Purification of rare earth bis(trifluoromethyl-sulfonyl)amide salts by hydrometallurgy and electrodeposition of neodymium metal using potassium bis(trifluoromethyl-sulfonyl)amide melts
Purification of rare earth bis(trifluoromethyl-sulfonyl)amide salts by hydrometallurgy and electrodeposition of neodymium metal using potassium bis(trifluoromethyl-sulfonyl)amide melts
复制标题
利用双(三氟甲基磺酰)酰胺钾熔体湿法冶金和电沉积金属钕来纯化稀土双(三氟甲基磺酰)酰胺盐
DOI：
10.1016/j.seppur.2016.06.044
复制
发表时间：
2016
影响因子：
8.6
通讯作者：
Satoshi Kawakami
中科院分区：
文献类型：
--
作者：
Hisashi Ota;Masahiko Matsumiya;Takahiro Yamada;Tetsuo Fujita;Satoshi Kawakami
本文报道了一种新的实验室规模的湿法冶金工艺和使用双（三氟甲基磺酰）氨基钾（KTFSA）熔体电沉积从Nd-Fe-B磁体废料中回收稀土（RE）元素。在实验室规模下进行调查，以评估基于RE酰胺盐的浸出、脱铁和纯化的工艺的潜力。在使用3.4 kg氧化Nd-Fe-B和14.2 L 1，1，1-三氟-N-[（三氟甲基）磺酰基]甲磺酰胺（HTFSA）的水溶液的浸出过程中，在13 h内浸出83.0%的Nd和0.98%的Fe，表明在实验室规模下进行了稀土元素的选择性浸出。然后用KOH或氧化Nd-Fe-B作沉淀剂进行除铁，成功地将100.0%的Fe与稀土组分分离。此外，从喷雾干燥器中回收了4.07 kg纯化的酰胺盐（M（TFSA）3，M = Pr，Nd，Dy，B，Al和微量元素），研究了Nd（III）在含M（TFSA）3（RE组分的摩尔分数：xRE= 0.1）的KTFSA熔体中的电化学行为。电化学分析表明，Nd（III）在+1.0 V vs. K/K+附近的还原峰是由于以下反应：Nd（III）+ 3e−→ Nd（0）。通过半微分分析估算出Nd（III）在483 K时的扩散系数为3.14 × 10− 10 m2 s − 1，与Nd（III）在含纯Nd（TFSA）3盐（xNd= 0.1）的KTFSA熔体中的扩散系数相近。在483 K下，在+0.8Vvs. K/K+恒电位条件下，进行了Nd的电沉积。电沉积物具有细小的金属颗粒的表面形态。通过扫描电子显微镜/能量色散X射线能谱、X射线光电子能谱和X射线衍射分析，证实电沉积物是中间层中的Nd金属。最后，我们证明了新的回收过程的有效性，为实际使用，通过估计整个材料流。
This paper reports a novel bench-scale hydrometallurgical procedure and electrodeposition using potassium bis(trifluoromethyl-sulfonyl)amide (KTFSA) melts for the recovery of rare earth (RE) elements from Nd-Fe-B magnet waste. The investigations were performed at bench scale to assess the potential of a process based on leaching, deironization, and purification of RE amide salts. In the leaching process using 3.4 kg of oxidized Nd-Fe-B and 14.2 L of an aqueous solution of 1,1,1-trifluoro-N-[(trifluoromethyl)sulfonyl]methanesulfonamide (HTFSA), 83.0% Nd and 0.98% Fe were leached in 13 h, indicating that selective leaching of RE elements was performed at bench scale. Then, KOH or oxidized Nd-Fe-B was used as a precipitation agent in the deironization process and 100.0% Fe was successfully separated from RE components. Moreover, 4.07 kg of purified amide salts (M(TFSA)3, M = Pr, Nd, Dy, B, Al, and trace elements) were recovered from a spray dryer.The electrochemical behavior of Nd(III) in KTFSA melts containing M(TFSA)3(molar fraction of RE components:xRE= 0.1) was investigated in this study. Electrochemical analysis revealed that the reduction peak of Nd(III) at around +1.0 V vs. K/K+was due to the following reaction: Nd(III) + 3e−→ Nd(0). The diffusion coefficient of Nd(III) was estimated to be 3.14 × 10−10m2s−1at 483 K by semi-differential analysis, which is similar to that of Nd(III) in KTFSA melts containing pure Nd(TFSA)3salts (xNd= 0.1). The electrodeposition of Nd was performed under potentiostatic conditions of +0.8 V vs. K/K+at 483 K. The electrodeposits had a fine surface morphology with small metal particles. The electrodeposits were confirmed to be Nd metal in the middle layer analyzed by scanning electron microscopy/energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. Finally, we demonstrated the effectiveness of the novel recovery process for practical use by estimating whole material flow.