| 摘要 |
<p>PROBLEM TO BE SOLVED: To separate and extract rare-earth metal ions from an aq. soln. contg. at least 2 kinds of the ions with a high selectivity and extraction rate by regulating a pH value so that the pH value after solvent extraction is above a specified value. SOLUTION: A raw aq. soln. to be applied contains at least 2 kinds of rare- earth metal ions selected from Pr, Nd, Y and Er. An extraction reagent PIA-8 to be used for extraction is diluted in a nonaqueous org. solvent as it is used for ordinary solvent extraction. The pH value at the time of extracting is regulated so that the pH value is to >=3, preferably 3-3.5, after solvent extraction. A mineral acid or an aq. alkaline soln. is previously added to the raw aq/soln. so that the pH value is regulated to the desired pH value. An aq. soln. of the hydroxide and/or carbonate of ammonium and such an alkali metal as Na and K is exemplified as the aq. alkaline soln. and hydrochloric acid, nitric acid, sulfuric acid, etc., are exemplified as the mineral acid.</p> |
