SEPARATION OF SULPHIDES AND CHLORIDES FROM PULPING LIQUORS BY ELECTRODIALYSIS

摘要

A process using an electrodialysis system employing cation-selective membranes and anion-selective membranes, particularly monovalent anion-selective membranes, is used to separate kraft pulping liquors into two streams; one that is rich in sulphides (to be used in the initial stage of pulping), and another that is poor in sulphides (to be used in the final stage of pulping). By separating pulping liquors in this way, the sulphur balance in the kraft process can be maintained while obtaining the benefits of modified pulping. The same electrodialytic system can be used to separate green and polysulphide liquors into sulphide-rich and sulphide-poor components.