Canadian Forest Service Publications
Assessment of the economic (pulping and pulp quality) effects of increased lodgepole pine in SPF chip mixtures. 2008. Dalpke, B.; Hussein, A.; Trent, T.; Gee, W.; Johal, S.; Yuen, B.; Watson, P.A. Natural Resources Canada, Canadian Forest Service, Pacific Forestry Centre, Victoria B.C. Mountain Pine Beetle Initiative Working Paper 2007-08. 88 p.
Available from: Pacific Forestry Centre
Catalog ID: 28840
British Columbia's market pulps and mechanical printing papers enjoy an enviable reputation worldwide as the benchmark for intrinsic strength and quality. Spruce-pine-fir (SPF) chip mixtures are widely used in both interior and coastal pulping operations. The current mountain pine beetle infestation, with the increased harvest of lodgepole pine, threatens to shift the balance of SPF from the traditionally used 30/65/5 ratio to a high pine ratio of 80% to 90%. To evaluate and quantify possible process and pulp-quality implications, statistically designed pilot kraft and mechanical pulping mixing experiments using green spruce, pine and fir were undertaken. These suggest a decrease in pulp yield with increasing pine content for kraft pulping, and possibly an increase in necessary refining energy for thermomechanical pulping (TMP). A small but tolerable decrease in pulp strength is possible for kraft and TMP, whereas opacity and scattering coefficient both increase slightly. No conclusive results for change in brightness for TMP pulp were found. A thorough discussion of fibre properties showed that pine fibres are not necessarily coarser, but they do have a smaller collapse index, which can impact internal bonding and thus sheet strength; however, differences between the species found in this study are small. Pulp properties, as well as the changes with increasing pine content, were site dependent, but no correlation with site index specifically was found, possibly due to the small sample size. However, the site dependence emphasizes the importance of closely monitoring incoming wood and chip quality in pulp mills to be able to adjust process variables quickly.