Process for the selective removal of ferric ion from an aqueous solution containing ferric and other metal ions

摘要

A process for treating an aqueous acidic solution containing a large amount of ferric ion and other metal ions such as a hydrochloric acid solution of manganese nodules, which includes contacting the aqueous solution with an organic extractant to selectively extract the ferric ion therefrom. The extractant is comprised of a dialkylphosphoric acid having 6-12 carbon atoms and a hydrocarbon solvent such as kerosene. The aqueous phase obtained after the extraction is then added with a pH-controlling agent to increase the pH thereof to a value so that unextracted ferric ion remaining therein may precipitate as ferric hydroxide while the other metal ions may be prevented from precipitating. Solid-liquid separation of the resulting mixture gives a solution having a ferric ion concentration of about 0.1 g/l or less. The pH-controlling agent is preferably an industrial waste containing a metal oxide or hydroxide such as a sludge from plating industries. By repeating the above procedure, a substantially ferric ion-free solution may be obtained.