Process for the preparation of acicular alpha -iron oxide hydrate

摘要

A process for the preparation of acicular alpha -iron oxide hydrate which comprises oxidizing a slurry of ferrous hydroxide having an excessive alkali concentration of 1.0 mol/l or above with an oxygen-containing gas, interrupting oxidation, adding an excessive quantity of an aqueous solution of a salt of aluminate, homogenizing and stirring the resulting mixture, again oxidizing it with an oxygen-containing gas to obtain a slurry containing free aluminate ion and alpha -iron oxide hydrate, homogenizing and stirring the slurry, then neutralizing and aging it, and washing and drying it.