| 摘要 |
PURPOSE:To obtain inexpensively high-purity iron oxide with a simple process by blowing further an O2-contg. gas to the filtrate obtd. by filtering off the precipitate formed by neutralizing a specific aq. iron salt soln. with an alkaline neutralizing agent and blowing an O2-contg. gas thereto. CONSTITUTION:The alkaline neutralizing agent such as NaOH is added to the aq. iron salt soln. contg. relatively much metallic salts except iron produced in a pickling stage for special steel or process for producing titanium so as to attain 0.5-2 degree of neutralization (2NaOH/Fe) to neutralize partly of fully the iron salt. The O2-contg. gas such as air is then blown thereto to settle Fe3O4 and the ferrite of the compsn. expressed by the formula (M is metallic elements except iron) at the same instant. The metals except iron are filtered off mostly as the precipitate and the filtrate having about <=1ppm impurity ion concn. is obtd. The alkaline neutralizing agent is added if necessary to such filtrate to adjust the degree of neutralization to 0.5-2 and the O2-contg. gas is blown thereto at 30-100 deg.C, by which the high-purity iron oxide (Fe3O4) is obtd.
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