Cellulose pulp prodn. from vegetable sources - with complete recycle of used lyes and washing water, to reduce pollution

摘要

Cooking lye based on soda is produced by SO2 treatment of a soln. formed of Na salts, opt. mixed with Ca, Mg and NH4 salts. Digestion is effected at pH 1.5-9.0. Cellulose fibres obtd. are sepd. from the used digestion lye which can be regenerated with SO2 satn. The fibres are subjected to O2 treatment in a alkaline medium, after which they are sepd. washed with water and pref. bleached, the used lye being recycled and made up with fresh base to form digestion lye. Pref. the washing water is recovered and made up to alkaline medium for O2 treatment by addn. of Na2CO3.