Cite this article as: |
Eltefat Ahmadi, Ryosuke O. Suzuki, Tatsuya Kikuchi, Takumi Kaneko, and Yuta Yashima, 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(2020), No. 12, pp. 1635-1643. https://doi.org/10.1007/s12613-020-2162-5 |
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.
[1] |
G.Z. Chen, D.J. Fray, and T.W. Farthing, Direct electrochemical reduction of titanium dioxide to titanium in molten calcium chloride, Nature, 407(2000), No. 6802, p. 361. doi: 10.1038/35030069
|
[2] |
K. Ono and R.O. Suzuki, A new concept for producing Ti sponge: Calciothermic reduction, JOM, 54(2002), No. 2, p. 59. doi: 10.1007/BF02701078
|
[3] |
R.O. Suzuki, Calciothermic reduction of TiO2 and in situ electrolysis of CaO in the molten CaCl2, J. Phys. Chem. Solids, 66(2005), No. 2-4, p. 461. doi: 10.1016/j.jpcs.2004.06.041
|
[4] |
R.O. Suzuki, Direct reduction processes for titanium oxide in molten salt, JOM, 59(2007), No. 1, p. 68. doi: 10.1007/s11837-007-0014-7
|
[5] |
R.O. Suzuki and S. Inoue, Calciothermic reduction of titanium oxide in molten CaCl2, Metall. Mater. Trans. B, 34(2003), No. 3, p. 277. doi: 10.1007/s11663-003-0073-2
|
[6] |
H.W. Xie, H.J. Zhao, J.K. Qu, Q.S. Song, Z.Q. Ning, and H.Y. Yin, Thermodynamic considerations of screening halide molten-salt electrolytes for electrochemical reduction of solid oxides/sulfides, J Solid State Electrochem., 23(2019), No. 3, p. 903. doi: 10.1007/s10008-019-04193-w
|
[7] |
R.O. Suzuki and K. Ono, A new concept of sponge titanium production by calciothermic reduction of titanium oxide in the molten CaCl2, [in] C. Delong, R. W. Bradshaw, M. Matsunaga, G. R. Stafford, and P. C. Trulove, eds., Proceedings 13th International Symposium on Molten Salt, Philadelphia, 2002, p. 810.
|
[8] |
S. Natsui, T. Sudo, R. Shibuya, H. Nogami, T. Kikuchi, and R.O. Suzuki, Visualization of TiO2 reduction behavior in molten salt electrolysis, Metall. Mater. Trans. B, 51(2020), No. 1, p. 11. doi: 10.1007/s11663-019-01733-7
|
[9] |
N. Suzuki, M. Tanaka, H. Noguchi, S. Natsui, T. Kikuchi, and R.O. Suzuki, Reduction of TiS2 by OS process in CaCl2 melt, ECS Trans., 75(2016), No. 15, p. 507. doi: 10.1149/07515.0507ecst
|
[10] |
N. Suzuki, M. Tanaka, H. Noguchi, S. Natsui, T. Kikuchi, and R.O. Suzuki, Calcium reduction of TiS2 in CaCl2 melt, Mater. Trans., 58(2017), No. 3, p. 367. doi: 10.2320/matertrans.MK201613
|
[11] |
E. Ahmadi, A. Fauzi, H. Hussin, N. Baharun, K.S. Ariffin, and S.A. Rezan, Synthesis of titanium oxycarbonitride by carbothermal reduction and nitridation of ilmenite with recycling of polyethylene terephthalate (PET), Int. J. Miner. Metall. Mater., 24(2017), No. 4, p. 444. doi: 10.1007/s12613-017-1425-2
|
[12] |
E. Ahmadi, Y. Yashima, R.O. Suzuki, and S.A. Rezan, Formation of titanium sulfide from titanium oxycarbonitride by CS2 gas, Metall. Mater. Trans. B, 49(2018), No. 4, p. 1808. doi: 10.1007/s11663-018-1278-8
|
[13] |
E. Ahmadi and R.O. Suzuki, An innovative process for production of Ti metal powder via TiSx from TiN, Metall. Mater. Trans. B, 51(2020), No. 1, p. 140. doi: 10.1007/s11663-019-01730-w
|
[14] |
E. Ahmadi, S.A. Rezan, N. Baharun, S. Ramakrishnan, A. Fauzi, and G.Q. Zhang, Chlorination kinetics of titanium nitride for production of titanium tetrachloride from nitrided ilmenite, Metall. Mater. Trans. B, 48(2017), No. 5, p. 2354. doi: 10.1007/s11663-017-1011-z
|
[15] |
E. Ahmadi, N.I. Shoparwe, N. Ibrahim, S.A.R. Sheikh Abdul Hamid, N. Baharun, K.S. Ariffin, H. Hussin, and M.N. Ahmad Fauzi, The effects of experimental variables on iron removal from nitrided malaysian ilmenite by becher process, [in] B.R. Davis, M.S. Moats, S.J. Wang,et al., eds., Extraction 2018, The Minerals, Metals & Materials Series, Springer, Cham, 2018, p. 1383.
|
[16] |
R.O. Suzuki, K. Ono, and K. Teranuma, Calciothermic reduction of titanium oxide and in-situ electrolysis in molten CaCl2, Metall. Mater. Trans. B, 34(2003), No. 3, p. 287. doi: 10.1007/s11663-003-0074-1
|
[17] |
C.S. Wu, M.S. Tan, G.Z. Ye, D.J. Fray, and X.B. Jin, High-efficiency preparation of titanium through electrolysis of carbo-sulfurized titanium dioxide, ACS Sustainable Chem. Eng., 7(2019), No. 9, p. 8340. doi: 10.1021/acssuschemeng.8b06801
|
[18] |
S.K. Sadrnezhaad, E. Ahmadi, and M. Malekzadeh, Mechanism of reaction of molten NiTi with EBM graphite crucible, Mater. Sci. Technol., 25(2009), No. 6, p. 699. doi: 10.1179/174328408X317075
|
[19] |
R.O. Suzuki, H. Noguchi, and M. Tanaka, Method for Producing Metallic Titanium, Japanese Patent, Appl. 6495142B2, 2019.
|
[20] |
R.O. Suzuki, N. Suzuki, Y. Yashima, S. Natsui, and T. Kikuchi, Calciothermic reduction and electrolysis of sulfides in CaCl2 melt, [in] B.R. Davis, M.S. Moats, S.J. Wang, et al., eds., Extraction 2018, The Minerals, Metals & Materials Series, Springer, Cham, 2018, p. 763.
|
[21] |
S.K. Basu and M. Taniguchi, Thermal analysis and kinetics of oxidation of “TiS2” and “Ti2S3”, Thermochim. Acta, 109(1986), No. 1, p. 253. doi: 10.1016/0040-6031(86)85026-2
|
[22] |
T. Kimura, Molten salt synthesis of ceramic powders [in] C. Sikalidis, ed., Advances in Ceramics - Synthesis and Characterization, Processing and Specific Applications, Intech, 2011, p. 75.
|
[23] |
Z.Z. Fang, J.D. Paramore, P. Sun, K.S. Ravi Chandran, Y. Zhang, Y. Xia, F. Cao, M. Koopman, and M. Free, Powder metallurgy of titanium – past, present, and future, Int. Mater. Rev., 63(2018), No. 7, p. 407. doi: 10.1080/09506608.2017.1366003
|
[24] |
O. Kanou, N. Fukada, and S. Takenaka, The use of HDH titanium alloy powder for additive manufacturing application, J. Jpn. Soc. Powder Powder Metall., 64(2017), No. 6, p. 295. doi: 10.2497/jjspm.64.295
|