• Title/Summary/Keyword: molten salt

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Production Technology of Titanium by Kroll Process (Kroll법에 의한 타이타늄의 제조기술)

  • Sohn, Ho-Sang
    • Resources Recycling
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    • v.29 no.4
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    • pp.3-14
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    • 2020
  • Titanium sponge is industrially produced by the Kroll process. In order to understand the importance of the emerging smelting and recycling process, it is necessary to review the conventional production process of titanium. Therefore this paper provides a general overview of the conventional titanium manufacturing system mainly by the Kroll process. The Kroll process can be divided into four sub-processes as follows: (1) Chlorination of raw TiO2 with coke, by the fluidized bed chlorination or molten salt chlorination (2) Magnesium reduction of TiCl4 and vacuum distillation of MgCl2 and Mg by reverse U-type or I-type with reduction-distillation integrated retorts (3) Electrolysis process of MgCl2 by monopolar cells or multipolar cells to electrolyze into chlorine gas and Mg. (4) Crushing and melting process in which sponge titanium is crushed and then melted in a vacuum arc furnace or an electron beam furnace Although the apparatus and procedures have improved over the past 80 years, the Kroll process is the costly and time-consuming batch operation for the reduction of TiCl4 and the separation of MgCl2.

Effect of Calcination Temperature on Electromagnetic Wave Absorption Properties of M-type Ferrite Composite (하소온도가 M형 페라이트 복합재의 전자파 흡수 특성에 미치는 영향)

  • Seong Jun Cheon;Jae Ryung Choi;Sang Bok Lee;Je In Lee;Horim Lee
    • Composites Research
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    • v.36 no.5
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    • pp.289-296
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    • 2023
  • In this study, we investigated the electromagnetic properties and microwave absorption characteristics of M-type hexagonal ferrites, which are known as millimeter-wave absorbing materials, according to their calcination temperature. The M-type ferrites synthesized using a molten salt-based sol-gel method exhibited a single-phase M-type crystal structure at calcination temperatures above 850℃. The synthesized particle size increased as well with the calcination temperature. Saturation magnetization increased gradually with increasing calcination temperature, but coercivity reached a maximum at 1050℃ and then rapidly decreased. After preparing a thermoplastic polyurethane (TPU) composite containing 70 wt% of M-type ferrites, we measured the complex permittivity and permeability in the Q-band (33-50 GHz) and V-band (50-75 GHz) frequency ranges, where ferromagnetic resonance occurred. Strong magnetic loss from ferromagnetic resonance occurred in the 50 GHz band for all composite samples. Based on the measured results, we calculated the reflection loss of the TPU/M-type ferrite composite. By calculating the reflection loss of the M-type ferrite composite, the M-type ferrite calcined at 1250℃ showed excellent electromagnetic wave absorption performance of more than -20 dB at 52 GHz with a thickness of about 0.5 mm.

A Status of Technology and Policy of Nuclear Spent Fuel Treatment in Advanced Nuclear Program Countries and Relevant Research Works in Korea (선진 원자력발전국의 사용후핵연료 처리기술 및 정책현황과 우리나라의 관련연구 현황)

  • You, Gil-Sung;Choung, Won-Myung;Ku, Jeong-Hoe;Cho, Il-Je;Kook, Dong-Hak;Kwon, Kie-Chan;Lee, Won-Kyung;Lee, Eun-Pyo;Hong, Dong-Hee;Yoon, Ji-Sup;Park, Seong-Won
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.5 no.4
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    • pp.339-350
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    • 2007
  • Status on the spent nuclear fuel management policy and R&D plan of the major countries is surveyed. Also the prospect of the future R&D plan is suggested. Recently so-called fuel cycle nations, which have the reprocess policy of the spent fuel, announced new spent fuel management policy based on the advanced fuel cycle technology. The policy is focused to transmute highly radioactive material and material having a very long half-life, and to recycle the Pu and U contained in the spent fuel. In this way the radio-foxily of the spent fuel as well as the amount of the high level waste to be eventually disposed can greatly be reduced. Most of countries selected the wet process as a primary option for the treatment of the spent fuel since the advanced wet process, which is based on the existing PUREX process, looks more feasible as compared with the dry process. The wet process, however, is much more sensitive in terms of proliferation-resistance compared with the dry process. The pure Pu can easily be obtained by simply modifying the process. On the other hand the pure Pu can not be extracted in the dry process based on the high temperature molten salt process such as a pyroprocess. Even though the pyroprocess technology is very premature, it has a great merit. Thus it is necessary for Korea to have a long term strategy for pursuing a spent fuel treatment technology with a proliferation resistance and a great merit for the GEN-IV fuel cycles. Pyroprocess is one of the best candidates to satisfy these purposes.

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