Abstract: The invention relates to a process for the preparation of superazeotropic hydrochloric acid from metal chloride solutions, e.g. spent pickling solutions. The process is characterized in that the metal chloride solutions are thermally decomposed with the formation of a hydrochloric gas, that the hydrochloric gas is processed in a manner known per se into a superazeotropic mixture of hydrogen chloride and water, the superazeotropic gas mixture being condensed to yield a superazeotropic hydrochloric acid. The invention further relates to a process for ore and/or metal processing employing superazeotropic hydrochloric acid prepared according to the invention.

Abstract: The invention concerns a process for producing metal hydroxides with a small specific area in which the metal hydroxide is produced by hydrating a corresponding metal oxide and then treating it under pressure in an autoclave.

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.