Bleach Plant Optimization at Weyerhaeuser Canada Ltd., Grande Prairie, 1999 Pulping Conference Proceedings

Tina Larson & Grant Bourree

The Weyerhaeuser Grande Prairie mill converted to ECF bleaching in 1992. Since the successful conversion to 100% ClO2 substitution the mill has focused on optimizing the process for environmental and cost performance while enhancing product quality through variability reduction. These optimization strategies have allowed Grande Prairie to achieve world class results in these key areas and achieve the Cluster Rule objectives without the installation of oxygen delignification.

The mill produces 300,000 ADMt annually of fully bleached softwood kraft pulp. This high-grade market pulp is used as a carrier fibre for tissue and towel making and is also used for the manufacture of fine writing papers and other specialty products. White spruce and lodgepole pine is cooked to a 28 kappa in a conventional continuous digester and then bleached to a 90% ISO brightness in a DEpoDED bleaching sequence.

This paper reports on the continuing effort to optimize the bleaching process since the conversion to ECF bleaching. Particular emphasis has been placed on enhancing the uniformity of the product through reducing process variability and increasing process reliability. Results in the area of cost, quality, and environmental performance will be reviewed.