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Tantalum Metal Production Through High-Efficiency Electrochemical Reduction of TaS2 in Molten CaCl2

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Abstract

The electro-calciothermic reduction of tantalum sulfide (TaS2) was applied to open a new pathway for producing high-purity Ta powders applicable for tantalum electrolytic capacitors. The supplied electric charge was varied to electrochemically reduce the sulfide at 900 °C using Ca in molten CaCl2−xCaS (x = 0.1, 0.5 mol%) salts. The cleaner TaS2 could also be prepared via the highly efficient carbo-sulfidation of Ta2O5 using S2 gas. The plate-like Ta particles with internal voids and coral structures were obtained through the electrochemical reduction of the sulfides. Sulfur removal was achieved rapidly from TaS2. Ta powder with 0.08 mass% O and 0.01 mass% S was successfully produced from Ta2O5 via clean TaS2. It was obtained by increasing the electric charge to two times higher than that required to generate the stoichiometric amount of Ca in the CaCl2 melt. Therefore, the electrometallurgical reduction of TaS2 could be a promising, cost-effective, and sustainable approach for producing high-purity Ta powders.

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Acknowledgements

This work was financially supported by the Japan Society for the Promotion of Science (JSPS) Postdoctoral Fellowship (No. P18054), Grants-in-Aid for Scientific Research (KAKENHI Grant Nos 18F18054 and 17H03434) and the Japan Mining Industry Association. The kind support from JSPS and the International Affairs Office of the Faculty of Engineering, Hokkaido University, are also gratefully acknowledged.

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Authors and Affiliations

  1. Division of Materials Science and Engineering, Faculty of Engineering, Hokkaido University, N13W8, Kita-ku, Sapporo, 060-8628, Japan

    Eltefat Ahmadi & Ryosuke O. Suzuki

  2. Japan Society for the Promotion of Science (JSPS), Chiyoda-ku, Tokyo, 102-0083, Japan

    Eltefat Ahmadi

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  1. Eltefat Ahmadi
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  2. Ryosuke O. Suzuki
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Correspondence to Eltefat Ahmadi or Ryosuke O. Suzuki.

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Ahmadi, E., Suzuki, R.O. Tantalum Metal Production Through High-Efficiency Electrochemical Reduction of TaS2 in Molten CaCl2. J. Sustain. Metall. 7, 437–447 (2021). https://doi.org/10.1007/s40831-021-00347-1

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