• Proceedings of the Korean Nuclear Society Conference
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• 2001.10a
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• pp.257.2-257
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• 2001

• 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.

• 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.

• 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.

• 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.

• Resources Recycling
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• v.27 no.2
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• pp.68-76
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• 2018

EAF (Electric arc furnace) dust is an important secondary resource such as zinc, lead, and iron. Recycling of EAF dust is benefit to solving disposal and environmental problems caused by the heavy metals entrained in the dust. In this study, pyrometallurgical treatment technology of EAF dust reviewed for the improvement of conventional process and development of new process. The existing technologies categorized into four groups: those by rotary kiln process, rotary hearth furnace (RHF) process, shaft type process, and reduction smelting process. The product of these processes are ZnO and Fe or slag as a waste. Their mechanisms for the production of ZnO from EAF dust were carbothermic reduction and oxidation of zinc gas with air.

• 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.

• Resources Recycling
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• v.19 no.1
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• pp.21-26
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• 2010

In order to understand the microwave carbothermic reduction of steelmaking slag to recover Fe, the effects of gas atmosphere and carbon addition on the carbothermic reduction behavior of CaO-$SiO_2$-FeO slag were investigated. It was found that the maximum temperature and the reduction rate were higher in air than in nitrogen atmosphere. In addition, under air atmosphere, the maximum temperature and the reduction rate were increased by increasing the amount of additive carbon. When the carbon equivalent is 5, the maximum temperature reached as high as 1800K and the reduction rate was approximately 90%. As the Carbon equivalent increased further, the maximum temperature and the reduction rate did not change.

• Resources Recycling
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• v.28 no.3
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• pp.59-67
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• 2019

This study was conducted to fabrication pig iron containing copper and to reduce sulfur content pig iron. Roasting test was conducted for 1 ~ 9 hours at each temperature of $500^{\circ}C$, $700^{\circ}C$, and $900^{\circ}C$. In addition, the effect of oxygen partial pressure with 0.5, 0.8, and 1 atm was carried out for 30 minutes at $900^{\circ}C$. It was found that there is no effect to reduce sulfure in pig iron through roasting and oxygen partial pressures. The addition of CaO with 15 wt.% was found to reduce sulfur content up to 0.001 wt.%. The suitable temperature and reactive time for carbothermic reduction were $1600^{\circ}C$ and 30 minutes which shows the highest recovery rate of iron from the copper slag.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2014.11a
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• pp.91-91
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• 2014

주석함유 2차 공정 부산물인 양극 슬라임내의 금속을 회수하기 위하여 탄소환원반응을 통해 금속 회수에 미치는 공정변수의 영향을 조사하였다. 열역학 모델링과 금속환원 실험결과, 환원 온도와 고체 환원제인 코크스(cokes)에 공정 변수에 따라 금속으로 환원이 될 수 있음을 확인하였다.