| abstract |
A process for the production of pure tungsten and / or molybdic acid from alkaline tungsten and / or molybdenum metal salt solutions, which are contaminated in particular with silicon, phosphorus, arsenic ions etc., the solution being acidified, the precipitate formed then being filtered and tungsten and / or molybdic acid is produced from the pure solution by electrodialysis, which is characterized in that the adjustment of the pH value required for the precipitation of the hydrolyzing ions by admixing tungsten and / or molybdic acid which is alkali-free by means of cation exchange electrodialysis is carried out, a part of the tungsten and / or molybdic acid obtained after the electrodialysis being reused in the cleaning process. |