Eucalyptus Wood Quality and its Impact on Kraft Pulp Production and Utilization

摘要

This paper summarizes our research findings over the last five-years on eucalyptus wood attributes and their impact on process efficiency and pulp utilization,addressing the influence of species and harvesting age.It is concluded that efficient production of kraft pulp is achieved with eucalyptus wood having reasonably high density,low extractives and lignin quantities,high lignin S/G ratio and high xylans and uronic acids contents.Woods containing high quantities of lignin tend to possess lignin of low S/G ratios and are hard to process.Age significantly affects wood chemistry and morphology and its behavior in kraft pulping and pulp use.Wood density,extractives content and fiber coarseness increase with age.Pulping yield increases with wood age for some eucalyptus species but the opposite is observed for others.Eucalyptus hemicelluloses are mainly comprised of a xylan unusually rich in uronic acids,which is reasonably stable towards kraft pulping.The xylans retained in the kraft pulp substantially improve their refinability.The increase in wood age and density increase fiber coarseness,which negatively affects pulp refinability but increases its drainability.