Paper making and fiber liberation – Processes of chemical liberation – recovery or purification... – Mechanical defibration in the presence of heated gas or gas...
Patent
1978-10-25
1980-06-10
Smith, William F.
Paper making and fiber liberation
Processes of chemical liberation, recovery or purification...
Mechanical defibration in the presence of heated gas or gas...
162 28, 162 45, 162 47, 162 55, 162 71, 162 78, D21B 116
Patent
active
042071399
ABSTRACT:
A process is provided for preparing groundwood pulp from debarked pulpwood logs which comprises grinding the logs under a superatmospheric pressure of a gas selected from the group consisting of steam, air and steam and air, while continuously supplying thereto process white water and water separated in thickening groundwood pulp suspension at a temperature within the range from about 75.degree. to about 100.degree. C., and forming a pulp suspension in the resulting aqueous liquor; centrifugally separating steam from the pulp suspension, and using the separated steam to heat the water supplied to the grinding; thickening the pulp suspension to a pulp concentration within the range from about 5 to about 40%, and supplying water separated therefrom to the grinding; diluting the thickened pulp, and screening the diluted pulp suspension; after thickening the screened rejects suspension to a pulp concentration of at least 10% and defibrating the screened rejects suspension in a refiner, recycling the defibrated screened rejects to the from-steam-separated pulp suspension; and mixing the thickened and refined rejects suspension, having a pulp concentration of at least 8%, with the pulp suspension, thereby increasing the pulp concentration of the from-steam-separated pulp suspension, and thus facilitating its thickening.
REFERENCES:
patent: 3808090 (1974-04-01), Logan et al.
patent: 4029543 (1977-06-01), Lindahl
patent: 4082233 (1978-04-01), Reinhall
Haikkala Pekka O.
Lindahl Jonas A. I.
Mo och Domsjo Aktiebolag
Smith William F.
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