| 摘要 |
PURPOSE:To obtain goethite suitable for preparing gamma-Fe2O3 of high coercive force, by starting the oxidation reaction of a basic suspension containing iron (II) hydroxide, and continuing the reaction while adding the raw material to the system in the course of the reaction. CONSTITUTION:An aqueous solution of a ferrous salt, e.g. ferrous sulfate, is mixed with an alkali, e.g. NaOH, to prepare a basic suspension (pH: 12.5-13.8) consising of iron (II) hydroxide essentially. The suspension is then heated to 30-60 deg.C, and air is blown thereinto to start the oxidation reaction. The raw material is then partly added to the system. As for the raw material to be added, an aqueous solution consisting of iron (II) hydroxide essentially and/or an alkali or a suspension consisting of iron (II) hydroxide essentially is used. After the addition of the raw material, the oxidation reaction is continued to form a precipitate, which is washed with water, filtered and dried to give goethite powder in the form of fine needlelike crystal. |
