• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.3
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• pp.310-316
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• 2020

In this study, the stability and EMP shielding performance of metal-based industrial by-products aggregates with excellent conductivity and easy procurement to be used as concrete aggregates for EMP shielding are evaluated. The industrial by-products are electronic-arc-furnace oxidizing slag, copper smelting slag, and ferro-moldibdenum. The composition analysis of aggregates and aggregate stability are evaluated. As a result of the experiment, ferro-moldibdenum is shown to have l ow stability as an aggregate due to its high Free-CaO. The remaining aggregates are evaluated to be safe to use as aggregates for concrete. In addition, industrial by-products aggreagate-specimens excluding ferro-moldibdenum are shown higher compressive strength than the plain specimen. The recycle aggregates, electronic-arc-furnace oxidizing slag and copper smelting slag, are shown excellent EMP shielding performance, the EMP shielding performance is expected to increase if the average particle diameter of the aggregate is small or evenly distributed.

• Resources Recycling
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• v.26 no.1
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• pp.37-42
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• 2017

It has been reported that aqueous indirect carbonation process of calcium silicate mineral could be one of the most promising methods for $CO_2$ sequestration. The process consists of two main steps, extraction of Ca from calcium silicate and carbonation of the extracted solution by $CO_2$. Many types of acids such as HCl and $HNO_3$ can be used in the extraction step of the process. In the case of using aqueous acetic acid solution as the extraction solvent, acetic acid can be reproduced at the carbonation step of the extracted solution by $CO_2$ and recycled to extraction step for reuse it. Industrial by-products such as iron and steel slags are potential raw materials of the indirect carbonation process due to their high contents of calcium silicate. In this study, in order to examine the extraction efficiency of domestic electric arc furnace steel slag by aqueous acetic acid solution, extraction experiments of the slag were performed by using the aqueous acetic acid solutions of varying extraction conditions ; acetic acid concentrations, extraction temperatures and times.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.3
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• pp.115-122
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• 2019

Electric arc furnace dust (EAFD), which is a dust waste generated in the steel manufacturing process, contains heavy metals. Recently, researches of recycling a large amount of valuable metals such as zinc and iron in EAFD are being actively carried out. In this study, EAFD is used as a substitute for cobalt in blue ceramic pigments without any pretreatment. Then, the synthesized blue ceramic pigment using EAFD was micronized and formulated as a ceramic ink for inkjet printer. The particle size distribution, crystal structure and color characteristics during the micronization process were investigated for the development of ceramic ink. $Co_{0.75}Zn(EAFD)_{0.25}Al_2O_4$ ceramic pigments showed excellent blue coloric properties and monomodal distribution through micronization process. The average particle size of $Co_{0.75}Zn(EAFD)_{0.25}Al_2O_4$ ceramic pigments after 3 hours of milling was $0.271{\mu}m$, which is smaller than $0.303{\mu}m$, which is the average particle size of $CoAl_2O_4$ ceramic pigments without EAFD after 5 hours of milling. Especially, it was confirmed that $Co_{0.75}Zn(EAFD)_{0.25}Al_2O_4$ ceramic pigments showed a color difference (${\Delta}E{^*}_{ab}$) value of 5.67, which smaller than ${\Delta}E{^*}_{ab}$ value of $CoAl_2O_4$ during micronization. These results show that EAFD can be used as a raw material for a blue ceramic pigment by replacing expensive cobalt without any pretreatment.

• Journal of Ocean Engineering and Technology
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• v.11 no.3
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• pp.56-68
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• 1997

This work was intended to study the effect of a partial pressure ratio and a total pressure of reactive gases on the properties of TiC$_{x}$N$_{1-x}$ . coated layer. In this regard, various TiC$_{x}$N$_{1-x}$ coatings were synthesized with C2112 and N2 Mixture gas of different compositions by Arc Ion Plating process which has been highlighted for an industrial purpose. It was revealed from colors and X-ray diffraction patterns that the concentration of carbon of a TiC$_{x}$N$_{1-x}$ coating increases with a partial pressure ratio (PC$_{2}$H$_{2}$/PN$_{2}$) as well as a total pressure Of $C_{2}$H$_{2}$ and N$_{2}$ mixture gas. Accordingly, the hardness of TiC$_{x}$N$_{1-x}$ coated layer increased but the adhesion to the substrate of SKH 51 was degraded. On the other hand, the deposition rate was independent of a partial pressure ratio and a total pressure of mixture gas. It was found that a uniform gas distribution is critical for an industrial application since the composition of a coating depends strongly on the location of a substrate inside of the furnace. As a result of milling tests with different TiC$_{x}$N$_{1-x}$ coated end mills, the one which has a low carbon concentration was better than others studied in this work.d in this work.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.111.2-111.2
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• 2011

