Understanding the pulping and bleaching performances of eucalyptus woods affected by physiological disturbance

The wood quality is a factor of extreme importance when the pulping process is targeting high yield, low cost, and high pulp quality. Thus, wood knowledge is crucial for process optimization. In some northeastern Brazilian eucalyptus plantations, a physiological disturbance caused by water stress has been observed. Up to now, there have been no studies concerning the effects of such disturbances on the wood quality or on the pulping and bleaching process performance. The present work is aimed at understanding the impact of the stress on the production of bleached pulp. The wood quality of two clones (one tolerant to the disturbance and another sensitive), cultivated in sites where the disturbance is present and absent, was evaluated. Kraft pulps of kappa number 20 were produced and bleached by the sequence D-HT(EP)D-1 to a brightness of 90% ISO, which allowed for assessment of the wood pulpa-bility and bleachability. It was concluded that the disturbance affects the wood quality, and overall it showed a negative impact on the production of bleached eucalyptus kraft pulp, with significant potential economical setbacks. Application: This research is a case study of how bleached pulp production is affected by wood quality. Eucalyptus woods affected by physiological disturbances were studied, as well as their performance during kraft pulping and elemental chlorine-free (ECF) bleaching. Mills could use this information to better understand the wood consumption, chemicals, and energy demands on the process when using those woods in the pulp manufacturing.