http://cfs.nrcan.gc.ca/authors/read/20482?format=citation Publications by B. Yuen en-ca 2009-02-11 00:00:00 MST 2009-02-11 00:00:00 MST webmaster@nofc.cfs.nrcan.gc.ca http://cfs.nrcan.gc.ca/publications?id=29243 Pilot-plant thermomechanical (TMP) pulping has been performed on green and dry, blue-stained grey-stage lodgepole pine (LPP) chips with different moisture contents. The energy requirements for TMP pulping of the dry, early-grey (kill date approximately 4 years) chips and the dry, late-grey (kill date approximately 6 to 8 years) chips were similar to those for TMP pulping of the green chips, when all the results were taken into consideration. The early-grey and late-grey TMP pulps had lower sheet density and ISO brightness, and higher handsheet surface roughness than the green TMP pulps. No significant difference in long-fibre and fines contents, fibre-length or tensile strength was observed between the green and the early-grey TMP pulps at the same freeness, while indications of a slightly lower tensile index were found for the late-grey TMP. The late-grey TMP also showed a higher light scattering coefficient at a given Canadian Standard Freeness (CSF).</p> <p>The higher handsheet surface roughness of the late-grey and early-grey TMP pulps was not due to the low moisture content of the late-grey and early-grey chips, but likely due to other changes. The maximum level of the dry, late-grey chips that could be added to the green chips without significantly increasing the surface roughness or lowering the sheet density was 25%.</p> <p>Low-intensity refining in the post-primary stages of the early-grey and the late-grey TMP improved the fibre length, but did not affect the tensile index at a given CSF significantly. Chip presteaming and water impregnation had a marginal effect on the pulp properties of the late-grey TMP. However, sodium sulfite pretreatment at pH=6 coupled with low-intensity refining of the late-grey chips had a positive effect on the tensile index at a given CSF. Process modifications involving careful sulphite pretreatment could be investigated further if loss of tensile strength due to beetle-killed wood becomes a greater problem in the future. Reducing the refining intensity may be a solution if maintaining the fibre length becomes a critical issue. Both these modifications led to somewhat increased refining energy consumption to reach a given CSF.</p> <p>Increase of moisture content/water impregnation of the early- and late-grey LPP chips could be achieved by increasing chip presteaming temperature/pressure and/or time, by increasing the water impregnation time, or by controlling the conductivity and pH of the impregnating water at _{200 ?S/cm and}6.0, respectively. The most economical pretreatment approach to increasing the moisture content of the dry, grey-stage LPP chips prior to TMP pulping appeared to be presteaming at moderate temperature/pressure, followed by 8 to 10 minutes of chip washing with proper control of the conductivity and pH of the chip washing water.</p> <p>Soaking of the green and the late-grey blocks in a 10% AgNO3 solution, followed by ESEM-EDS analysis of Ag intensity, could provide qualitative information on the movement of water within 10 minutes of water soaking/impregnation. ESEM-EDS results on the green and late-grey blocks are consistent with the water-uptake results obtained using Weyerhaeuser test apparatus. Dry late-grey LPP chips behaved very differently during TMP pulping or water/chemical impregnation than green LPP chips air-dried to the same starting moisture content. Wed, 11 Feb 2009 http://cfs.nrcan.gc.ca/publications?id=29243 http://cfs.nrcan.gc.ca/publications?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.</p> <p>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.</p> <p>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. Tue, 30 Dec 2008 http://cfs.nrcan.gc.ca/publications?id=29131 http://cfs.nrcan.gc.ca/publications?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. Wed, 13 Aug 2008 http://cfs.nrcan.gc.ca/publications?id=28840 http://cfs.nrcan.gc.ca/publications?id=26813 Thermomechanical and chemithermomechanical pulps were prepared and tested from blue-stained and sound lodgepole pine samples. Blue-stained samples had higher amounts of fine and pin chip content and slightly less basic chip density than did the sound samples. There was no well-defined relationship between refining energy, fibre properties, strength properties, or optical properties of thermomechanical and chemithermomechanical pulps prepared from blue-stained and sound lodgepole pine chips. Blue-stained pine thermomechanical pulping responded poorly to sodium hydrosulfite bleaching, but responded to alkaline hydrogen peroxide bleaching as well as the unstained pine thermomechanical pulping did at high peroxide charges. The light stability of the peroxide-bleached, blue-stained thermomechanically pulps was identical to that of the peroxide-bleached, unstained thermomechanical pulps. Blue-stained pine chemithermomechanical pulps also responded poorly to sodium hydrosulfite bleaching, but responded to alkaline hydrogen peroxide bleaching better than did the unstained pine chemithermomechanical pulps. The light stability of the peroxide-bleached, blue-stained chemithermomechanical pulps was also slightly higher than that of the peroxide-bleached, unstained control. The hydrosulfite-bleached, blue-stained thermomechanical or chemithermomechanical pulps had the advantage of low yellowness (CIE b*) over the bleached, unstained pulp. Fri, 23 Mar 2007 http://cfs.nrcan.gc.ca/publications?id=26813 http://cfs.nrcan.gc.ca/publications?id=26719 The impact of using a portable in-woods chipper (Peterson DDC 5000) to chip red- and grey-stage mountain pine beetle-infested lodgepole pine (Pinus contorta) was determined from the perspective of chip quality, pulping (thermomechanical [TMP] and kraft) and pulp quality. In addition, the costs of chipping were determined and compared. Chips made by the Peterson DDC 5000 were of acceptable quality for both TMP and kraft pulping. Differences noted in the pulping and refining, albeit minor, could be linked to chip quality. Chip quality, in turn, was affected as much by seasonal chipping conditions as by wood quality. The chips made from portable in-woods chippers would be too expensive in the current chip market to be attractive to the British Columbia pulp industry or for export. Also of note was the lack of hog fuel generated by the chipper. This was due to the loss of bark in the advanced grey stage wood. Recommendations for future work include a means of assessing checking on standing timber, an assessment of bark remaining on standing timber, and optimization of chip-size distributions for mountain pine beetle. Thu, 01 Feb 2007 http://cfs.nrcan.gc.ca/publications?id=26719