| 摘要 |
PROBLEM TO BE SOLVED: To obtain a spindle shaped goethite particle uniform in particle size, free from the incorporation of a dendrite particle and the presence of particle aggregation by previously incorporating a specific compound in one of reaction solutions before the forming reaction of the goethite particle. SOLUTION: This spindle shaped goethite particle is produced by passing an oxygen-containing gas in a suspension having pH 8-11 and containing FeCO3 - or Fe-containing precipitate, which is obtained by the reaction of an alkali carbonate aq. solution or an alkali carbonate.alkali hydroxide aq. solution with a ferrous salt aq. solution, to oxidize. At this time, before the spindle- shaped goethite particle is formed, a carboxylic acid or the salt having chelating ability or further a 2-valent transition metal compound are previously incorporated in one or more solutions of the alkali aq. solution, the ferrous salt aq. solution and the suspension containing FeCO3 - or Fe-containing precipitate. The goethite particle has 0.05-0.25μm average major axis diameter and an average axial ratio of 4-10.
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