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Electrical conductivity optimization of the Na3AlF6–Al2O3–Sm2O3 molten salts system for Al–Sm intermediate binary alloy production

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Abstract

Metal Sm has been widely used in making Al–Sm magnet alloy materials. Conventional distillation technology to produce Sm has the disadvantages of low productivity, high costs, and pollution generation. The objective of this study was to develop a molten salt electrolyte system to produce Al–Sm alloy directly, with focus on the electrical conductivity and optimal operating conditions to minimize the energy consumption. The continuously varying cell constant (CVCC) technique was used to measure the conductivity for the Na3AlF6–AlF3–LiF–MgF2–Al2O3–Sm2O3 electrolysis medium in the temperature range from 905 to 1055°C. The temperature (t) and the addition of Al2O3 (W(Al2O3)), Sm2O3 (W(Sm2O3)), and a combination of Al2O3 and Sm2O3 into the basic fluoride system were examined with respect to their effects on the conductivity (κ) and activation energy. The experimental results showed that the molten electrolyte conductivity increases with increasing temperature (t) and decreases with the addition of Al2O3 or Sm2O3 or both. We concluded that the optimal operation conditions for Al–Sm intermediate alloy production in the Na3AlF6–AlF3–LiF–MgF2–Al2O3–Sm2O3 system are W(Al2O3) + W(Sm2O3) = 3wt%, W(Al2O3):W(Sm2O3) = 7:3, and a temperature of 965 to 995°C, which results in satisfactory conductivity, low fluoride evaporation losses, and low energy consumption.

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Acknowledgements

This work was financially supported by the National Natural Science Foundation of China (Nos. 51564015 and 51674126), the Graduate Student Innovation Special Fund of Jiangxi Province (YC2015-B064), the Science and Technology Research Project of Jiangxi Department of Education (GJJ150664), the Outstanding Doctoral Dissertation Project Fund of JXUST (YB2016007), and the Scientific Research Fund of JXUST (NSFJ2014-G09).

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Authors and Affiliations

  1. Institute of Metallurgical and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou, 341000, China

    Chun-fa Liao, Yun-fen Jiao, Xu Wang, Bo-qing Cai, Qiang-chao Sun & Hao Tang

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  1. Chun-fa Liao
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  2. Yun-fen Jiao
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  3. Xu Wang
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Correspondence to Yun-fen Jiao.

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Liao, Cf., Jiao, Yf., Wang, X. et al. Electrical conductivity optimization of the Na3AlF6–Al2O3–Sm2O3 molten salts system for Al–Sm intermediate binary alloy production. Int J Miner Metall Mater 24, 1034–1042 (2017). https://doi.org/10.1007/s12613-017-1493-3

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  • DOI: https://doi.org/10.1007/s12613-017-1493-3

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