Process for preparing high-yield cellulose pulps by vapor phase

Details Process for preparing high-yield cellulose pulps by vapor phase Process for preparing high-yield cellulose pulps by vapor phase

1977-05-02

1979-05-01

Bashore, S. Leon

Paper making and fiber liberation

Processes of chemical liberation, recovery or purification...

Continuous chemical treatment or continuous charging or...

162 20, 162 28, 162 65, 162 68, 162 82, 162 84, 162142, 162149, 162241, D21C 102, D21C 326, D21D 130

Patent

active

041521978

ABSTRACT:
Process and apparatus are provided for the preparation of improved high-yield cellulose pulps, such as semichemical, chemimechanical, thermomechanical, and mechanical pulps, which comprises mechanically defibrating a mixture of particulate lignocellulosic materials which have been partially pulped and softened to different extents. Part of the raw lignocellulosic material is particulate form is washed, moistened with steam, impregnated with pulping chemicals and pulped to a yield of from about 65 to about 92%. Another part is treated in similar manner but either not pulped at all or, if pulped, pulped to a lesser extent. The two parts are mixed without intermediate washing, after which the mixture is subjected to a vapor phase pulping by heating to a temperature within the range from about 90 to about 200.degree. C. under pressure to obtain softening of the lignin, and delignification, after which the resulting product is mechanically defibrated to form cellulose pulp.

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Rydholm; Pulping Processes, p. 283, Interscience Publishers, N.Y. 1965.

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