bleaching reaction is held within 5-7. In the final phase of the bleaching with peracetic acid, metals released in the pulp are rebound to the fibers in the pulp by increasing the pH value to at least 9, whereafter the pulp is washed. The pH value is increased preferably 1-10 minutes before the washing. It is thereby possible to close the bleaching process in counterflow without risk of accumulation of the metals in the process.

IPC 1-7

D21C 9/16; D21C 9/10

IPC 8 full level

D21C 9/10 (2006.01); D21C 9/16 (2006.01)

CPC (source: EP)

D21C 9/1026 (2013.01); D21C 9/166 (2013.01)

Citation (search report)

See references of WO 9708381A1

Designated contracting state (EPC)

AT DE ES FI FR PT SE

DOCDB simple family (publication)

WO 9708381 A1 19970306; AU 6892696 A 19970319; BR 9610198 A 19990629; CA 2229893 A1 19970306; EP 0847460 A1 19980617; NO 980872 D0 19980227; NO 980872 L 19980227; SE 9503004 D0 19950830; SE 9503004 L 19970301

DOCDB simple family (application)

SE 9600997 W 19960809; AU 6892696 A 19960809; BR 9610198 A 19960809; CA 2229893 A 19960809; EP 96929609 A 19960809; NO 980872 A 19980227; SE 9503004 A 19950830