Extraction of ytterbium via co-reduction of Al(III) and Yb(III) from LiCl–KCl melt on W electrode

Abstract

Anhydrous ytterbium chloride was obtained via solid-phase reaction from Yb2O3 with AlCl3 as a chlorination agent. The electrochemical behavior of the chloridized Yb2O3 was investigated on W electrodes in LiCl–KCl and LiCl–KCl–AlCl3 melts by cyclic voltammetry and square wave voltammetry. The results showed that the reduction/reoxidation of Yb(III)/Yb(II) was reversible and controlled by diffusion. The signals related to the formation of two Al–Yb intermetallic compounds were detected in LiCl–KCl–AlCl3 melt. Potentiostatic electrolysis was carried out in LiCl–KCl–AlCl3–YbCl3 melt on W electrodes at 943 K at different potentials and Al3Yb, Al2Yb, AlLi and Al2Li3 phases were detected in deposits. Then, the extraction of ytterbium was performed. The currents evolution was recorded by square wave voltammetry and the extraction efficiency was evaluated via inductive coupled plasma atomic emission spectrometer analysis during electrolysis. The initial extraction rate is much higher than that at longer times. The extraction efficiency was about 98.0 % for Yb(III) after potentiostatic electrolysis for 60 h at −1.84 V in LiCl–KCl–AlCl3–YbCl3 melt.