High Yield Pulping Process

Abstract

In view of high yield pulping, “vacuum impregnation two stage pulping process” which has a vacuum-impregnation stage proceeding a normal bisulfite cooking, was examined and compared with magnefite rapid vapor phase cooking process, modified magnefite process, polysulfide two stage cooking process and Stora two stage pulping processes.The results were as follows : vacuum impregnation two stage pulping process yielded the pulp which had the highest maximum screened yield among pulps examined. Owing to better impregnation effect of this process, the pulps were defibrilated with minimum removement of lignin, and in this process it was possible to cook with milder conditions as compared with that of other pulping processes.The pulps yielded with this process had somewhat lower strength properties. However, this process may have a great meanings in respect of the efficiency of wood utilization and suggest some other merits such as reduction of steam cost and chemicals even as compared with Stora Process.