Quality Types of Pine (Pinus sylvestris) Kraft Pulps and the Boundary Values of Their Kappa Numbers, Yield, and Reject Content in Digester Pulp

Abstract

Dependence curves for the kappa number of digester pulp (KN_DP), total pulp yield (TY), screened pulp yield (SY), and reject content in digester pulp (R_DP) as a function of the kappa number of screened pulp (KN_SP) were determined based on the results of several dozen kraft pulping tests of pine wood chips (Pinus sylvestris). These curves were then analyzed to assess whether their course could be used to distinguish qualitative types of pine kraft pulps and to determine the boundary values of the KN_DP, TY, SY, and R_DP indices for these types. Relationships of the form R_DP = f(KN_SP) were found to be particularly useful for this purpose. The identified types of pine kraft pulps and the limiting values of the parameters used to assess pulping process efficiency are presented in a table at the end of the paper.