The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 10, 1980
Filed:
Oct. 25, 1978
Jonas A Lindahl, Domsjo, SE;
Mo och Domsjo Aktiebolag, Ornskoldsvik, SE;
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 water comprising spent bleaching liquor at a temperature of at least 70.degree. C. and forming a pulp suspension in the resulting aqueous liquor; centrifugally separating steam from the pulp suspension and using the separated hot steam to heat spent bleaching liquor supplied for the grinding; thickening the pulp suspension to a concentration within the range from about 5 to about 40% and supplying water separated therefrom to the grinding; diluting the pulp suspension to a concentration within the range from about 0.5 to about 4.0%; screening the pulp suspension; thickening the pulp suspension to a concentration within the range from about 10 to about 50% and supplying water separated therefrom to the screening; adding bleaching chemicals to the pulp and bleaching the pulp; diluting the bleached pulp with spent bleaching liquor to a concentration within the range from about 1 to about 6%; thickening the bleached pulp suspension to a concentration within the range from about 10 to about 50%; and separating, heating and recycling to the grinding spent bleaching liquor containing residual bleaching chemicals.