Eucalypt cold soda pulping using a PFI mill

Cold soda pulping experiments were conducted using a PFI mill with a phosph or bronze tackle. The PFI mill was modified and fitted with torque transduc ers so that the reaction torque could be measured under load to allow the r efining energy to be determined. Preliminary trials showed that there were no latent properties in the pulps and confirmed that the ideal beating load was 3.33 N/mm. Comparison of dat a from the PFI mill and pilot-scale refiners including a Sunds Defibrator C D300 and an Andritz Sprout-Bauer 12-1 CP showed that certain pulp propertie s from young eucalypt plantation species did not correlate well, However, a good correlation was found between cold soda pulp properties of 8-year-old Eucalyptus nitens plantation species from the CD300 and a commercial cold caustic soda pulping plant. Further PFI mill trials were conducted to deter mine the effect of refining with a toothed brass sleeve insert to simulate a disc type refiner. Long refining times resulted in unrealistic energy con sumption. It was concluded that the PFI mill is an unsuitable small-scale substitute to replace pilot-scale disc refiners in the assessment of a pulpwood resour ce and the establishment of a species ranking system.