Process for obtaining ferric oxide and ammonium salts

Claim 1

Process for obtaining a pure finely divided ferric oxide which is suitable for use as a pigment and ammonium salts from an aqueous iron salt solution comprising the steps of: providing a reaction vessel; introducing a stream of ammonia gas into said reaction vessel; spraying an aqueous iron salt solution into said reaction vessel to form a dew or spray in the form of droplets in said reaction vessel, said aqueous iron salt solution comprising at least one iron salt selected from the group consisting of ferrous and ferric chlorides and sulphates and said aqueous iron salt solution having an iron salt concentration of at least 5% by weight; reacting said aqueous iron salt solution in the form of droplets with the ammonia gas in said reaction vessel to produce particles of an aggregate of ammonium salts and hydrated iron oxides, said ammonia gas being present in said reaction vessel in at least stoichiometric amount with respect to the iron salt in said aqueous iron salt solution; contacting said particles with a gaseous means comprising an oxidizing gas at a temperature not lower than the sublimation and/or decomposition temperature of the ammonium salts to oxidize and dry said particles thereby producing ferric oxide and sublimated ammonium salts; recovering said sublimated ammonium salts from said gaseous means; and recovering said ferric oxide.