Effects of Several Factors on Medium Consistency Oxygen Delignification, 1996 International Pulp Bleaching Conference Proceedings

This study was conducted on hardwood brownstock pulp(predominantly Eucalyptus wood) to determine the effects of several factors on medium consistency(MC) oxygen delignification(O2 D) performance. Delignification experiments were performed in a laboratory MC mixer. The experiments were designed for the influence of mixing intensity, the effects of type of carryover on the reaction, the influence of carryover from pre-oxygen washing system on the kinetics of O2 D, and the effect on the delignification rate with the addition of hydrogen peroxide&O:) during O2 D reaction, Intensive mixing of the pulp suspension at the moment of injection of oxygen improved delignification. But even without high intensity mixing, 37.1% of delignification was achieved. Carryover of the filtrate from the cooking stage was more detrimental to delignification than carryover of the filtrate from the O stage. Delignification took place in two phases ; a rapid initial phase and a slower secondary phase. In the case when the carryover of the filtrate from the cooking stage was present, there could be competitive reactions between lignin in the pulp