Hydrated iron oxide prodn., useful as magnetic oxide intermediate - by adding ferrous salt soln. or hydroxide suspension to alkaline suspension during oxidn.

摘要

In the prodn. of a hydrated Fe oxide (I) with goethite as main component by oxidn. of an alkaline suspension based on Fe(OH)2, which is prepd. by mixing a base with an aq. soln. of a Fe(II) salt, an aq. soln. of a Fe(II) salt, with or without a base, or an aq. suspension of Fe(OH)2 is added after the start of oxidn. and oxidn. is continued. Pref. oxidn. is carried out by injecting air bubbles and/or adding an oxidant (H2O2, NaClO3, KClO3, NaNO3, KNO3). The Fe(II) salt soln. or FE(OH)2 suspension is added gradually and continuously. (I) is used in the prodn. of magnetic Fe oxide with high coercivity. The continuous method of prodn. can give a prod. yielding gamma-Fe2O3 with higher coercivity, e.g. 480 Oe or higher.