RECOVERY OF WASTE HYDROCHLORIC ACID BY REMOVING IRON BY EXTRACTION

摘要

PURPOSE:To recover hydrochloric acid easily by diluting waste hydrochloric acid contg. Fe ion by adding a specified amt. of hydrochloric acid, oxidizing Fe2+ ion electrolytically to Fe3+ and removing the Fe3+ ion by extracting with an org. solvent, and using a part of the regenerated hydrochloric acid for the dilution of the waste hydrochloric acid. CONSTITUTION:Waste hydrochloric acid W produced in a pickling tank B and contg. =100g/l Fe ion is diluted with hydrochloric acid S contg. almost same concn. of total Cl- ion as the waste hydrochloric acid W, and adjusted hydrochloric acid P having =100g/l Fe ion concn. is obtd. Then, the hydrochloric acid P is fed to an anode chamber of an electrolytic cell T partitioned by a cation exchange membrane M, and Fe2+ ion is oxidized to Fe3+ ion by passing current through an anode A and a cathode C, then the waste hydrochloric acid is fed to an extraction stage 2 of the Fe ion where Fe3+ ion is extracted with an org. solvent [e.g. di-(2-ethyl hexy)phosphate]. The extracted hydrochloric acid is fed to a concentration adjusting stage 3 where regenerated hydrochloric acid I is produced by adding fresh hydrochloric acid H; a part of the regenerated hydrochloric acid I is used as hydrochloric acid S for dilution and the rest is recovered as recovered hydrochloric acid R which is reused in the pickling tank B.