Partially Substituting MgO for NaOH as Alkali Source in the High-Consistency Retention Stage of P-RC APMP

摘要

In the conventional preconditioning followed by refiner chemical treatment, alkaline peroxide mechanical pulping (P-RC APMP) process, sodium hydroxide (NaOH) is used as the alkali source. In this study, magnesium oxide (MgO) was used to partially substitute for NaOH as the alkali source (substitution percentage of up to 50percent) in the high-consistency retention stage of the triploid poplar P-RC APMP process. The changes in pH values of the residual bleaching liquor, yields, and chemical components of the refined pulp in the high-consistency retention stage of the P-RC APMP process were investigated to explore the potential advantages of MgO instead of NaOH as the alkali source. The results showed that the partial MgO substitution for NaOH resulted in a lower pH of residual bleaching liquor and a higher bleached yield than those of the NaOH-based process. In addition, the dissolution of benzene alcohol extractives, lignin, pentosans, and carbohydrates were all decreased.