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AssigneeDeutsche Gold- und Silber-Scheideanstalt vormals Roessler
InventorsHelmut Reinhardt, Everhard Gratzfeld, Eva Clausen
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Ferrocyanide blue is produced by reacting an aqueous ferrocyanide solution with an iron II salt and subsequently aging of the precipitate at elevated temperature and optionally at elevated pressure as well as oxidation in acid medium. The improvement comprises simultaneously leading the aqueous solution of ferrocyanide and the ferrous salt solution into a water receiver, whereby optimum mixing occurs during the precipitation and whereupon the precipitate formed, the so-called white stage is aged in known manner directly in the reaction medium in the presence of the salts formed in the reaction at elevated temperature and optionally under pressure and likewise in known manner is converted into Berlin blue by oxidation in acid medium.
In a process for the production of ferrocyanide blue by reaction of an aqueous ferrocyanide solution with an iron II salt and thereafter aging the precipitate at elevated temperature and oxidizing the aged precipitate to form ferrocyanide blue, the improvement comprising simultaneously introducing an aqueous solution of ferrocyanide consisting of a mixture of sodium and potassium ferrocyanides and an aqueous solution of the ferrous II salt into a water receiver containing water in an amount of 20 to 40 weight % based on the weight of the entire suspension formed to thereby provide optimum mixing and to form a suspension of the precipitate of ferrocyanide white in the resulting aqueous reaction medium, and aging the precipitate in the reaction medium in the presence of the salts formed in the reaction.
Dependencies are inferred from the claim text.