Method for recovery of reusable chemicals from C10.sub.2 generator effluent

摘要

Method for the recovery of acidic effluent from pulp mill chlorine dioxide generators using the Mathieson or Solvay system. The spent generator acid is directed through a three-stage evaporation/crystallization process in which spent acid from the generator is evaporated and crystallized to produce stage 1 sodium bisulfate crystals. The first stage crystals are then redissolved to form a second solution which is crystallized in order to yield stage 2 sodium sesquisulfate crystals and, finally, the second stage crystals are redissolved in a third stage evaporation/crystallization stage to yield sodium sulfate crystals. Besides salt cake, the system also produces reusable sulfuric acid for the chlorine dioxide generator. No chemicals are added during the recovery steps.