| 摘要 |
813,457. Electrolytic fused salt baths; production of aluminium, titanium and zirconium. PECHINEY COMPAGNIE DE PRODUITS CHIMIQUES ET ELECTROMETALLURGIQUES. March 27, 1956 [March 30, 1955; July 6, 1955], No. 9546/56. Class 41. Oxygen-containing compounds present as impurities in chlorides and fluorides for use in chloride-fluoride electrolytic fused baths are converted into fluorides by treatment with a strong fluorinating agent, such as hydrogen fluoride, or an alkali metal, alkaline earth metal or ammonium bifluoride, e.g. at 200-600‹ C. A bath containing such impurities may be treated as such, but if chlorides which would be converted into undesirable fluorides are to be used in the bath, they are added in dry oxygen.- free form to the fluorinated other constituents. Thus for refining titanium and zirconium. using a bath of alkali metal and/or alkaline earth metal chlorides, the dry chlorides are mixed with 10 per cent ammonium bifluoride and heated to 300-500‹ C. part of the chlorides also being transformed into fluorides. In the production of aluminium using a chiolite-barium chloride bath, to avoid the production of undesirable barium fluoride, the periodic make-up additions of aluminium fluoride and of sodium and barium chlorides are treated separately. Thus the aluminium fluoride is mixed with ammonium bifluoride and heated at 400- 500‹ C. in a graphite crucible with steady stirring with an aluminium stirrer, and when bubbling has ceased the molten salt is cooled to near room temperature by pouring into an aluminium vessel, whereafter sodium and barium chlorides which have been thoroughly dried at 120 C. are added to it. |
