Optimization of elemental chlorine-free bleaching for a softwood kraft pulp part 2: economic analysis of chemical and steam consumption

Our previous investigation [1] re-analyzed the data from Basta and co-workers (1992 TAPPI Pulping Conference) to demonstrate how oxidative alkaline extraction can be augmented and how these changes affect chlorine dioxide consumption with elemental chlorine-free (ECF) sequences. The current study manipulates extraction delignification variables to curtail bleaching costs with a conventional U. S. Southern softwood kraft pulp. The economic advantages of similar to 0.35% to 0.65% H2O2 peroxide reinforcement in a 70 degrees C (EOP)-stage versus 90 degrees C (EO)-stage are predisposed to the brightness targets, to short or long bleach sequences, and to mill energy costs. Minimized bleaching costs are generally realized when a 90 degrees C (EO) is employed in D-0(EO) D-1 bleaching, whereas a 70 degrees C (EOP) is economically advantageous for D-0(EOP)D1E2D2 bleaching. The findings we disclose here help to clarify previous ECF optimization studies of conventional softwood kraft pulps.