METHOD AND APPARATUS FOR RECOVERING PHOSPHORIC ACID FROM METAL ION-CONTAINING MIXED ACID AQUEOUS SOLUTION CONTAINING PHOSPHORIC ACID AND AT LEAST ONE KIND OF ACID EXCEPT PHOSPHORIC ACID

摘要

PROBLEM TO BE SOLVED: To provide a method and an apparatus for separating metal ions and recovering phosphoric acid at high yield from a mixed acid aqueous solution containing the metal ions such as a metal ion-containing mixed acid waste liquid produced from a metal etching process or the like in a semiconductor manufacturing plant or the like using a distillation and extraction means in place of a membrane or an ion exchange treatment which is commonly used as a conventional technique. SOLUTION: The method of recovering phosphoric acid from the metal ion-containing mixed acid aqueous solution containing the metal ions, phosphoric acid and at least one kind of the acid except phosphoric acid is carried out by (1) distilling the mixed acid aqueous solution to distill off the acid except phosphoric acid and water (containing no metal ion) and (2) extracting the metal ions under a condition that the metal ions are capable of being extracted from the remaining liquid containing phosphoric acid and water (containing the metal ions) to separate phosphoric acid of a lower layer and the metal ions of an upper layer respectively from each other. COPYRIGHT: (C)2007,JPO&INPIT