| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an inexpensive process of efficiently recovering rare earth oxides of high quality from waste grinding slurry containing rare earth elements. <P>SOLUTION: In a method of recovering rare earth elements, rare earth oxides are recovered from waste grinding slurry containing rare earth elements in a first process (I) including steps (1)-(5), and ammonium bicarbonate (precipitant) is reproduced and recycled in a second process (II) including steps (6)-(7). The process (I) comprises steps of: (1) mixing slurry containing rare earth oxides with oxidizing and reducing agents and acid, and heating and solving the slurry; (2) dissociating non-soluble components after adjusting the pH value of rare earth element solution; (3) adding ammonium bicarbonate to the solution to form rare earth carbonate; (4) dissociating the rare earth carbonate from the slurry; and (5) of baking the rare earth carbonate to recover it as rare earth oxides. The process (II) comprises steps of: (6) adding strong alkaline agent to a dissociated solution of rare earth carbonate to generate, condense and recover ammonium; and (7) bringing ammonium into contact with generated carbon dioxide to form ammonium bicarbonate solution and to recycle the welding as a precipitant for forming rare earth carbonates. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
