Optimization of the Prehydrolysis and Pulping Steps in ASAM Dissolving Pulp Production, 1994 Pulping Conference Proceedings
R. Patt, M. Zimmermann, O. Kordsachia, J. R. Hinck
The ASAM process has proven its capability to produce paper pulps with excellent properties. In this paper its potential to produce high-quality dissolving pulps is evaluated. Like in other alkaline pulping systems the production of ASAM dissolving pulps requires a prehydrolysis step. For beech, eucalyptus, spruce and pine this prehydrolysis step and the cooking stage were optimized.
For hardwoods water prehydrolysis results in better pulp qualities whereas for softwoods a prehydrolysis with weak sulfuric acid is more favorable. Withdrawal of the prehydrolysis liquor removes 70 – 80 % of the dissolved material from the chips. An additional washing increases the effectiveness of the cooking stage. If the prehydrolysis liquor is not withdrawn, the addition of methanol to the prehydrolysis liquor improves the results of hardwood pulping, except x-cellulose content.
Optimization of the Prehydrolysis and Pulping Steps in ASAM Dissolving Pulp Production, 1994 Pulping