Fundamental Attributes as a Basis for Selection of a Wood Chip Size Classification Series, 1994 Pulping Conference Proceedings

W. K. Sacia, G. R. Marrs

Several alternatives for a wood chip size classification series have gained relatively wide acceptance in the pulp and paper industry. Selection of a screening size series should be based upon fundamental attributes—thus a kraft pulping study was performed. Northern Boreal softwood chips were classified by an extensive series of commonly used round hole and thickness size classes to determine which gave more useful information about chip quality. The results indicate that, as previously reported in the literature, oversize chips are best defined by thickness classification. Chip fines are better defined by a –3 mm round hole criteria than by a –3/16” round hoe criteria, based on yield and fiber length results. Alternative pin chip definitions (round hole vs. slots) had no detectable differences in yield, but displayed a slight differentiation based on fiber length, for the Stalsvets (-7 mm, +3 mm round hole) definition. The correlation of classification results between different methods is also discussed.