Paper making and fiber liberation – Processes of chemical liberation – recovery or purification... – Treatment with particular chemical
Patent
1991-11-25
1993-06-29
Jones, W. Gary
Paper making and fiber liberation
Processes of chemical liberation, recovery or purification...
Treatment with particular chemical
162 78, 162 79, 162 76, 162 80, 162 82, 162 86, D21C 104
Patent
active
052230910
ABSTRACT:
A method of brightening mechanical pulps by chelating and thickening to reduce the manganese content of the pulp to less than 30 parts per million and copper content less than 1 parts per million by adding ions preferably magnesium ions as magnesium sulphate MgSO.sub.4 in the amount of 400 to 3,000 ppm Mg ions retained by the pulp based on the oven dry weight of the pulp and thereafter applying a bleaching liquor composed of peroxide as hydrogen peroxide and an alkali as sodium hydroxide having a ratio of alkali to peroxide of between 1--1 and 2-1 in an amount to apply between 1 to 8 percent peroxide based on the oven dry weight of the pulp and containing no added sodium silicate. Preferably the bleaching liquor will contain magnesium sulphate in the amount of about 0.001 to 0.1% based on the oven dry weight of the pulp. The treated pulp is bleached in a bleaching tower for a sufficient time to obtain the desired degree of brightening and thereby produce a pulp having a brightness at least equivalent to that obtained by bleaching using a silicate stabilized bleaching liquor and the equivalent amount of peroxide.
REFERENCES:
patent: 2820690 (1958-01-01), Feldman
patent: 3860391 (1975-01-01), Kling et al.
patent: 4614646 (1986-09-01), Christiansen
patent: 4731161 (1988-03-01), Erhardt
patent: 4732650 (1988-03-01), Michalowski et al.
patent: 4798652 (1989-01-01), Joyce et al.
patent: 4849053 (1989-07-01), Gentile, Jr. et al.
patent: 4859283 (1989-08-01), Jayawant
patent: 4915785 (1990-04-01), Siminoski et al.
patent: 4938842 (1990-07-01), Whiting et al.
patent: 4946556 (1990-08-01), Prough
Factors Affecting H.sub.2 O.sub.2 stability in the Brightening of mech. & chemi-mechanical pulps. Part III: H.sub.2 O.sub.2 stability in the presence of Mg & combinations of Stabilizers, Colodette, J. L. Rothenberg, S.; Deuce, C. W., from the Journal of Pulp and Paper Science: vol. 15, No. 2, Mar. 1989.
Eadie Donald T.
Hetzler Bernard H.
Turnbull James K.
Jones W. Gary
MacMillan Bloedel Limited
Nguyen Dean Tan
Rowley C. A.
LandOfFree
Method of brightening mechanical pulp using silicate-free peroxi does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of brightening mechanical pulp using silicate-free peroxi, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of brightening mechanical pulp using silicate-free peroxi will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1752620