Method of producing hydrated iron oxide

摘要

In a method of producing a hydrated iron oxide as a starting material for a magnetic powder by aging a suspension of a ferric hydroxide prepared by reacting a ferric salt with an aqueous solution of alkali, the aging temperature is controlled between 20 DEG and 100 DEG C. and pH is controlled between 1 and 6 for the first 5 to 240 minutes while nuclei of hydrated iron oxide crystals generate, and then the aqueous solution of alkali is added again to adjust the pH value to 10 to 13.5 to make the crystals grow. This production method is capable of producing an acicular hydrated iron oxide having a reduced particle-size distribution range and also capable of controlling the length of the crystals as desired.