Patent ID: 6080275
Filing Date: 2000-06-27
Classification: D21C

Abstract:
A method of oxygen delignification of medium consistency pulp slurry, consisting of the following sequential steps:providing a pulp slurry of from approximately ten percent to sixteen percent consistency, at a temperature of from approximately 170-240.degree. F.;adjusting the pH of the slurry to at least 11;adding oxygen gas to the slurry with agitating mixing therein the absence of H.sub.2 O.sub.2 ;reacting the slurry with the oxygen gas in a first pressurized reactor in the absence of H.sub.2 O.sub.2 other than an amount of residual H.sub.2 O.sub.2 ;adjusting the pH of the slurry to at least 11;impregnating the slurry with a first supply of H.sub.2 O.sub.2 and oxygen gas; andreacting the slurry in a second reactor at a temperature from approximately 170-240.degree. F. while maintaining the final pH to at least 10.