CONTINUOUS PRODUCTION OF IRON OXIDE HYDROXIDE

摘要

CONTINUOUS PRODUCTION OF IRON OXIDE HYDROXIDE In the production of an FeOOH seed suspension, comprising contacting an iron(II) salt solution with a basic precipitant to form a basic iron(II) salt or hydroxide suspension, oxidizing the salt or hydroxide, the precipitation and oxidation steps being carried out locally separate from one another and recovering a suspension of FeOOH, the improvement which comprises a) effecting the precipitation by mixing an about 1 to 20% by weight iron(II) salt solution with sufficient basic precipitant to precipitate about 25 to 95 atom % of the iron(II),b) at another location oxidizing 10 to 50% of the iron(II) precipitated in (a) over a period of from about 0.5 to 5 hours at a temperature in the range from about 20.degree.C to 65.degree.C,c) at another location oxidizing the suspension obtained in (b) with intensive mixing over a period of from about 0.01 to 1 hour to oxidize at least about 10% more iron until up to at most about 60% of the iron(II) precipitated in stage (a) is oxidized, andd) at another location substantially completely oxidizing the precipitated iron(II) still present over a period of from about 1 to 10 hours. Advantageously the temperature rises progressively from stage to stage. Immediately prior to stage (c) the suspension may be ripened for at least 30 minutes and, immediately after stage (c) it may be ripened for 30 minutes to 5 hours.