A PROCESS FOR OBTAINING FERRIC OXIDE AND AMMONIUM SALTS, AND APPARATUS FOR CARRYING OUT SAID PROCESS

摘要

Ferric oxide and ammonium salts are prepared from aqueous iron salt solutions (e..g. liquid industrial waste) and from gaseous ammonia. In a reaction vessel (5) an iron salt containing aqueous solution (2) is reacted as a dew or spray with a NH3-stream (9). The amount of NH3 is at least stoichiometric in relation to the corresponding iron salts and free acid. After oxidizing and drying of the reaction product by oxidizing gases (3) and (4) at a temperature above the sublimation and/or decomposition temperature of the ammonium salt (pref. 350-600 DEG ), the ferric oxide is separated (14) and the ammonium salt is recovered by flash coding (27) in combination with an absorber washing column (19) and a crystallizer (11). In case of a vertical reaction vessel the gases are preferably horizontally and tangentially introduced to cause the formation of a cyclic movement of the gases. Suitable waste solutions are based on hydrochloric or sulfuric acid and contain iron chlorides and sulphates. The obtained ferric oxide is of the pigment type and has different shades of violet.