Process of preparing superfine ferroferric oxide particle

The present invention is preparation process of superfine ferroferric oxide particle. Unlike available superfine ferroferric oxide particle preparing process, which mixes trivalent iron salt and divalent iron salt in certain ratio under the protection of N2 gas directly and has complicated operation and hard control, the present invention features that superfine ferroferric oxide particle is prepared by means of the reduction of iron powder and the oxidation of trivalent iron salt and the preparation process needs no N2 gas protection and is easy to control. The prepared superfine particle may be used in paint, ink, stealth material, magnetic record and other fields and as the important part of magnetic fluid, gas sensitive and humidity sensitive material.