Method of reprocessing waste pickling liquors containing metal, nitric acid and hydrofluoric acid

摘要

The rolling or annealing (heat treatment) scale adhering to the surface of austenitic, austenitic-ferritic and ferritic steels is removed in pickling baths containing nitric acid and hydrofluoric acid. The metals present in the pickling solutions are recovered by the waste pickling liquor being introduced into a dialysis cell bounded by permselective membranes and arranged between a pair of electrodes whose anode and cathode space contains sulphur.