Paper making and fiber liberation – Processes of chemical liberation – recovery or purification... – With regeneration – reclamation – reuse – recycling or...
Patent
1975-09-16
1979-02-27
Bashore, S. Leon
Paper making and fiber liberation
Processes of chemical liberation, recovery or purification...
With regeneration, reclamation, reuse, recycling or...
162 43, 162 44, 162 50, 162 83, 162 84, 162DIG2, D21C 106, D21C 306, D21C 308, D21C 310
Patent
active
041417879
ABSTRACT:
Chemical cellulose is produced by treatment in a digester. In the first step, wood in the form of chips is treated for a period of about from 15 to 90 minutes with a cooking acid of a calculated amount of below 5% by weight and at least 2.5% by weight of SO.sub.2 and a mole ratio of SO.sub.2 to MgO or CaO of from about 2 : 1 to 3.5 : 1 at a temperature of from about 45 to 90.degree. C. The liquid SO.sub.2 is fed into the digester until the total SO.sub.2 content of the cooking acid is from about 6 to 10 percent by weight, and completing the digestion in a second step to obtain a pulp by cooking at a temperature of above 110.degree. C., and working up the pulp in a manner known per se to obtain chemical cellulose.
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Parfenova, "Increasing the Yield and Improving the Quality of Sulfite Pulp by Multistage Cooking" Bumazh, Prom, No. 7:11-12 (Jul. 1970), A.B.I.P.C. Abstract #5374, vol. 41, No. 6 (Dec. 1970).
Mencher, "Bisulfite Semichemical Pulp Optimization of the Stepwise Bisulfite/Sulfite Cooks" 12v. VUZ, Lesnoi Zh. 15, No. 4:121-126 (1972), A.B.I.P.C. Abstract #10632 vol.
Parfenova et al., USSR Pat. 403,795, 10-26-73, A.B.I.P.C. Abtract #11383, vol. 44, No. 10 (Apr. 1974).
Alvo Steve
Bashore S. Leon
PWA Papierwerke Waldhof-Aschaffenburg Aktiengesellschaft
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