Examination of Separate and Mixed Refi ning Methods on Softwood and Hardwood Pulps for Linerboard Production

Abstract

The research focused on the study of process modifi cation of chemical pulp refi ning for a mixed treatment and separate methods for softwood and hardwood pulps in the production of linerboard. The study had the objectives to examine the effect of treatments on pulp quality, to fi nd out the optimum levels of pulp development and to examine their refi ning effi ciency. This study was carried out using a laboratory Valley beater and the pulp materials were obtained from linerboard manufacturers. The results showed that the separate and mixed refi ning methods produced different qualities of the fi nal blended pulp. In separate refi ning, the softwood pulp needed to be refi ned to a freeness of 500 mL and the hardwood pulp was required to be refi ned to a freeness of 320 mL, to obtain a superior strength of laboratory sheets. The wrong treatment of softwood and hardwood pulps produced severe degradation of the sheet quality. The treatment effi ciency using the laboratory device was not clearly differentiated between the methods. The results from the study could be applied to industrial refi ning as criteria to control the refi ning levels of pulp materials in separate refi ning, while the energy effi ciency could be further studied using a pilot refiner.