Review on Increasing the Kappa Reduction in Oxygen Delignification Stage at Pulp Mills

The use of oxygen delignification in bleached kraft pulp mills to reduce the lignin content of pulp prior to final bleaching is increasing worldwide.  However, oxygen treatments are normally limited to less than 50% lignin removal to avoid excessive loss of pulp strength potential.  More selective oxygen delignification processes are required which can extend lignin removal beyond 50% while maintaining final pulp quality.  Work reported here has shown that pulp treatment with small amounts of peroxymonosulfuric acid between two oxygen delignification stages improves overall selectivity.  This Non-chlorine Psa sequence achieved greater than 70% delignification Keywords: Pulp, Lignin, Treatment, Delignification, Non-chlorine, Strength.