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Towards a sustainable technology for production of extra-pure Ti metal: Electrolysis of sulfurized Ti(C,N) in molten CaCl2

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Abstract

A new concept for producing highly pure Ti metal powder from ilmenite (FeTiO3) is proposed in this article. Titanium nitride (TiN) or titanium oxycarbonitride (TiOxCyNz) could be synthesized in the first step via the simultaneous carbothermal reduction and nitridation (CTRN) of FeTiO3 to remove oxygen roughly. To separate oxygen completely, high-quality TiS2 samples were then synthesized from TiN and TiC using S2 gas, and the clean sulfides were finally reduced to α-Ti powders with spherical morphology using electrolysis in molten CaCl2. X-ray diffraction (XRD), scanning electron microscopy (SEM) in conjunction with energy-dispersive X-ray spectroscopy (EDS), and elemental LECO analysis were used to study the phases and microstructures of the sulfides and the electrochemically reduced powders. The Ti powder showed no carbon contamination and consisted of high-purity foil-like Ti sheets with very low oxygen, carbon, and nitrogen contents of less than 0.15wt% O, 0.02wt% C, and 0.003wt% N, respectively. The quality of the Ti powder was much higher than that of the powder obtained using the conventional OS process (proposed by K. Ono and R.O. Suzuki) starting directly from the oxides.

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Acknowledgements

This work is the financially supported by The Japan Society for the Promotion of Science (JSPS) Postdoctoral Fellowship (No. P18054), Grants-in-Aid for Scientific Research (KAKENHI) (Nos. 18F18054 and 17H03434), the Ministry of Education, Culture, Sports, Science and Technology (MEXT) Nanotechnology Platform Program (No. A-19-HK-0034), 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, Sapporo, 060-8628, Japan

    Eltefat Ahmadi, Ryosuke O. Suzuki, Tatsuya Kikuchi, Takumi Kaneko & Yuta Yashima

  2. Japan Society for the Promotion of Science (JSPS), 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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  3. Tatsuya Kikuchi
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  4. Takumi Kaneko
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  5. Yuta Yashima
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Correspondence to Eltefat Ahmadi.

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Ahmadi, E., Suzuki, R.O., Kikuchi, T. et al. Towards a sustainable technology for production of extra-pure Ti metal: Electrolysis of sulfurized Ti(C,N) in molten CaCl2. Int J Miner Metall Mater 27, 1635–1643 (2020). https://doi.org/10.1007/s12613-020-2162-5

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  • DOI: https://doi.org/10.1007/s12613-020-2162-5

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