Lo-Solids Kraft Pulping off Eucalyptus Wood, 2007 Engineering, Pulping & Environmental Conference

Please Note: This document will be available in PDF format in the "My Electronic Documents" link on the home page once your order has been completed. Please make sure you have the latest version of Acrobat Reader. Click on the Acrobat Reader icon to check for the latest version, it’s FREE. To print a hardcopy of a PDF file correctly you must have a postscript printer. If you are not sure if your printer is a postscript printer please refer to your owner’s manual.

The objective of this study was to evaluate the behavior of eucalyptus wood chemical components during Lo-Solids kraft cooking. All cooks were carried out in duplicate to obtain pulp of 16 ± 0.5 kappa number. Semi-delignified chips, pulp and cooking liquors were collected from five different zones of a laboratory digester. Wood delignification (97%) occurred in five phases with the “bulk delignification” made up of three steps. Overall, 14.2% of the cellulose and 53.9% of the hemicelluloses were removed at the end of the cook. Lignin richer in guaiacyl units was removed during the impregnation while during bulk delignification the lignin removed was progressively richer in syringyl units. There was a rapid formation of hexenuronic acids in the “Impregnation Zone” but their concentration decreased toward the middle of the “Upper Cooking Zone” and from this point on they increased until the end of cook. Solids content and alkali concentration in cooking liquor were relatively constant during the whole cook. A large viscosity drop (31.8 cP) occurred during the final cooking phase, despite the small yield loss (1%) coupled to a considerable kappa reduction (5.5 units).