Effects of the cutting pattern and log provenance on size distribution of black spruce chips produced by a chipper-canter

Abstract

Chips of black spruce (Picea mariana (Mill.) B.S.P.) logs coming from two provenances, Montmorency (at 47°N) and Chibougamau (at 50°N) sites, were produced by a chipper-canter using three cutting widths (12.7, 19.1, and 25.4 mm). Chip dimensions were assessed by thickness, width, and length (Domtar and Williams classifications). Earlywood density, latewood density, ring density, ring width, rings per mm (R/mm), shear, splitting, modulus of elasticity (MOE), modulus of rupture (MOR) in bending, and basic density (BD) were evaluated on samples obtained within each cutting width area. The results showed that these wood attributes were significantly different between sites or/and cutting widths (12.7 and 25.4 mm). The weighted mean chip thickness (WCT) and chip class distributions (Domtar and Williams) were significantly affected by site and cutting width (CW). WCT increased as cutting width increased and its value was higher at Montmorency than at Chibougamau. The differences in WCT could be associated with the variation of growth ring characteristics, mechanical properties, and BD between sites. Moreover, chip thickness (Domtar) was significantly affected by MOR and BD while chip width and length (Williams) were significantly influenced by R/mm, BD, MOR, and shear. The analyses showed the importance of growth ring characteristics, mechanical properties, and basic density on the chip size variation. Multiple linear regressions showed that CW, MOR, BD, and R/mm were the variables that better described the variation in WCT. Chip dimensions can hence be adjusted as a function of CW but they could vary depending on the provenance of the wood and their specific attributes.

The impact of log surface damage caused by harvesterEucalyptusdebarking on pulp value recovery

“…In kraft pulping, chemical penetration times vary in relation to chip size, thickness and uniformity. Uniform chips lead to more uniform pulping conditions and higher pulp recovery (Pulkki 1991;Broderick et al 1998;Ding et al 2005;True 2006;Färlin 2008;Inalbon et al 2011;Cáceres et al 2016a).…”

“…At higher MC the wood is softer and hence greater quantities of pins and fines will be produced (Watson and Stevenson 2007;Niedźwiecki 2011;Mihelič et al 2015;van der Merwe et al 2016a). No studies could be found to indicate optimal MC for chipping as wood processing is a function of the interactions between wood density and MC (Hernández and Lessard 1997;Niedźwiecki 2011;Spinelli and Magagnotti 2012;Cáceres et al 2015). Watson and Stevenson (2007) investigated the influence of seasonal variation in log MC of softwood and hardwood species on chip size and uniformity and the effect on kraft pulping.…”

“…Processing efficiencies and pulp yield can be directly related to chip quality, as chip quality plays an important role in mill pulp recovery (Hernández and Lessard 1997;MacLeod 2007;Hart 2011;Li et al 2011;Junaid et al 2015;Cáceres et al 2016a). The quality of chips derived from chippers are expressed in terms of chips size distribution, i.e.…”

“…The quality of chips derived from chippers are expressed in terms of chips size distribution, i.e. the percentage of accepted chips, prime chips, over-size chips, over-thick chips, pins, fines and whether the chips contain any impurities in the form of bark, knots and rot (Pulkki 1991;Twaddle and Watson 1992a, 1992b, 1992cMacLeod et al 1995;Uhmeier 1995;Hartler 1996;Hernández and Lessard 1997;Uhmeier and Persson 1997;Broderick et al 1998;Tessier et al 1999;Bjurulf 2005 Mafia et al 2012;Patt et al 2012;Gulsoy and Tufek 2013;Cáceres et al 2016a). In kraft pulping, chemical penetration times vary in relation to chip size, thickness and uniformity.…”

“…thickness, size distribution and chip fracturing). Chip size distribution is important as it influences pulp recovery and quality in kraft pulping (True 2006;Macleod 2007;Hart 2011;Brodin and Theliander 2013;Cáceres et al 2015;Junaid et al 2015;Trung et al 2015;Bäckström et al 2016). Chip size uniformity allow for uniform 'cooking' conditions in pulping digesters as undersized chips tend to be over-cooked, thus decreasing pulp yield and fibre strength, whereas over-sized chips are under-cooked (Tikka et al 1993;Hartler 1996;Hernández and Lessard 1997;Broderick et al 1998;Svedman et al 1998;Tessier et al 1999;Ding et al 2005;MacLeod 2007;Balakrishnan 2008;Clarke et al 2008; Dang and Nguyen 2008;Färlin 2008;Hellström 2010;Patt et al 2012;Cáceres et al 2015;Bäckström et al 2016).…”