One of the problems arising in the utilisation of high-yield pulps in papermaking is their tendency to produce various kinds of dissolved matter during mechanical treatment. One result of this is that the amount of paper producible from a given amount of wood is less than that which is calculated from the pulping yield. Moreover, the hazard element of the effluent from the environment aspect is increased.
The literature contains little discussion of this problem, although Sjbström et al. have observed the dissolution of xylan from birch pulps of both normal and high-yield. ⁽¹,²⁾
Within the framework of a project concerning the optimisation of the defibration and beating of high-yield pulps a study has been made of the material losses that occur during these process stages. The results of this study are presented in the following.