METHOD FOR THE COMBINED PRODUCTION OF IRON (III) OXIDE FOR SOFT FERRITES, HARD FERRITES AND PIGMENTS

The method applies to the chemical industry for the production of ferric /III/ oxide for ferrites intended for electronics and for pigments used in construction clay products. High speed and capacity of ferric /III/ oxide production is achieved by this method. The method itself consists in exposing ferrous/II/ sulphate to oxidative hydrolysis at a temperature from 30 to 60 degrees C, blowing through a aqueous solution of ferrous/II/ sulphate oxygen-containing gas and adding simultaneously ammonia water to keep the pH of the suspension obtained within the limit 3.0-4.5, with subsequent filtering of the precipitate of ferric /III/ oxyhydroxide, sediment washing until reaching the absence of sulphate ions, drying and hardening at 700-800 degrees C. The oxidative hydrolysis for producing ferric /III/ oxide for soft ferrites and for hard ferrites is accomplished in the presence of manganous /II/ ions; when obtaining ferric /III/ oxide for soft ferrites, the oxidative hydrolysis is carried out at pH of 3.0-3.5 to 10-15 per cent oxidation of ferrous/II/ ions of the outlet ferrous/II/ sulphate to ferric /III/ ions and after separation of the precipitate from ferric /III/ oxyhydroxide for soft ferrites. The oxidative hydrolysis of the ferrous /II/ sulfate in the filtrate continues at a pH of 4.0-4.5 to 15-35 percent degree of oxidation of ferrous/II/ to ferric /III/ ions. After separation of ferric /III/ oxyhydroxide precipitate, intended for obtaining hard ferrites, ferric /III/ oxide is produced from the filtrate by the carbonate method.