Resources Recycling (자원리싸이클링)

The Korean Institute of Resources Recycling (한국자원리싸이클링학회)
권호 표지
DOI QR코드

DOI QR Code

A Study on the Formation Mechanism of Titanium Sponge in the Kroll Process

Kroll법에 의한 타이타늄 스폰지 생성기구에 관한 연구

  • Jung, Jae-Young (Automobile Parts & Materials Research Center, Kyungpook National University) ;
  • Sohn, Ho-Sang (Automobile Parts & Materials Research Center, Kyungpook National University)
  • 정재영 (경북대학교 자동차부품소재연구소) ;
  • 손호상 (경북대학교 자동차부품소재연구소)
  • Received : 2017.08.10
  • Accepted : 2017.09.28
  • Published : 2017.10.31
Download PDF
⟨ Previous Next ⟩

Abstract

In this study, we investigated the effect of $TiCl_4$ injection time on the Kroll reaction at a given weight ratio of $TiCl_4$ and Mg. The reduction reaction was investigated by measuring the temperature change according to $TiCl_4$ injection time and observing the cross section and appearance of the Ti sponge after the reaction. The temperature increment due to Kroll reaction heat generation was found to be linearly proportional to the $TiCl_4$ feed rate. In the graph of $TiCl_4$ injection time and reduction tank temperature, initial temperature peaks were observed irrespective of the injection conditions. This is interpreted to mean a temporary interruption of reaction due to $MgCl_2$ formation after the initial Kroll reaction. In addition, when the cross section of the sponge was observed, a large amount of spherical Mg particles was observed in $MgCl_2$. We can infer that this is the process of continuously feeding the unreacted Mg surface, so that a continuous Kroll reaction takes place. The sponge appearance showed that the coalescence or growth of the Kroll reacted Ti particles can be controlled by the cooling rate.

본 연구에서는 $TiCl_4$ 투입시간의 효과가 $TiCl_4$ and Mg의 주어진 중량비율에서 Kroll반응에 미치는 효과를 조사하였다. 그리고 환원반응은 $TiCl_4$ 투입시간에 따라 온도변화를 측정하고, 반응 후 Ti 스폰지 단면과 외관을 관찰함으로써 조사되었다. Kroll 반응열 생성에 의한 온도 증분은 $TiCl_4$ 투입속도에 직선적으로 비례하는 것으로 파악되었다. $TiCl_4$ 투입시간과 환원조 온도 그래프를 보면, 초기 온도 피크가 주입조건에 무관하게 모두 관찰되었다. 이는 초기 Kroll 반응후 $MgCl_2$ 형성으로 인한 일시적인 반응 중단을 의미하는 것으로 해석된다. 또한 스폰지 단면을 관찰해보면, 구형 Mg 입자상이 $MgCl_2$ 내부에 다량으로 관찰되었다. 우리는 이것이 지속적인 Kroll 반응이 일어나도록 미반응 Mg 표면을 계속적으로 공급하는 과정이라 추론할 수 있다. 주사전자현미경으로 스폰지 외형을 관찰한 결과는 Kroll 반응된 Ti 입자들의 합체나 성장이 냉각속도에 의해 제어될 수 있음을 보여주었다.

Keywords

References

  1. W. Kroll, 1940 : The Production of Ductile Titanium, Trans. Electrochem. Soc., 78, pp.35-47. https://doi.org/10.1149/1.3071290
  2. T. Fukuyama, M. Koizumi, M. Hanaki, and S. Kosemur, 1993 : Production of Titanium Sponge and Ingot at Toho Titanium Co., Ltd., Shigen-to-Sozai, 109, pp.1157-1163. https://doi.org/10.2473/shigentosozai.109.1157
  3. A. Moriya and A. Kanai, 1993 : Titanium Sponge Production at Sumitomo Sitix Corporation, Shigen-to-Sozai, 109, pp.1164-1169. https://doi.org/10.2473/shigentosozai.109.1164
  4. Ho-Sang Sohn and Jae-Young Jung, 2016 : Current Status of Ilmenite Beneficiation Technology for Production of $TiO_2$, J. of Korean Inst. of Resources Recycling, 20(5), pp.64-74. https://doi.org/10.7844/KIRR.2011.20.5.064
  5. Ho-Sang Sohn and Jae-Young Jung, 2016 : Current Status of Titanium Smelting Technology, J. of Korean Inst. of Resources Recycling, 20(4), pp.68-79.
  6. G. Z. Chen, D. J. Fray, and T. W. Farthing, 2000 : Direct electrochemical reduction of titanium dioxide to titanium in molten calcium chloride, Nature, 407, pp.361-364. https://doi.org/10.1038/35030069
  7. EHK TECHNOLOGIES, Dec. 2003 : Summary of Emerging Titanium Cost Reduction Technologies, A Study Performed For US Department of Energy and Oak Ridge National Laboratory, Subcontract 4000023694, pp.1-55.
  8. C. H. R. V. S. Nagesh, C. H. S. Rao, N. B. Ballal, and P. K. Rao, 2004 : Mechanism of Titanium Sponge Formation in the Kroll Reduction Reactor, Metall. Mater. Trans. B 35, pp.65. https://doi.org/10.1007/s11663-004-0097-2
  9. Jae Chan Lee, Ho Sang Sohn, and Jae Young Jung, 2012 : Effect of $TiCl_4$ Feeding Rate on the Formation of Titanium Sponge in the Kroll Process, Korean J. Met. Mater. 50(10), pp.745-751. https://doi.org/10.3365/KJMM.2012.50.10.745
  10. F. G. Reshetnikov and E. N. Oblomeev, 1957 : Mechanism of formation of zirconium sponge in zirconium production by the magnesothermic process, Atomic Energy, 2(5), pp.561-564. https://doi.org/10.1007/BF01491004