Optimizing kraft cooking; pulp yield vs. HexA content and the effect of HexA content after cooking on the bleaching chemical requirement
2007 (English)In: O Papel, ISSN 0031-1057, Vol. 68, no 6, 64-85 p.Article in journal (Refereed) Published
Using modern cooking concepts for the manufacture of hardwood kraft pulp, a higher pulp yield is obtained, mainly as a result of high xylan retention. This often leads to a somewhat higher HexA content of the pulp at a given kappa number. Pulp yield is the most important factor for cost-effective pulp manufacture. Hence, cooking to a low pulp yield in order to reduce the HexA content is not an attractive alternative. Questions have been raised as to whether a pulp with a high HexA content requires more bleaching chemicals to reach a given ISO brightness or shows a higher yellowing. The results of this study show that a high HexA content after cooking may have a positive effect in achieving a low bleaching chemical requirement in a contemporary bleaching sequence. The pulps having a high HexA content after cooking did not show a higher yellowing tendency than the pulps originally having a low HexA content. Optimization of the kraft cook in a hardwood pulp mill towards a high yield can therefore be made without penalties in the form of an increased bleaching chemical consumption, but instead often leads to lower bleaching chemical consumption.
Place, publisher, year, edition, pages
2007. Vol. 68, no 6, 64-85 p.
Bleaching, Hexenuronic acid content, Kraft cooking, Oxygen delignification, Pulp yield
Paper, Pulp and Fiber Technology
IdentifiersURN: urn:nbn:se:kth:diva-6618ScopusID: 2-s2.0-36348962469OAI: oai:DiVA.org:kth-6618DiVA: diva2:11375
QC 20120316. Updated from manuscript to article in journal.
[Otimização do cozimento kraft; rendimento da polpa em relação ao teor de HexA e o efeito do teor de HexA pós cozimento na demanda de produtos químicos de branqueamento]2006-12-132006-12-132014-11-10Bibliographically approved