Canadian Forest Service Publications
Assessing the influence of time-since-death: Pilot scale kraft and thermomechanical pulping of beetle-killed lodgepole pine. 2008. Dalpke, B.; Hussein, A.; Johal, S.; Yuen, B.; Ortiz, D.A.; Watson, P.A. Natural Resources Canada, Canadian Forest Service, Pacific Forestry Centre, Victoria, BC. Mountain Pine Beetle Working Paper 2008-26. 77 p.
Issued by: Pacific Forestry Centre
Catalog ID: 29131
Pilot plant kraft and mechanical pulping trials were carried out for a well controlled sample set to determine the influence of TSD of mountain pine beetle (MPB)-killed lodgepole pine on pulping and pulp quality. Samples included trees of red, grey and late grey attack stages as well as unattacked trees and sample sites were established in three different biogeoclimatic subzones in British Columbia, thus accounting for natural variability. Prior to pulping, samples were tested for wood and fibre properties as well as chip quality. Kraft and thermomechanical (TMP) pulping parameters were monitored, pulp quality was determined, and sheet structure was evaluated by scanning electron microscopy.
Wood and fibre quality showed little measurable influence from TSD other than a significant drop in moisture. Kraft pulping and pulp quality was also independent of TSD, although some influence on kink index was seen which could suggest a greater susceptibility to mechanical damage for fibres from MPB-killed wood. For TMP pulp, MPB-killed wood showed lower sheet density and possibly higher sheet roughness when compared to unattacked wood. Preliminary calendering and linting tests also resulted in some differences, suggesting that runnability and printing quality of TMP paper may be affected.
The results of this study suggest that MPB-killed wood is an acceptable source of fibre for kraft pulping even at grey and late grey stages. However there are operational issues, including impacts on chemical recovery, that are being addressed in other projects. For TMP, such wood can be used with little penalty regarding pulping and strength parameters, however some effect on sheet structure and surface structure may exist which would be important in the printing paper sector. Thus, TMP results should be followed up with a more detailed study of printing behaviour of MPB-killed wood.