Jing Pan,Wenhao Li,Yongde Yan,Xuepeng Wang,Sihao Wang,Yun Xue,Fuqiu Ma,Kai Zhu,Wei Liu
Effective extraction of lanthanum (La) from spent nuclear fuel is crucial for promoting the sustainable use of nuclear energy. Liquid aluminum (Al) electrode shows significant advantages as active cathodes in the electrochemical extraction of lanthanides (Ln). However, the electrolytic reduction of La by liquid Al in NaCl-KCl melt has not received adequate attention and understanding. For this reason, the electrochemical recovery of La from NaCl-KCl melt using a liquid Al cathode has been investigated in this paper by a series of electrochemical methods. The results indicate that the reduction of La(III) on the W electrode occurs as a one-step process and the reaction is irreversible. The diffusion coefficient of La(III)/La was determined to be 6.70×10 -5 cm 2 s -1 . Meanwhile, the co-reduction process of La(III) and Al(III) on the W electrode was systematically investigated to explore the potential for forming binary intermetallic compounds. In addition, the exchange current density (0.025-0.030 A cm -2 ) at different temperatures was determined using linear polarization (LP), further elucidating the temperature dependence of the exchange current density. Finally, La was successfully extracted as an alloy by potentiostatic electrolysis on the Al electrode. This study provides promising insights for the extraction of La in NaCl-KCl melt on liquid Al electrode.
Minpeng Lei,Yun Lei,Shiding Wang,Dongfang Yang,Shaoyuan Li,Wenhui Ma
Spent nickel-metal hydride (NiMH) batteries are a significant secondary resource for recovering rare earth elements (REEs), particularly lanthanum (La). However, extracting La from the La 2 O 3 -containing oxide slag generated during pyrometallurgical recycling remains a major challenge. This study proposes a novel approach to address this issue by synergistically extracting La from La 2 O 3 -containing oxide slag while simultaneously upgrading metallurgical-grade silicon (MG-Si, 99.2%) to high-purity Si (99.991%). The process begins with the extraction of La from the La 2 O 3 -containing oxide slag using MG-Si as a reductant, yielding a useful Si-La alloy. This is followed by a three-stage leaching process to further separate the Si-La alloy and purify the Si powder. In the primary leaching stage, the Si-La alloy powder is separated into a La-containing acidic solution and residual Si powder using HCl solution. In the secondary leaching stage, Fe impurities in the residual Si powder are removed using a mixed acids solution of HF and HCl. In the tertiary leaching stage, the Si powder is further purified to 99.991% using HCl. Finally, the La ions in the La-containing acidic solution are selectively precipitated using hydrofluoric acid (HF) and ammonia (NH 3 ·H 2 O), respectively, resulting in high-purity LaF 3 (96.2%) and LaOCl (99.4%). This new method simultaneously recovers La from La 2 O 3 -containing oxide slag and enhances Si purity from 99.2 to 99.991%.
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