Method for purifying scandium and scandium extractant

Abstract

Provided is a method for efficiently purifying scandium by separating scandium and impurities from an acidic solution which contains scandium and impurities that include iron. A method for purifying scandium according to the present invention subjects an acidic solution, which contains an element component including at least ion, while containing scandium, to solvent extraction by means of a mixed extractant containing a phosphoric acid-based extractant and a neutral extractant, thereby extracting scandium from the acidic solution. It is preferable that the phosphoric acid-based extractant is contained in the mixed extractant at a mixing molar ratio within the range of from 5% to 50% (inclusive). It is also preferable that the pH of the acidic solution is adjusted to a value within the range of from 0.0 to 2.0 (inclusive) before the solvent extraction.

1 . A method for purifying scandium, comprising:
 subjecting an acidic solution containing an element component including at least iron as well as scandium to solvent extraction using a mixed extractant containing 2-ethylhexylphosphonic acid 1-ethylhexyl or di(2,4,4-trimethylpentyl)phosphinic acid of a phosphoric acid-based extractant and tri-n-octylphosphine oxide of a neutral extractant to extract scandium from the acidic solution.   
     
     
         2 - 3 . (canceled) 
     
     
         4 . The method for purifying scandium according to  claim 1 , wherein the phosphoric acid-based extractant is contained in the mixed extractant at a mixing proportion in a range of between 5% or more and 50% or less in terms of molar ratio. 
     
     
         5 . The method for purifying scandium according to  claim 1 , wherein a pH of the acidic solution is adjusted to a range of between 0.0 or more and 2.0 or less and the acidic solution after pH adjustment is subjected to the solvent extraction. 
     
     
         6 . The method for purifying scandium according to  claim 1 , wherein the acidic solution is
 a solution obtained by adding an acid to nickel oxide ore and leaching scandium or a solution obtained by dissolving scandium oxide or scandium hydroxide in an acid, and   a pH of the acidic solution is adjusted to a range of between 0.0 or more and 2.0 or less and the acidic solution after pH adjustment is subjected to the solvent extraction.   
     
     
         7 . The method for purifying scandium according to  claim 1 , wherein the acidic solution further contains any one or more kinds of zirconium or thorium. 
     
     
         8 . A scandium extractant for extracting scandium from an acidic solution containing an element component including at least iron as well as scandium, comprising:
 2-ethylhexylphosphonic acid 1-ethylhexyl or di(2,4,4-trimethylpentyl)phosphinic acid of a phosphoric acid-based extractant and tri-n-octylphosphine oxide of a neutral extractant.   
     
     
         9 . The scandium extractant according to  claim 8 , wherein the phosphoric acid-based extractant is contained at a proportion in a range of between 5% or more and 50% or less in terms of molar ratio.