Paper making and fiber liberation – Processes of chemical liberation – recovery or purification... – With agitation or forced circulation
Patent
1997-10-14
2000-12-19
Alvo, Steve
Paper making and fiber liberation
Processes of chemical liberation, recovery or purification...
With agitation or forced circulation
162 65, 162 90, D21C 9147
Patent
active
061623245
ABSTRACT:
An improved process is described for oxygen delignification of medium consistency pulp slurry which teaches control parameters and their resultant effect on final product characteristics. Specifically, a process is described wherein pulp slurries of from approximately eight percent to sixteen percent consistency, are heated to a temperature of at least 170.degree. F. and impregnated oxygen gas and alkali to bring the slurry to a pH of from approximately 11-12.5. The slurry is mixed in a high shear mixer, for agitating mixing therein, under pressure of from approximately 20-180 psig for a first reaction time of typically 5 minutes. Additional alkali is added to the slurry to return the pH to at least 11, preferably at least 12, and the residual alkali concentration to at least 4.0 gpl at the end of the first reaction time. The temperature of the slurry is raised to at least 170.degree. F. followed by mixing for a second reaction time of typically 55 additional minutes.
REFERENCES:
patent: 3719552 (1973-03-01), Farley et al.
patent: 3843473 (1974-10-01), Samuelson et al.
patent: 3951733 (1976-04-01), Phillips
patent: 4093506 (1978-06-01), Richter
patent: 4363697 (1982-12-01), Markham et al.
patent: 4842690 (1989-06-01), Gazdik et al.
patent: 5011572 (1991-04-01), Parthasarathy et al.
patent: 5034095 (1991-07-01), Kido et al.
patent: 5145557 (1992-09-01), Peter et al.
patent: 5296099 (1994-03-01), Griggs et al.
"The Efficient Use of Hydrogen Peroxide as a Chemical Pulp Delignification Agent", by Troughton and Sarot, TAPPI Proceedings 519-535 (1992).
"The Function of Magnesium Compounds in an Oxygen-Alkali-Carbohydrate System", by Sinkey and Thompson, Paperi ja puu, No. 5, 473-486 (1974).
"OZP-Bleaching of Kraft Pulps to Full Brightness", by U. Germgard and S. Norden, Intl. Pulp Bleaching Conf., 53-58 (1994).
"Pressurized Hydrogen Peroxide Bleaching for Improved TCF Bleaching", by Bertil Stromberg and Richard Szopinski, Intl. Pulp Bleaching Conf., 199-209 (1994).
Alvo Steve
Beloit Technologies Inc.
LandOfFree
Oxygen delignification of medium consistency pulp slurry using t does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Oxygen delignification of medium consistency pulp slurry using t, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Oxygen delignification of medium consistency pulp slurry using t will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-268201