Patent ID: 9315392
Filing Date: 2016-04-19
CPC Classification: C01G,C01P,H01F

Claim Text:
1. A method for preparing magnetic iron oxide Fe 21.333 O 32 , comprising the following steps: (1) preparing a ferrous salt solution with solid soluble ferrous salt; (2) preparing a hydroxide solution; (3) mixing said hydroxide solution and said ferrous salt solution in a co-current manner for reaction, controlling said hydroxide solution and said ferrous salt solution at an alkali ratio of 0.6-0.8, controlling said ferrous salt solution at a feeding speed of 200-300 ml/min, and said hydroxide solution at a feeding speed of 50-60 ml/min, and controlling the reaction temperature not exceeding 30° C.; (4) after the reaction in step (3) is finished, yielding a first mixture, charging the first mixture with a gas containing oxygen for oxidation, and controlling the first mixture at a pH value of 6-8 until the oxidation is finished to yield a second mixture; (5) filtering, washing with water and drying said second mixture to yield a precursor; and (6) calcining the precursor obtained in step (5) at 250-400° C.