Abstract: A metallic magnetic powder as fine metallic particles is produced by adsorbing zinc ion on iron oxyhydroxide in a alkaline bath with heating during or after the adsorption and then reducing it.

Abstract: A magnetic powder is produced by mixing an aqueous solution of a metal salt with an aqueous solution of a reducing agent such as sodium boron hydride in a magnetic field to reduce said metal salt to continuously form a magnetic powder and heat-treating said magnetic powder in a non-oxidative atmosphere. The aqueous solution of a metal salt is mixed with said aqueous solution of a reducing agent in a magnetic field to continuously discharge a reaction mixture containing a magnetic powder having pH of 2.5 or lower from a reactor and said reaction mixture containing said magnetic powder is immediately continuously washed and filtered and said magnetic powder is heat-treated in said non-oxidative atmosphere.

Abstract: A master magnetic recording medium comprises a polymer film substrate coated with a magnetic layer comprising a binder, a metallic magnetic powder A obtained by a wet reduction and a metallic magnetic powder B obtained by a dry reduction wherein both said magnetic powders A and B have each coercive force of 1800 Oe or higher and each saturated magnetization .sigma.s of 130 emu/g. or higher and a ratio of said magnetic powder A to said magnetic powder B is in a range of 0.1 to 10 by weight.

Abstract: A magnetic powder is prepared by dispersing iron oxide or iron oxide hydrate which can be coated or doped with at least one of cobalt, nickel, tin, titanium, bismuth, zinc or antimony or its compound, as the starting material into an aqueous solution of a water soluble resin and separating the powder and heating it in a reducing atmosphere to reduce it.