Separation of Rare Earth Elements from Base Metals in Concentrated HNO3, H2SO4 and HCl Solutions with Diglycolamide

The separation of Nd(III) and Dy(III) from Fe(III) and Ni(II) in relatively high concentrations of HNO 3 , HCl and H 2 SO 4 solutions (0.1 -7 M) was investigated using with 0.1 M N,N′-dimethyl-N,N′-di-n-octyl-diglycolamide (MODGA) in 80 vol% n-dodecane-20 vol% 2-ethylhexanol.In all systems, the extraction percentage (E%) value for Dy(III) is higher than that for Nd(III), and the E% values for Nd(III) and Dy(III) increase with an increase in the acid concentration.The extracted Nd(III) and Dy(III) in the organic phase can be back-extracted using distilled water.The back E% is dependent on the acid concentration in the forward extraction.Both Fe(III) and Ni(II) are poorly extracted in all systems, although Fe(III) is extracted at >2 M HCl.Therefore, Nd(III) and Dy(III) are readily separated from Fe(III) and Ni(II) in the HNO 3 and H 2 SO 4 systems.The separation of Nd(III) from Dy(III) is effectively performed in the forward extraction reaction at ~1 M HCl and ~1 M H 2 SO 4 and the back extraction of Nd(III) and Dy(III) from the organic phase produced by extraction from the ~1 M HNO 3 solution.