EP 0466752 B1 19960710 - A PROCESS FOR BLEACHING A FIBER PULP WITH A CHEMICAL SOLUTION
Title (en)
A PROCESS FOR BLEACHING A FIBER PULP WITH A CHEMICAL SOLUTION
Title (de)
VERFAHREN ZUM BLEICHEN EINES FASERPULPS MIT EINER CHEMISCHEN LöSUNG
Title (fr)
PROCEDE DE BLANCHIMENT D'UN PATE DE FIBRES AU MOYEN D'UNE SOLUTION
Publication
Application
Priority
- FI 9000095 W 19900406
- FI 891662 A 19890407
Abstract (en)
[origin: WO9012146A1] The process relates to continuous treatment of a fiber pulp with a chemical solution by forming on a filter surface a bed of a fiber material suspension and by feeding it through one or several chemical treatment steps in which the chemical solution is displaced through the bed. According to the method, there are used in each treatment step two different treatment liquids which are successively displaced through the bed. The first treatment solution is a chemical solution which contains a greater amount of active chemicals than is consumed in the reactions occurring in the pulp bed, preferably approx. twice the amount. The second treatment liquid is a solution which does not contain active chemicals in an amount significant in terms of the reaction. Its purpose is not only to displace that portion of the first treatment liquid from which the active chemicals have been spent but also that portion which still contains active chemicals upon leaving as a filtrate. Of the filtrate of the treatment step, that fraction is recovered which has the highest concentration of active chemicals and contains most of the active chemicals leaving the bed and is in its amount only so large that, when reinforced with a fresh chemical solution, it can be used in its entirety as the first treatment solution. The total liquid volume of the treatment liquids is substantially greater than the liquid volume present in the bed upon its leaving the treatment step - preferably 2- to 3-fold.
IPC 1-7
IPC 8 full level
D21C 9/06 (2006.01); D21C 9/10 (2006.01); D21C 11/00 (2006.01)
CPC (source: EP)
D21C 9/06 (2013.01); D21C 9/1031 (2013.01); D21C 11/0028 (2013.01)
Designated contracting state (EPC)
AT BE CH DE DK ES FR GB IT LI LU NL SE
DOCDB simple family (publication)
WO 9012146 A1 19901018; AT E140282 T1 19960715; AU 5420190 A 19901105; AU 647020 B2 19940317; BR 9007276 A 19920317; CA 2049951 A1 19901008; DE 69027770 D1 19960814; DE 69027770 T2 19961128; EP 0466752 A1 19920122; EP 0466752 B1 19960710; ES 2091240 T3 19961101; FI 85513 B 19920115; FI 85513 C 19920427; FI 891662 A0 19890407; FI 891662 A 19901008; JP H05500835 A 19930218; NO 176485 B 19950102; NO 176485 C 19950412; NO 913904 D0 19911004; NO 913904 L 19911004; NZ 233237 A 19930225; ZA 902703 B 19941007
DOCDB simple family (application)
FI 9000095 W 19900406; AT 90905528 T 19900406; AU 5420190 A 19900406; BR 9007276 A 19900406; CA 2049951 A 19900406; DE 69027770 T 19900406; EP 90905528 A 19900406; ES 90905528 T 19900406; FI 891662 A 19890407; JP 50579190 A 19900406; NO 913904 A 19911004; NZ 23323790 A 19900406; ZA 902703 A 19900409