Effect of Modified Cooking on Eucalyptus globulus and Eucalyptus nitens

Rudine Antes

Research output: ThesisDoctoral ThesisCollection of Articles


The objective of this work is to evaluate how Eucalyptus globulus and Eucalyptus nitens wood raw materials perform in modified cooking: SuperBatch™ (SB), CompactCooking™ (CC) and Lo-Solids™ (LS). Modified cooking methods have been developed to improve kraft cooking yield, chemical and energy consumption, bleachability and paper's technical properties. The SB cooking technology needed a 20–30 units higher H-Factor than CC and LS to reach the same degree of delignification for both raw materials. The highest screened cooking yields were obtained from conventional batch cooking with E. globulus (approximately +1%), and the lowest from batch cooking with E. nitens (approximately -0.5%). For both species, the CC technology tended to produce unbleached pulps with a higher intrinsic viscosity (20–50 ml/g). The LS technology produced fibers with the highest fiber wall thickness and fiber saturation point (FSP) values. Modified cooking methods did not affect the water retention value (WRV); however, the different raw materials responded differently. E. nitens pulps presented 0.15 g/g higher WRVs for both bleached and unbleached pulps than E. globulus pulps. In terms of fiber surface composition, no differences could be attributed to modified cooking methods. The total charge of fibers after LS cooking was slightly higher (~10–20 mmol/kg) compared to that of fibers after the other cooking methods. From the results, it can be concluded that the modified cooking methods (SB, CC and LS) with a slightly different cooking chemistry do not contribute significantly to yield and other cooking parameters. The differences seen in mill environment within the modified cooking technologies can be attributed to the equipment design, wood column movement and alkali distribution within the column and control systems. The decision on selection of the technology to produce pulp from E. globulus and E. nitens has to be made based on other than cooking chemistry, rather operation parameters that improve mill process control and runnability of the pulp mill. These parameters are e.g. control and stability of chip feed, liquor to wood ratio and chip column movement. In addition, one can conclude that the main differences in the paper technical properties and fiber characteristics come from differences in fiber cell wall structures between the wood species and mechanical effects of the applied modified cooking technology. The results show that the industrial process conditions such as temperature, alkali charge, free and bound liquor gradients have more important impact than cooking chemistry itself on the pulping and pulp quality.
Translated title of the contributionEffect of Modified Cooking on Eucalyptus globulus and Eucalyptus nitens
Original languageEnglish
QualificationDoctor's degree
Awarding Institution
  • Aalto University
  • Sixta, Herbert, Supervising Professor
  • Joutsimo, Olli, Thesis Advisor
Print ISBNs978-952-60-7603-4
Electronic ISBNs978-952-60-7602-7
Publication statusPublished - 2017
MoE publication typeG5 Doctoral dissertation (article)


  • Eucalyptus globulus
  • Eucalyptus nitens
  • modified cooking
  • CompactCooking
  • SuperBatch
  • LoSolids
  • chemical composition
  • fiber cell wall structure
  • fiber surface
  • bleachability

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