Recuperation of hydrochloric acid from spent metal pickling baths comprises addition of sulfuric acid, producing iron and zinc sulfates, and also zinc by addition of solvent

摘要

The recuperation of hydrochloric acid from spent metal pickling baths comprises t he addition of sulfuric acid to the bath, to produce iron and zinc sulfates and hydrochloric acid. Cooling of the resulting solution to ca. 0 deg. C precipitates ferrous sulfate heptahydrate by crystallization. Then, after vacuum evaporation, further cooling of the concentrate to ambient temperature solidifies the zinc sulfate and some of the ferrous sulfate. The zinc can also be separated by addition of solvent trapping the zinc salts.