Paper making and fiber liberation – Processes of chemical liberation – recovery or purification... – Continuous chemical treatment or continuous charging or...
Patent
1979-01-22
1981-02-03
Smith, William F.
Paper making and fiber liberation
Processes of chemical liberation, recovery or purification...
Continuous chemical treatment or continuous charging or...
162 25, 162 32, 162 29, 162 38, 162 40, 162 65, 162 80, D21C 302
Patent
active
042486629
ABSTRACT:
Fibrous material is pre-steamed, impregnated with alkali liquor, refined, and then oxygen pulped at a low consistency (about 3 to 8 percent solids) using an alkali liquor which contains boron compounds. The pulping step of the process is carried out in stages with recycle of liquor to preceding stages after it has been reoxygenated. By recycling a major portion of the pulping liquor, the actual liquor to fibrous material ratio at each stage of the pulping step is maintained at a relatively high level (12/1 to 30/1) while the effective liquor to fibrous material ratio for the overall process is much lower (4/1 to 8/1). This results in a bright pulp of acceptable strength as well as a high solids content spent liquor which is economically recoverable.
REFERENCES:
patent: 3215588 (1965-11-01), Kleinert
patent: 3313677 (1967-04-01), Carr
patent: 3691008 (1973-09-01), Worster
patent: 3759783 (1973-09-01), Samuelson et al.
patent: 4045279 (1977-08-01), Nagano
patent: 4089737 (1978-05-01), Nagano et al.
patent: 4116759 (1978-03-01), Janson
Markham, Canadian Pulp & Paper Assoc., vol. 4, #4, Dec. 78, pp. 110-114.
Paper Trade Journal, Jul. 15-31, 1978, pp. 37-39.
Marton et al., Empire State Pulp Research Assoc., Report No. 60, Chapter IV, Mar. 15, 1974.
Smith William F.
The Black Clawson Company
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