Method for preparing Nd-Fe-B based rare earth sintered magnet

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The present invention relates to a method for manufacturing a sintered magnet made of Nd-Fe-B-based rare earth. The method for manufacturing the sintered magnet comprises a step of heat-treating scrap and waste magnets in the inert gas atmosphere; a step of cooling the heat-treated scrap and waste magnets, and injecting hydrogen gas into the scrap and waste magnets to treat the scrap and waste magnets; a step of treating the scrap and waste magnets, which are treated by the hydrogen gas, by inert gas; a step of obtaining a synthetic powder by cooling the scrap and waste magnets which are treated by the inert gas; and a step of sintering the synthetic powder. According to the present invention, the manufacturing method is capable of manufacturing an Nd-based sintered magnet with low magnetic properties at low cost by using the waste magnets and sintered magnet scrap as material powder. The Nd-based sintered magnet manufactured by the method is applied to a pulling magnet for a hard disk, a speaker and a vibrating magnet for a smart phone, and a speaker for a car, and has an effect of lowering the prices of existing products.(AA) Hydrogen gas treatment(BB) Three-phase decomposition(CC) Argon gas treatmentCOPYRIGHT KIPO 2014