Process for regenerating an iron- and/or zinc-containing hydrochloric acid bath

摘要

Iron- and/or zinc-containing hydrochloric acid baths, such as are used especially in hot-galvanising installations, are to be regenerated without producing effluent. For this purpose, part quantities are intermittently removed from the bath, reprocessed by treatment processes taking place in the following order and returned to the bath. 1. Removal of part of the acid in a retardation unit with subsequent recycling into the acid bath together with metal fractions which have remained in the retardation unit when the bath fluid taken off was passed through. 2. Neutralisation of the withdrawn acid bath fluid leaving the retardation unit as effluent to pH > 7 with simultaneous precipitation and separation of the metals to be removed from the bath fluid. 3. Additional neutralisation and desalination of the effluent from the first neutralisation process. 4. Recycling of the effluent as circulating water into the acid bath by using it for backwashing the retardation unit.