Introduction of Soluble MgSO4 in Peroxide - Reinforced Oxidative Extraction at Fort James, Camas, 2000 Pulping / Process & Product Quality Conference Proceedings

M. Gavriliu, J. Irving, D. Chappel--It is recognized that soluble magnesium sulphate addition to an oxygen delignification system is an effective method of improving reaction selectivity of both softwood and hardwood Kraft pulps. Similarities between the chemistry of oxygen delignification and alkaline extraction reinforced with oxygen and hydrogen peroxide (Eop) would lead to the conclusion that magnesium sulphate should work in the Eop stage to protect pulp viscosity, improve peroxide utilization, and reduce chemical costs. There have been very few documents published that explain the Eop response characteristics of kraft pulps with the addition of magnesium sulphate.

This paper presents laboratory results used to recommend a mill trial at the Fort James mill in Camas, WA. The laboratory results are analyzed in the context of optimum bleach plant performance. The chemistry of the observed responses under Eop conditions is discussed. Both the laboratory results and mill trial results were in agreement, confirming an increase of 10% ISO brightness after the Eop stage, and a viscosity improvement of around 70%. Substantial chemical usage savings were achieved in the mill.