Burned wood in the pulp and paper industry: A literature review

Abstract

Fires play an integral part in Canadian forest architecture. Low-value wood, from burned stems, is an important source of fibre for the pulp and paper industry. Although wood chemistry changes induced by fire are substantial, burned stems exhibit a demarcation layer between the char and undamaged wood which is only a few cells thick. The loss of stem moisture content requires that burned wood is processed within one year. Aggressive debarking will minimize charcoal contamination and careful metering of chips from burned wood into any pulping process is essential. Chips with low moisture content must be pre-steamed prior to kraft cooking, and chemical pre-treatment may improve mechanical pulp quality.Key words: burn intensity, wood chemistry, charring, stem moisture content, charcoal contamination, chip metering Les feux de forêt sont un élément intégral de l'architecture de la forêt canadienne. Le bois de faible valeur tiré des tiges brûlées constitue une source de fibre pour l'industrie des pâtes et papier. Même si les modifications de la chimie du bois provoquées par le feu sont substantielles, les tiges brûlées exhibent une couche de démarcation entre le bois calciné et le bois sain qui n'est que de quelques cellules d'épaisseur. La perte de l'humidité contenue dans la tige entraîne l'obligation de transformer le bois brûlé en moins d'un an. Un écorçage plus intense minimisera la contamination par des particules brûlées et un dosage soigné des copeaux provenant de tiges brûlées au cours du processus de mise en pâte est essentiel. Les copeaux de faible niveau d'humidité doivent subir un traitement à la vapeur avant une cuisson selon le procédé kraft et un pré-traitement chimique peut améliorer la qualité mécanique de la pâte.

Salvage logging in the boreal and cordilleran forests of Canada: Integrating industrial and ecological concerns in management plans

“…Fire by itself thus causes minimal losses, only 3% to 4% of standing volume, and occurring mostly in small-diameter, low-value trees (Lowell et al 1992). Although the charcoal associated with the chemically altered outer layers can cause problems in further treatment of the timber, aggressive debarking is usually sufficient to minimize charcoal contamination (Watson and Potter 2004). Subsequently, the degradation that follows the actual fire is a continuous process that can lead to significant losses in standing volume depending on the timing of salvage operations.…”

“…Pulp produced with such low-moisture chips usually shows some deleterious effects: low production rates, lower pulp brightness or reduced pulp viscosity. Chip water content can be increased by pre-steaming or by mixing them with green chips, but below a given percentage of water content, chip rewetting can be very difficult, and deleterious effects are unavoidable (Watson and Potter 2004). Since stem moisture decreases at a constant rate following the death of the tree, the best option to preserve pulp quality is thus to harvest fire-killed trees within 1 year following disturbance.…”

“…However, wood decay diminishes the potential of salvaged pulpwood as the degradation of structural polysaccharides decreases fibre length and thus the quality of the final product (Wright et al 1956). Charcoal contamination can represent a problem in pulp production and a series of measures must be applied to reduce its effects (Watson and Potter 2004 equipped with modified tips to aggressively remove charred portions of the logs (Araki 2002). Water-blasting has also been used to maximize charcoal removal (Watson and Potter 2004).…”

“…Charcoal contamination can represent a problem in pulp production and a series of measures must be applied to reduce its effects (Watson and Potter 2004 equipped with modified tips to aggressively remove charred portions of the logs (Araki 2002). Water-blasting has also been used to maximize charcoal removal (Watson and Potter 2004). All of these measures increase processing costs and make difficult the simultaneous treatment of burned and green logs.…”

Moisture and energy content of fire-burnt trees for bioenergy production: A case study of four tree species from northwestern Ontario

“…Although there have been concerns over the effects of salvage logging residues from the natural ecosystem (Nappi et al 2004), the current forest management regime in Ontario has encouraged the utilization of fired killed and damaged trees (OMNR 2002). While temperature does affect the properties of wood (Kolin andDanon 1998, Winandy andRowell 2005), mild wildfires only affect the outer part of trees (Watson and Potter 2004). The insulating nature of the bark and wood as well as relatively short exposure to the fire limits the damage to the remaining wood (Zicherman andWilliamson 1981, Bortoletto andMoreschi 2003).…”