Mechanism of removing ferrum impurity in lanthanum refined by electron beam melting

• Published in: Journal of rare earths Vol. 39; no. 7; pp. 875 - 880
• Main Authors: Pang, Siming, Lu, Wenli, Yang, Zhenfei, Zhang, Xiaowei, Chen, Dehong, Wu, Daogao, Zhou, Lin, Miao, Ruiying
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.07.2021
• Subjects: Dynamics; Electron beam melting; Fe impurity; Lanthanum metal; Purification; Rare earths; Lanthanum metal; Fe impurity; Purification; Electron beam melting; Dynamics; Rare earths
• ISSN: 1002-0721; 2509-4963
• DOI: 10.1016/j.jre.2020.09.010

Removal feasibility of Fe impurity form La metal by electron beam melting (EBM) was analyzed, the removal mechanism was discussed, and the verification experiments were carried out in this study. The research results indicate that, the evaporation coefficient of Fe in La metal is 35–175 at 1800–3000 K, and Fe impurity can be removed by EBM; the removal efficiency of Fe impurity is improved with the increasing EBM power, the Fe concentration is significantly decreased from 1482 to 0.1 μg/g under 50 kW and 2400 s; the reaction of Fe removal by EBM follows the first-order rate law, and Fe impurity is removed by evaporation as a single atom; transport from the La melt to the liquid boundary layer of the Fe atom is rate-controlling step in the EBM when the EBM power is 30–50 kW. Electron beam melting (EBM), with the advantage of high temperature and high vacuum degree, can be demonstrated as an effective method to purify La in this study. Thereinto, the Fe concentration is significantly decreased from 1482 to 0.1 μg/g under 50 kW and 2400 s. The reaction of Fe removal by EBM follows the first-order rate law, and Fe impurity is removed by evaporation as a single atom. [Display omitted]