Procédé de fabrication de l'oxyde de zinc pur ou du zinc métallique pur

28,188. StucklÚ, H. W. Baron de. Dec. 7, 1912, [Convention date]. Ammonium chloride, nitrate, sulphate, and sulphite. - A zinc-salt solution such as zinc chloride, nitrate, or sulphate is treated with ammonium sulphite in the presence of ammonia or ammonium carbonate, zinc sulphite being precipitated. The ammonia or ammonium carbonate may be produced by adding an alkali or alkaline-earth compound, such as calcium hydrate or sodium carbonate, to the ammonium sulphite. The ammonium sulphite is regenerated by absorbing sulphurous acid in neutral or slightly acid or slightly alkaline solution of ammonium sulphite obtained from the mother liquor, and then converting the bisulphite into sulphite by adding ammonia in a closed tank to avoid oxidation.