公开(公告)号：DE3246752A1

公开(公告)日：1984-06-20

申请号：DE3246752

申请日：1982-12-17

Applicant: MITSUI TOATSU CHEMICALS

Inventor： MATSUNAGA MITSUROU ,  MORITA ISAMU ,  FUKUDA NOBUHIRO

IPC: C01G49/02 ,  C01G49/06 ,  G11B5/706 ,  H01F1/11

Abstract: Process for producing goethite having an axial ratio of at least 7 and a specific surface area of 20-80 m /g, which is suitable for use in the production of alpha -iron powder, wherein an oxidising gas is intermittently introduced into a suspension of iron(II) hydroxide which has been obtained by reacting an iron(II) salt with an alkali metal hydroxide, the oxidation rate of iron(II) hydroxide being preferably controlled at less than 7% for each feed/feed stop cycle of the oxidising gas and, moreover, the duration of feeding the oxidising gas being selected to be inside 10 minutes and equal to or shorter than one quarter of the duration of the interruption of feeding in each of the individual feed/feed stop cycles of the oxidising gas.