Impact of Eucalyptus Bark Contamination during Pulping of Mixed Southern Hardwoods

摘要

The use of eucalyptus as a partial replacement for mixed southern hardwoods can result in significant amount of eucalyptus bark being incorporated into the accepted chips going to the digester. When eucalyptus is first harvested, the bark peels off in large sheets which will pass through the southern hardwood designed chipper. After being cut for more than about 4-6 weeks, the bark tightens onto the bole of the tree and again passes through the non- eucalyptus designed chipper. As a result, significant quantities of eucalyptus bark may end up being incorporated into the chips going to the digester. In this study, the impact of pulping eucalyptus bark has been examined in the laboratory. A series of control studies were performed with mixed southern hardwood bark. Incorporating bark into the cook results in increased kappa number, decreased pulp yield, and increased alkali consumption. If the percent applied AA is increased to counter the increased alkali consumption, increased HexA generation results.