METHOD FOR PRODUCING RARE EARTH-IRON-NITROGEN BASED MAGNET FINE POWDER

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PROBLEM TO BE SOLVED : To provide a method for producing rare earth-iron-nitrogen based magnet fine powder where the conventional method for nitriding rare earth-iron based alloy powder is improved, so as to obtain a rare earth-iron-nitrogen based magnet having high magnetic properties. SOLUTION : Rare earth oxide powder, iron powder, and at least one kind of reducer powder selected from alkali metal, alkaline-earth metal and their hydrides are mixed in a prescribed ratio, the obtained mixture is heated at 900 to 1, 180°C in an inert gas atmosphere, hydrogen is absorbed in the obtained reaction product, so as to be collapsed, thereafter, the collapsed reaction product is subjected to nitriding treatment and wet treatment, and the wet-treated magnet coarse powder is subjected to heating treatment, and is pulverized, so as to produce rare earth-iron-nitrogen based magnet fine powder. At this time, using a rotary kiln in the nitriding treatment process, as the gaseous mixture comprising ammonia and hydrogen is made to flow into the rotary kiln, the collapsed reaction product is fed into the rotary kiln together with an almost spherical pulverized medium. COPYRIGHT : (C)2008, JPO&INPIT