Optimal Refining Strategy - Separate or Co-Refining? : Investigation using a 16' Double Disc Pilot Refiner

摘要

Results from pilot scale investigation of two refining strategies for a mixed furnish comprising bleached hardwood kraft short fibre and bleached softwood sulfite pulps using a 16" double disk refiner and at two different blend compositions are presented. The results show that an improvement in key strength properties of handsheets can be achieved if the pulps are co-refined at a lower refining intensity of 1.0 Ws/m, compared to separate refining of the short fibre and long fibre pulps at same applied net specific energy followed by blending. Strength development from co-refined pulp at higher refining intensity was found to be inferior to that of separate refining. Analyses of fibre length distribution and fibre morphology of the unrefined bleached sulfite long fibre pulp show that the characteristics of this pulp are much closer to a hardwood kraft short fibre than a typical softwood kraft pulp. The superior fibre development from co-refining of bleached hardwood kraft and bleached softwood sulfite pulps is likely due to the presence of excessive fibre debris or fines in the sulfite pulp. Separate refining of the sulfite pulp at 1.5 Ws/m refining intensity caused more fibre cutting than fibrillation.