| 摘要 |
PURPOSE:To obtain a rare earth compd. having low content of Pb by adding alkaline earth metal ions to aq. soln. of a rear earth compd. in the presence of H2SO4 and removing separated precipitate of sulfate of the rear earth element. CONSTITUTION:H2SO4 and a water-soluble sulfate such as ammonium sulfate are added to an aq. soln. of a rear earth compd. cong. a Pb compd. as impurity (the concn. of the rare earth compd. is preferred to be ca. 0.01-1.5mol/l) and dissolved. Alkaline earth ions are added to the above-described aq. soln. cong. SO4 ion, and a sulfate of the alkaline earth element is precipitated. The coprecipitate derived from the Pb compd. in the above-described aq. soln. and above-described sulfate is separated and removed. By this method, a rare earth compd. contg. extremely small amt. of Pb compd. is obtd. easily without generating harmful gas.
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