Extraction of neodymium from other fission products by co‐reduction of Sn and Nd

Abstract

High temperature processing is an important method for recovering long‐lived elements from spent nuclear fuel. Electrolysis is the key technology for high temperature processing. The electrochemical behaviors of Sn2+, Nd3+ and the mechanisms of Sn‐Nd alloy formation were investigated on a Mo electrode at 873 K by conducting a series of electrochemical techniques. The results showed the deposition of Nd on inert electrode is a two‐step process in LiCl‐KCl‐SnCl2 (2.0 wt.%) melt system. Subsequently, the electrochemical extraction of Nd from molten chlorides were carried out on the Mo electrode at temperature of 873 K by the potentiostatic electrolysis at −1.2 V for 40 hr. Besides, the extraction efficiency is 97.6%. A series of potentiostatic electrolysis were carried out at potential range between −1.0 and − 1.4 V. The NdSn3 alloy was obtained by electrolysis at −1.2 V. This deposition potential is consistent with the predicted results of the mathematical model. The micro‐chemical analysis and morphology analysis of the deposits was characterized by energy dispersive spectrometry (EDS) with scanning electron microscopy (SEM) equipped. The composition of the deposits was analyzed by X‐ray diffraction (XRD) and inductive coupled plasma atomic emission spectrometer (ICP‐AES).

Investigation on the Electrochemical Behaviour and Deposition Mechanism of Neodymium in NdF3–LiF–Nd2O3 Melt on Mo Electrode

“…Commonly investigated salt combinations include chlorides, fluorides, and oxides of alkali and alkaline earth metals and neodymium [8,10,11]. The electrolytes made of molten chlorides are mainly composed of NdCl 3 + LiCl + KCl [1][2][3]7,[11][12][13][14][15][16]. Fluoride electrolytes are considered more suitable because of their higher conductivity, lower hygroscopy, and higher current efficiency of the neodymium deposition compared to the chloride melts [17,18].…”

Electrode reaction of Pr on Sn electrode and its electrochemical recovery fromLiCl‐KClmolten salt

“…If pure Pr is taken as standard states, the equilibrium potential values relative to Ag/AgCl can be expressed as ΔE i vs Pr 3+ /Pr(0) (ie, depolarization value) shown in Figure 5B, and these values are summarized in Table 1. Based on formula (12), the partial molar Gibbs free energy Δ G Pr and activity a Pr of metallic praseodymium in the Pr-Sn alloys were figured up.…”

“…6 The recovery of actinide elements by partitioning and transmutation, considered as one of the promising options for spent fuel management, can make full use of nuclear fuel and minimize nuclear wastes, 7 which is conducive to increase the utilization rate of nuclear energy. [8][9][10][11][12][13] Since molten salt has some excellent characteristics, 14,15 for instance, radiation resistance, short cooling time, and antiproliferative properties, pyrometallurgical technology, employing molten salt as medium, is considered as a promising method in the field of separation and extraction of actinides, 16,17 which mainly includes reduction extraction in molten saltliquid metal system, 18,19 electrorefining, 20,21 and electrochemical extraction using reactive cathodes. [22][23][24][25][26] Wherein, electrochemical extraction is the most extensive pyrochemical separation process.…”