USING SOLID-PHASE EXTRACTION TO ASSESS WHY ASPEN CAUSES MORE PITCH PROBLEMS THAN SOFTWOODS IN KRAFT PULPING

The Prince Albert pulp and paper mill makes aspen and softwood kraft p ulps, alternating on one production line. This helps to control pitch problems, which are more severe with aspen, particularly when unseason ed chips are pulped. We analyzed the extractives contents of fresh log s, seasoned and unseasoned aspen chips, and never-dried aspen and soft wood pulps at the brown decker and after bleaching. The characterizati on included total acetone extractives and different lipid classes frac tionated by solid-phase extraction (SPE). The softwoods contained at l east as much or more extractives as aspen, confirming that total extra ctives cannot be used as an index for predicting pitch problems. The r esults from solid-phase extraction show that for aspen, the sterol est ers/waxes fractions were high in wood and pulp. Triglycerides in the a spen pulp fro the brown decker were only slightly reduced by the bleac hing sequence. Natural seasoning decreased triglycerides and sterol es ters/waxes contents; however, chip brightness also decreased.