| 摘要 |
PURPOSE:To form magnetic ferrous oxide into fine grains as well as to imporove their needle-like property by a method wherein an alpha-FeOOH nucleus formation is performed under the presence of phosphorous acid or phosphite, and a dehydration by heating is conducted as possible in an inert gas atmosphere containing no oxygen. CONSTITUTION:A ferrous salt aqueous solution containing ferrous sulfate is partially neutralized using alcali, and the Fe component contained in said solution is partially formed into alpha-FeOOH crystal by peforming an oxidation treatment. At this time, the Fe density of a ferrous sulfate solution is ordinarily established at 30g/l-100g/l. On the stage of nucleus formation, the ordinary range of reaction temperature is 30-55 deg.C. pH is maintained between 3 and 8 in general. The solution, with which nucleus forming reaction has been finished, is oxidized and crystal nucleus is grown while alcali is added under the presence of phosphorous acid or phosphite. Then, the obtained dehydrate is formed into magnetic ferrous oxide with oxidation degree 1.33<=X<=1.50, by reducing it using hydrogen or by performing an additional oxidization process. |
