FIBER DEVELOPMENT IN CHEMIMECHANICAL PULP REFINING

A second-order PLS model has been calculated to study the impact of tw o-stage refining on the standard hand-sheet properties of a chemimecha nical pulp as well as the effect on fiber length distribution and whol e pulp specific surface. For a certain ratio of specific energy to ref ining intensity in the first stage, specific surface can be developed without loss in average fiber length. Fine material is peeled primaril y from the middle fiber fractions in the first stage of refining, when high energy levels are distributed over a large number of impacts. Wh ile increases in refining intensity may be substituted for increases i n applied energy to maintain adequate fiber length, whole pulp specifi c surface benefits most from higher energy levels applied at low inten sity. Minimizing energy requirements by increasing intensity in the fi rst refining stage is therefore better suited to the stiffer fibers co mmon to TMP pulping.