Powder scraps of neodymium-iron-boron permanent magnet were deoxidized by using
calcium vapor, liquid or CaCl2 melt at 1223-1273K. Because the scraps
react with
the acidic solutions during leaching of the byproduct CaO, the methods for
removal of the excess amount of Ca and CaO were studied. When pH was controlled
at about 8 during several times leaching, the dissolution of rare earth elements
could be minimized. Ca vapor deoxidation could not supply enough amount of Ca
through CaO layer. When a large amount of CaCl2 was added, the
dissolution rate of CaO into the aqueous solution became faster, but some
amounts of rare earth components were lost. The deoxidation by Ca liquid and
5mass%CaCl2 and the subsequent leaching in distilled water with pH
larger than 8 gave the better result so that oxygen, even in heavily oxidized scraps, could be
lowered to 0.7 mass%.