Method for recovering the removed phosphoric acid nitric acid and dissolved metals from phosphoric acid-based mixed acid waste

摘要

PPROBLEM TO BE SOLVED: To provide a method for recovering phosphoric acid by which high-purity phosphoric acid can be separated and recovered by removing nitric acid and metals from a phosphoric acid-based mixed acid waste liquid. PSOLUTION: The method for recovering phosphoric acid includes: a nitric acid extraction step wherein a mixed acid waste liquid containing nitric acid, phosphoric acid and metals is mixed with a first extractant solution containing a trialkyl phosphate to extract the nitric acid by selective dissolution in the first extractant solution; a metal extraction step wherein phosphoric acid-containing extraction residual liquid of an aqueous phase discharged from the nitric acid extraction step is mixed with a second extractant solution containing an acidic phosphoric ester to extract the metals by dissolution in the second extractant solution; and a step of recovering the phosphoric acid from phosphoric acid-containing extraction residual liquid of an aqueous phase discharged from the metal extraction step. PCOPYRIGHT: (C)2010,JPO&INPIT