Process for the preparation of isometric magnetic iron oxide

摘要

Isometric iron oxide pigments are prepared by an improved process by precipitation of aqueous solutions containing iron (II) salts with alkaline precipitating agents followed by oxidation of the precipitate at temperatures of from 20 DEG C. to 100 DEG C., wherein the improvement comprises adjusting the iron (III) content to 1 to 25 mol %, based on the total iron, before precipitation.