| 摘要 |
PURPOSE:To make a high-concn. reaction possible and to obtain the fusiform magnetic particulate powder having a large axial ratio while saving resources and energy by ageing an Fe2O3 suspension formed in an aq. mixed soln. of an alkali carbonate and an alkali hydroxide, and then oxidizing the suspension with air in the presence of a zinc compd. CONSTITUTION:An aq. soln. of a ferrous salt is allowed to react with the mixed soln. (e.g. 1.2-2.5 equivalents in total based on Fe<2+>) of an aq. alkali carbonate soln. and 1-50% aq. alkali hydroxide soln. to form an Fe2CO3 suspension. In this case, a zinc compd. such as ZnSO4 is added to either the raw material soln. or the suspension (0.3-10.0 atom%, or preferably 0.5-8.0atom%, of the compd. expressed in terms of Zn is added based on the Fe in the aq. ferrous salt soln.). The suspension is then aged at 30-60 deg.C for 10-100min in a nonoxidizing atmosphere, an oxygen contg. gas such as air is passed through the suspension to oxidize the compd., and fusiform goethite magnetic particulate powder is obtained. |
