• Title/Summary/Keyword: carbothermic

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Production of Fe-Si-Cr Ferro Alloy by Using Mixed Silicothermic and Carbothermic Reduction (실리콘 및 탄소 복합 열환원 반응을 이용한 페로실리크롬 합금철의 제조)

  • Kim, Jong Ho;Jung, Eun Jin;Lee, Go-Gi;Jung, Woo-Gwang;Yu, Seon Jun;Chang, Young Chul
    • Korean Journal of Materials Research
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    • v.27 no.5
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    • pp.263-269
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    • 2017
  • Fe-Si-Cr ferroalloy is predominantly produced by carbothermic reduction. In this study, silicothermic and carbothermic mixed reduction of chromite ore to produce Fe-Si-Cr alloy is suggested. As reductants, silicon and silicon carbide are evaluated by thermochemical calculations, which prove that silicon carbide can be applied as a raw material. Considering the critical temperature of the change from the carbide to the metallic form of chromium, thereduction experiments were carried out. In these high temperature reactions, silicon and silicon carbide act as effective reductants to produce Fe-Si-Cr ferroalloy. However, at temperatures lower than the critical temperature, silicon carbide shows a slow reaction rate for reducing chromite ore. For the proper implementation of a commercial process that uses silicon carbide reductants, the operation temperature should be kept above the critical temperature. Using equilibrium calculations for chromite ore reduction with silicon and silicon carbide, the compositions of reacted metal and slag were successfully predicted. Therefore, the mass balance of the silicothermic and carbothermic mixed reduction of chromite ore can be proposed based on the calculations and the experimental results.

Synthesis of Titanium Diboride and Composites by Carbothermic Reduction of Titanium Oxide and Boric Oxide

  • Yoon, Su-Jong;Jha, Animesh
    • The Korean Journal of Ceramics
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    • v.4 no.4
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    • pp.387-393
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    • 1998
  • The formation of titanium diboride ($TiB_2$ ) via the reduction of $TiO_2$ with boric oxide and carbon was studied in a partially reducing atmosphere of argon mixed with 4 vol.%H2. The effect of reaction time, temperature, partial pressure of nitrogen and $TiO_2/B_2_O3$ stoichiometric ratio on the reducibility of oxides has been studied. The phases formed were analysed by using X-ray rowder diffraction and scanning sosctron microscopic techniques. In this paper, we also investigated the presence of $CaC_2$ as a reducing agent on the reducibility of oxide mixtures and on the Ti-B-C-Ca-O phase equilibria. The morphology of $TiB_2$ formed in the presence of $CaC_2$ is compared with the microstructure of $TiB_2$ formed as a consequence of carbothermic reduction. The observed variation in $TiB_2$ crystals formed is also explained.

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Fabrication of Nitride Fuel Pellets by Using Simulated Spent Nuclear Fuel (모의 사용후 핵연료를 이용한 질화물 핵연료 소결체 제조)

  • Ryu, Ho-Jin;Lee, Jae-Won;Lee, Young-Woo;Lee, Jung-Won;Park, Geun-Il
    • Journal of Powder Materials
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    • v.15 no.2
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    • pp.87-94
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    • 2008
  • In order to investigate a nitriding process of spent oxide fuel and the subsequent change in thermal properties after nitriding, simulated spent fuel powder was converted into a nitride pellet with simulated fission product elements through a carbothermic reduction process. Nitriding rate of simulated spent fuel was decreased with increasing of the amount of fission products. Contents of Ba and Sr in simulated spent fuel were decreased after the carbothermic reduction process. The thermal conductivity of the nitride pellet was decreased by an addition of fission product element but was higher than that of the oxide fuel containing fission product elements.

Production of SrCO3 from SrSO4 through the Black Ash Process (Black Ash법을 이용한 SrSO4로부터 SrCO3 제조)

  • Kang, Jungshin;Lee, Jin-Young
    • Resources Recycling
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    • v.30 no.5
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    • pp.49-56
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    • 2021
  • In this study, using strontium sulfate (SrSO4) recovered from magnetite ore in Hongcheon, the Black Ash process was used to produce strontium carbonate (SrCO3). In the carbothermic reaction step, SrSO4 was reacted with carbon (C) at 1273 K under Ar gas atmosphere using a gas-tight quartz reactor to produce strontium sulfide (SrS). Afterward, water leaching of the residues produced from the carbothermic reaction at 353 K and carbonation of the leaching solution using sodium carbonate (Na2CO3) at 298 K were conducted to produce SrCO3. The results of this study demonstrate the feasibility of the production of SrCO3 via the Black Ash process using domestic magnetite ore containing strontium (Sr).

