| 摘要 |
PURPOSE:To produce metallic iron powder of needle crystals having excellent magnetic characteristics by adding an aq. silicic acid soln. and ammonia to an aq. goethite suspension to prepare an alkaline suspension, adding an org. acid thereto, separating and drying the flocs produced by said addition, and reducing the flocs by heating in a reducing atmosphere. CONSTITUTION:An aq. silicic acid soln. and ammonia are added to an aq. goethite soln. to prepare an aq. goethite dispersion of 9.5-10.5pH. The goethite is contained at 2-6% concn. When an org. acid, for example, citric acid, oxalic acid or acetic acid is added to such aq. goethite dispersion to control its pH to 5-7, flocs are formed. The flocs are filtered and are dried at 120-125 deg.C. The dried flocs are reduced by heating to 400-600 deg.C in a reducing atmosphere. |
