| 摘要 |
PURPOSE:To produce the titled highly dispersed powder of single particles having a narrow particle size distribution, by heat-treating a suspension of iron alpha-oxyhydroxide particulate powder obtained by a specific production process, reading an aqueous solution of a ferrous salt and reoxidizing the resultant suspension. CONSTITUTION:An aqueous solution of a ferrous salt, e.g. aqueous solution of ferrous sulfate, etc., is mixed and stirred with an aqueous solution of an alkali, e.g. aqueous solution of caustic soda, etc., at >=1.5 alkali equivalent ratio to the ferrous salt and the resultant mixture is subjected to oxidative reaction with an oxygen-containing gas. The obtained suspension of iron alpha- oxyhydroxide particulate powder is directly heat-treated at a temperature as high as 60-100 deg.C. An aqueous solution of a ferrous salt at 0.5-10% atomic and molecular ratio [Fe(II)/alpha-FeOOH] based on the iron alpha-oxyhydroxide in the suspension is then added thereto to carry out oxidative reaction with the oxygen-containing gas again and afford the aimed needle-like iron alpha- oxyhydroxide powder of highly dispersed single particles having a narrow particle size distribution with hardly any mixed dendritic particles or fine particles.
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