Abstract: A method and a device (13) are disclosed for the electrolytic pickling of flat metal products (2), in particular special steel and/or carbon steel strips. At least one diamond electrode and/or at least one lead/tin electrode, for example a lead 93/tin7 electrode (15) is used. The special characteristic of the diamond electrodes and/or lead/tin electrodes is the form of water replacement. Whereas in electrolysis water is usually split into hydrogen and oxygen, the diamond electrode and/or lead tin electrode provides a working range in which ozone or highly reactive hydroxyl radicals are formed instead of oxygen. As a result the pickling times are significantly reduced in comparison to the conventional chemical descaling, and also in comparison to the conventional electrolytic pickling.

Abstract: During the pickling, etching, chemical shaping etc. of steels, stainless steels, special alloys and special metals and the dissolution of those metals, metalliferous solutions of the acids employed arise in the course of such processes which must either be disposed of by neutralization or be used for the recovery of the acids and metals by expensive processes. According to the invention the production or recovery of nitric acid or a mixture of nitric acid and hydrofluoric acid takes place by spray-roasting the solutions at temperatures of 200.degree. to 500.degree. in a reactor (1) and subsequent absorptions or condensation of the gases generated in column means (7, 8) at temperatures of 0.degree. to 70.degree. C.