Abstract: A method of treating ferromagnetic metal powder to achieve a uniform stable oxide coating is provided, comprising:(a) molding ferromagnetic metal powder into granules having a minimum diameter of 0.

Abstract: An apparatus for stabilizing treatment of ferromagnetic metal powder which apparatus makes it possible to form a surface-oxidized film on the powder which is as uniform and dense as possible and to afford ferromagnetic metal powder having a good quality, and which apparatus is characterized by comprising a horizontal, cylindrical, rotating type body of reactor; a feeding port for the ferromagnetic metal powder into the body; a withdrawing port for the ferromagnetic metal powder from the body; a blowing passageway for an oxidizing gas into the body; and a withdrawing passageway for the oxidizing gas from the body.

Abstract: A process for producing a ferromagnetic metal powder composed mainly of iron and having an oxidized coating and a superior dispersibility is provided, which process comprises feeding granules of a ferromagnetic metal powder composed mainly of iron and impregnated with an organic solvent into a horizontal, cylindrical, rotating type reactor having scraping plates fixed onto the inner wall thereof in parallel to the generating line thereof, passing an oxygen-containing gas through the reactor while rotating the reactor and keeping the inside temperature thereof at 10.degree. to 80.degree. C. to vaporize off the solvent and dry the granules, and then continuously or stepwise raising the temperature of the resulting material on heating while passing an oxygen-containing gas through the inside of the reactor.