Effect of physicochemical properties and feed mix ratios on the carbothermic reductions of iron ore with coke

  • S.R.R. Munusamy;S. Manogaran;F. Abdullah;N.A.M. Ya'akob;K. Narayanan
    • Advances in materials Research
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    • v.13 no.3
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    • pp.161-171
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    • 2024
  • This study aimed to investigate the effect of physicochemical properties and mix ratios of iron ore (oxide feed): coke (reductant) on the carbothermic reductions of iron ore. Coke size was fixed at ≤63 ㎛ while iron ore size varied between 150-63 ㎛ and ≤63 ㎛ respectively. Mix ratios were changed from 100:0 (reference) to 80:20 and 60:40 while the temperature, heating rate and soaking duration in muffle furnace were fixed at 1100 ℃, 10 ℃/min and 1 hour. Particle size analyzer, XRF, CHNS and XRD analyses were used for determination of raw feed characteristics. The occurrence of phase transformations from various forms of iron oxides to iron during the carbothermal reductions were identified through XRD profiles and supported with weight loss (%). XRF analysis proved that iron ore is of high grade with 93.4% of Fe2O3 content. Other oxides present in minor amounts are 2% Al2O3 and 1.8% SiO2 with negligible amounts of other compounds such as MnO, K2O and CuO. Composite pellet with finer size iron particles (≤63 ㎛) and higher carbon content of 60:40 exhibited 45.13% weight lost compared to 32.30% and 3.88% respectively for 80:20 and 100:0 ratios. It is evident that reduction reactions can only occur with the presence of coke, the carbon supply. The small weight loss of 3.88% at 100:0 ratio occurs due to the removal of moisture and volatiles and oxidations of iron ore. Higher carbon supply at 60:40 leads into better heat and mass transfer and diffusivity during carbothermic reductions. Overall, finer particle size and higher carbon supply improves reactivity and gas-solid interactions resulting in increased reductions and phase transformations.

Thermodynamic Study for P Reduction from Slag to Molten Steel by using the Microwave Heating (마이크로웨이브 가열을 이용한 슬래그로부터 인의 용철로의 환원이동에 관한 열역학적 고찰)

  • Lee, Joon-Ho;Kim, Eun-Ju;Kim, Tae-Young;Kang, Youn-Bae
    • Korean Journal of Materials Research
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    • v.20 no.1
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    • pp.42-46
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    • 2010
  • Phosphorus exhibits considerable segregation in steelmaking slag. In order to recover phosphorus from slag to $K_3PO_4$ via molten iron, a carbothermic reaction using microwave heating was suggested recently. The carbothermic reduction of phosphorus from slag to molten iron using microwave heating was carried out at 2073K. However, at this temperature the thermodynamic properties of both slag and molten iron cannot be determined experimentally. Therefore, the computational approach of the so-called CALPHAD method is very useful to understand the transfer of phosphorus from slag to metal and to enhance this reaction. In the present investigation, a theoretical study of the reduction behavior of phosphorus in slag was carried out at much lower temperatures using the recently developed thermodynamic database in the FactSage program. The calculated results showed reasonable accordance with the experimental data; namely, the thermodynamic database could be applied successfully to higher temperature reactions. The current study found that higher temperature and high $SiO_2$ concentration are favorable for the recovery of phosphorus from slag.

Synthesis and refining of fine hexagonal boron nitride powders by carbothermic method (Carbothermic 법에 의한 보론나이트라이드의 합성 및 고순도화)

  • Jee, Mi-Jung;Choi, Byung-Hyun;Kim, Sei-Ki;Lee, Mi-Jai;Lee, Dae-Jin
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2007.06a
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    • pp.305-305
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    • 2007
  • 고경도 및 내침식재료가 새로운 기계구조 및 기계 절삭공구재료로서 각광을 받고 있으며 질화붕소(BN)는 고융점, 고경도의 물리적 특성으로 다이아몬드 대체 물질로 주목되고 있다. 원하는 질화붕소의 합성을 위해서는 출발 원료와 합성법에 의존하는 것으로 보고되고 있다. 본 연구에서는 붕소 산화물과 환원제로써 활성 탄소를 출발 원료로 하였으며 치환제로써 질소를 사용하여 기상 반응로에서 질화붕소를 합성하였다. 합성된 시료는 XRD, SEM, PSA 등으로 물성을 측정하였고 합성 변수에 따라 순도의 차이를 보였으며, 본 연구를 통하여 최적의 합성 조건을 제시할 수 있었다.

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