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US 4,826,671 AGranted
Preparation of acicular .alpha.-Fe.sub.2 O.sub.3
AssigneeBASF SE
InventorsVolker Arndt, Rainer Feser, Werner Steck, Helmut Jakusch
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Abstract
Finely divided, acicular and pore-free .alpha.-Fe.sub.2 O.sub.3 is prepared from iron(III) salts in the presence of one or more organic substances which form complexes with iron(III) ions, in alkaline suspension, at from 80.degree. to 250.degree. C.
Claims3
A process for the preparation of acicular .alpha.-Fe.sub.2 O.sub.3 comprising
- precipitating iron(III) hydroxide from an aqueous solution of iron(III) salt in the presence of tin(IV) ions by adding an alkali metal hydroxide to an aqueous iron(III) salt solution containing from 10.sup.-3 to 2.10.sup.-2 mole of tin(IV) salt per mole of iron(III) salt,
- filtering off the resulting precipitate,
- suspending the precipitate in water to form an aqueous suspension of iron(III) hydroxide, and
- heating the aqueous suspension of iron(III) hydroxide at a temperature of from 80.degree. to 150.degree. C., at a pH of from 8.5 to 12, in the presence of an amount of at least one organic compound sufficient to form complexes with iron(III) ions whereby acicular .alpha.-Fe.sub.2 O.sub.3 is formed.
1 more element
Dependencies are inferred from the claim text.