Toward Mill Closure: Lessons Learned, 1996 Minimum Effluent Mills Symposium Proceedings

Fred Martin, John Nepote, Kirk Girard and Anton Jaegel- Louisiana Pacific Corporation

Yongxiang Gu and Lou Edwards

University of Idaho

Mill trials supported by detailed process simulation show that successful countercurrent washing in a hydrogen peroxide based TCF fiber line requires low levels of manganese entering the chelation stage (Q-stage). Specifically, with 60 ppm manganese in the second post oxygen washer pulp mat, an increase in manganese from 8 to 21 ppm in the Q-mat pulp occurred when about half of the Q-filtrate was recycled to the second post oxygen washer shower. In contrast, when manganese in the second post oxygen washer mat was 20 ppm, the manganese level in the Q-mat actually decreased by about 25% when Q-filtrate was recycled. Simulation results confirm these mill results. A Lo-Solid cooking mill trial showed more than a 20% reduction in manganese (and calcium) in the brown stock. Thus Lo-Solids cooking will facilitate fiber line closure.