Effects of Extractives from Mountain Pine Beetle-Attacked Lodgepole Pine on Kraft Mills

摘要

This report addresses the impact of mountain pine beetle infestation on several extractives-related issues in kraft pulp mill operation: extractives in pulp, pitch control, and effluent treatment. The work, funded by the Mountain Pine Beetle Initiative of Natural Resources Canada, involved visits to five western Canadian kraft mills to observe operating conditions, collection of samples for subsequent laboratory measurements, and overall analysis of the combined information. Work in separate reports has shown that the use of infested wood usually causes higher extractives (especially increased resin acid content) in the wood to the digester and this results in an increased solubility of fatty and resin acid soaps in black liquor. Hence the use of infested wood resulted in a greater extractives load to be removed in brownstock washing for good pitch control. Use of green- and red-stage wood did not cause a significant change in the normal quantities of extractives in pulp across the bleach plant and at the pulp machine. In the mill using grey-stage wood, the solubility of extractives in black liquor was even higher and brownstock washing was more important for their removal. The quantity of extractives, especially the unsaponifiables, in the final pulp was significantly higher in the mill using grey-stage wood. In this mill, the resin acid concentration in the final effluent was high. The grey-stage results require further confirmation in more mills.