EP 0540091 A1 19930505 - Wash press modification for oxygen delignification process.
Title (en)
Wash press modification for oxygen delignification process.
Title (de)
Modifikation von einer Waschpresse zur Delignifizierung mittels Sauerstoff.
Title (fr)
Modification de presse de lavage pour procédé de delignification à l'oxygène.
Publication
Application
Priority
US 78418491 A 19911029
Abstract (en)
Unbleached pulp is washed with an aqueous alkaline solution in a wash press to substantially uniformly distribute a first amount of alkaline material throughout the pulp. The consistency of the pulp exiting the wash press is above about 18%, preferably between 25 to 35 percent by weight, and the high consistency alkali containing pulp is then treated with oxygen to effect delignification. The use of a wash press reduces the overall amounts of alkaline material utilized in the process compared to processes which add alkaline material to the pulp at low consistency. Additional alkali may be applied, if desired, onto the high consistency pulp prior to oxygen delignification to provide a total amount of between 0.8 and 7 percent by weight of oven dry pulp. High strength, low lignin pulps are formed after oxygen delignification which may be further bleached to high brightness with reduced amounts of bleaching chemicals.
IPC 1-7
IPC 8 full level
D21C 9/02 (2006.01); D21C 9/10 (2006.01); D21C 9/147 (2006.01)
CPC (source: EP KR)
D21C 9/02 (2013.01 - EP KR); D21C 9/10 (2013.01 - KR); D21C 9/1005 (2013.01 - EP); D21C 9/147 (2013.01 - EP KR)
Citation (search report)
- [AD] WO 8604938 A1 19860828 - ELTON EDWARD FRANCIS
- [AP] WO 9212288 A1 19920723 - UNION CAMP PATENT HOLDING [US]
Designated contracting state (EPC)
AT BE CH DE DK ES FR GB GR IE IT LI LU MC NL PT SE
DOCDB simple family (publication)
EP 0540091 A1 19930505; EP 0540091 B1 19970115; AT E147808 T1 19970215; AU 2716892 A 19930520; AU 647973 B2 19940331; BR 9204173 A 19930504; CA 2081398 A1 19930430; CA 2081398 C 19970325; CN 1080343 A 19940105; DE 69216757 D1 19970227; FI 924751 A0 19921020; FI 924751 A 19930430; JP H05195466 A 19930803; KR 930008238 A 19930521; KR 960006125 B1 19960509; NO 924080 D0 19921021; NO 924080 L 19930430; NZ 244837 A 19941026; SE 9203113 D0 19921023; SE 9203113 L 19930430; ZA 928294 B 19930518
DOCDB simple family (application)
EP 92203241 A 19921022; AT 92203241 T 19921022; AU 2716892 A 19921021; BR 9204173 A 19921027; CA 2081398 A 19921026; CN 92113767 A 19921029; DE 69216757 T 19921022; FI 924751 A 19921020; JP 29146992 A 19921029; KR 920019881 A 19921028; NO 924080 A 19921021; NZ 24483792 A 19921021; SE 9203113 A 19921023; ZA 928294 A 19921027