METHOD FOR ELECTRODIALYSIS-TREATING NITRIC ACID AND HYDROFLUORIC ACID WASHING WASTE LIQUID AND DEVICE THEREFOR

摘要

PURPOSE: To make a current efficiency of metal ion recovering high and execute electrodialysis at low power consumption unit by using a four-chamber type electrolytic cell having two intermediate chambers in which each electrode chamber and intermediate chamber are isolated with a cation exchange membrane and two intermediate chambers are isolated with an anion exchange membrane. ;CONSTITUTION: This devise is composed of an anode chamber 24, the first intermediate chamber 25, the second intermediate chamber 26 and a cathode chamber 27, and the chamber 24 and the chamber 25, and the chamber 26 and the chamber 27 are separated respectively with anion exchange membranes 28 and 30, and the chamber 25 and the chamber 26 are separated respectively with cation exchange membranes 29. Moreover, the waste is subjected to electrodialysis by the electrolytic cell housing (a) a sulfuric acid and/or nitric acid- -containing aq. soln. in the chamber 24 as an anolyte, (b) a mixed aq. soln. of nitric acid and hydrofluoric acid in the chamber 25 as the first intermediate liq., (c) a nitric acid and hydrofluoric acid washing waste liq. containing a metallic ion consisting essentially of iron ion in the chamber 26 as the second intermediate liq. and (d) an aq. soln. containing inorg. salt and a pH buffering agent in the chamber 27 as a catholyte to recover a part of the first intermediate liq. as the nitric acid and hydrofluoric acid and the metallic ion in the second intermediate liq. is reduced and removed and a part is abandoned.;COPYRIGHT: (C)1996,JPO