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. 27, 2000
Filed:
May. 27, 1999
William J Miller, Manchester, NH (US);
Beloit Technologies, Inc., Wilmington, DE (US);
Abstract
A method of oxygen delignification of medium consistency pulp slurry, which includes the steps of providing a pulp slurry of from approximately ten percent to sixteen percent consistency, at a temperature of from approximately 170-240.degree. F., preferably from 190 to 220.degree. F., thoroughly impregnating the slurry with oxygen gas, and with alkali to bring the slurry to a pH of at least 11, more preferably 12, introducing the slurry to oxygen gas in a high shear mixer, for agitating mixing therein, reacting the slurry in a first pressurized reactor for between 5 to 10 minutes, returning the pH of the slurry to at least 11, more preferably 12, with a residual alkali concentration of at least 1.25 gpl, thoroughly impregnating the slurry with H.sub.2 O.sub.2 and oxygen gas, and reacting the slurry in a second reactor for between 30 to 180 minutes. By only employing the hydrogen peroxide during the slower bleaching reaction, a lower Kappa number with higher % ISO is obtained in the product, these beneficial characteristics being retained in subsequent processing steps.