야금학적 방법을 통한 태양전지용 실리콘 제조를 위하여 아크로(Arc furnace)에서 제조된 용융 상태의 금속급 실리콘을 슬래그와 직접 반응시켜 불순물을 제거하는 공정에 관한 연구를 수행하였다. 이를 위해 아크로와 고주파 유도용해로(High-frequency induction furnace)를 이용하여 금속급 실리콘을 제조와 정련 특성 실험을 수행하였다. 본 연구에서 금속급 실리콘을 제조하기 위한 장비로 150kW급-DC 아크로와 300kW급-AC 아크로를 사용하였다. 원재료로 규석, 코크스(Cokes), 숯, 그리고 우드칩(Wood chip)을 실험 비율에 맞춰 아크로 내부에 장입하고, 이를 용융환원 방법을 통해 반응을 시켰다. 이때 생산된 금속급 실리콘의 순도는 약 99.2~99.8% 이었으며, 원재료의 순도, 장입 비율 및 아크로 운전 특성에 따라 편차가 있다. 아크로에서 생산된 금속급 실리콘의 경우 인(phosphorus), 붕소(boron)를 다량 함유하고 있고, 이를 제거하기 위하여 50kW급 고주파 유도용해로 장비를 사용하여 슬래그 정련 실험을 수행하였다. 슬래그 정련시 사용한 성분은 SiO2, CaO 그리고 CaF2 이며, 금속급 실리콘과 슬래그의 질량비 및 반응 시간에 따른 실리콘 불순물 특성을 평가하였다. 실험결과 인과 붕소는 각각 1 ppm 이하, 5 ppm 이하 였으며, 칼슘을 제외한 대부분의 금속 불순물의 경우 0.1~0.2% 임을 확인하였다.

• Transactions of Materials Processing
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• v.15 no.8 s.89
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• pp.603-608
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• 2006

The main purpose of the present study has been placed on investigating the mechanical properties and microstructures of C-Si-Mn-V steels for cold forming manufactured by controlled rolling and cooling technology. The steels were manufactured in electric arc furnace (EAF) and casted to $160{\times}160mm$ billet. The billets were reheated in walking beam furnace and rolled to coil, the stocks were rolled by Controlled Rolling and Cooling Technology (CRCT), so rolled at low temperature by water spraying applied in rolling stage and acceleratly cooled before coiling. Rolled coils were cold drawed to the degree of 16%, 27% of area reduction respectively without heat treatment. Microstructual observation, tensile test, compression test and charpy impact tests were conducted. The mechanical properties of the steels were changed by area reduction of cold drawing and it is founded that there are optimum level of cold drawing to minimize compression stress for these steels. From the result of this study, it is conformed that $80kg_{f}/mm^{2},\;90kg_{f}/mm^{2}$ grade high strength microalloyed steel for cold forming are developed by accelerated cooling and optimum cold drawing.

• 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.

• Resources Recycling
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• v.23 no.1
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• pp.58-63
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• 2014

Variety of volatile materials is present in crude-Zinc oxide recovered from EAFD(Electric arc furnace steel dust). Commonly, it is purified by oxidizing roasting. In this study, spherical each specimen prepared crude-zinc oxide like 1~3 mm and 10 mm was tested in vertical tube furnace at the temperature range $600^{\circ}C$ to $1200^{\circ}C$ in oxidizing atmosphere. Oxidizing roasting properties of zinc oxide were investigated using XRD, XRF and ICP-OES. At temperature blow $950^{\circ}C$ volatilization rate were remarkably low. As the temperature increases, the concentration of Zn increased and the concentration and XRD peaks of impurities decreased. The result indicated that volatilization rate depended on specimen size and roasting temperature.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.11
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• pp.952-957
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• 2003

We propose how to translate relay circuits to the EMFGs(Extended Mark Flow Graphs) formally and analyze the original one by using the mark flow of it. Firstly, the concepts of the output condition, the output-on condition and the output-off condition are introduced in the relay circuits. These can be used to find the structure and the operation of respective relay outputs but the sequential operations of them cannot be obtained from these. Secondly, a relay circuit is translated to the corresponding EMFG as the all output-on conditions and all output-off conditions of it are translated to EMFGs. For the adequate translation, the condition arc and the concepts of the generation transition and the degeneration transition are introduced, and the duality for the simplification of the result. Thirdly, we analyze the operation of the original circuit by analyzing the mark flow of the resulting EMFG. We can achieve easy and fast analysis based on the EMFG's operation algorithm. Finally, we apply these to the relay circuit for an electric furnace and analyze its operation with the mark flow of the resulting EMFG. The formal translation from relay circuits to EMFGs makes the analysis easy so that these results can be used to design, modelling, the fault detection and the maintenance.

• Journal of Electrical Engineering and Technology
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• v.3 no.3
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• pp.314-319
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• 2008

Power quality simulation plays an important role in many practical cases, for example, when deciding the capacity of the related mitigation devices, assessing the influence of installing a nonlinear load in the distribution part, dissolving the quality issues between utilities and customers, and so on. For these purposes, many dedicated tools have been used in order to assess the level of quality distortions by various kinds of PQ indices. However, there are few modules that can accurately simulate the flicker phenomenon, that is, $P_{st}$ and the nonlinear and chaotic behavior of the electrical arc furnace, which is one of the representative nonlinear loads. This paper deals with the useful and simple modules for the voltage flicker simulation in the distribution and transmission level under the environment of Matlab/Simulink. With these modules, the various conditions of distribution systems and the capacities of arc furnaces with the chaotic characteristic can be easily taken into account.