• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2006.05a
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• pp.150-155
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• 2006

제강공정에서 발생되는 $CaO-Al_{2}O_{3}-SiO_{2}$계 조성을 갖는 2 차 정련슬래그 (래들 슬래그)를 이용하여 하수슬러지용 고화재개발 및 하수슬러지 고화체의 물성에 관한 연구를 수행하였다. 래들슬래그는 냉각과정에서 분화되는 성질이 있어 냉각후 분말상의 슬래그가 만들어진다. 분말상 슬래그의 주 결정상은 $12CaO{\cdot}7Al_{2}O_{3}$ 및 $2CaO{\cdot}SiO_{2}$로 구성되어 있다. $12CaO{\cdot}7Al_{2}O_{3}$ 상은 속경성 시멘트의 특징이 있다. 또한 $CaSO_{4}$와 혼합사용시 ettringite 상을 형성시켜 하수슬러지의 함수율 저감효과 및 강도발현 효과가 우수한 결과를 얻었다. $Cl^{-}$ 이온의 고정화면에서는 고화재중 래들슬래그의 혼합비가 높을수록 고화체 구조내에 $Cl^{-}$ 이온이 고정화되어 용출량은 감소하였다. 고화재로서 제강부산물을 사용하기 때문에 경제성이 있으며, $Cl^{-}$ 이온 함량이 높은 하수슬러지 고화재로서의 재활용이 기대된다.

• Journal of Korea Foundry Society
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• v.15 no.2
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• pp.175-183
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• 1995

It is difficult to remove such interstitial impurities as sulfur, oxygen, hydrogen and carbon in Fe-Ni alloys. Thermodynamic and kinetic studies were carried out on the behavior of hydrogen gas, oxygen gas, Si, Al and slag, and the reaction time by the $Ar/Ar-H_2$ plasma and electron beam melting. After the addition of Al, Si, they were melted by Ar plasma with reaction time changed. 80%Ni-Fe alloys showed a better deoxidation than 36%Ni-Fe alloys. At $Ar-H_2$ plasma melting, the deoxidation was significant. In the case of the electron beam melting, the residual oxygen was higher than in Ar plasma melting because electron beam melting temperature was lower than that of Ar plasma. For the decaburization, it was melted by $Ar-O_2$ plasma melting, which could remove effectively carbon by activated oxygen in plasma. We added slag to Fe-Ni alloys for the desulfurization. As the result of this experiments, the amount of residual sulfur was not changed according to the slag ratio and reaction time.

• Advances in concrete construction
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• v.11 no.3
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• pp.219-229
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• 2021

In recent years, geopolymer cements, have gained significant attention as an environmental-friendly type of cement. In this experimental research, effects of different alkaline activator solutions and variations of associated parameters, including time of addition, concentration, and weight ratio, on the mechanical strengths of Granulated Ground Blast Furnace Slag (GGBFS)-based Geopolymer Concrete (GPC) were investigated. Investigation of the effects of simultaneous usage of KOH and NaOH solutions on the tensile and flexural strengths of GGBFS-based GPC, and the influence of NaOH solution addition time delay on the mechanical strengths is among the novel aspects investigated in this research. four series of mix designs and corresponding specimen testing is conducted to study different parameters of the active alkali solutions on GPC mechanical strengths. The results showed that addition of NaOH to the mix after 3 min of mixing KOH and Na2SiO3 with dry components (1/3 of the total mixing duration) resulted in the highest compressive, tensile and flexural strengths amongst other cases. Moreover, increasing the KOH concentration up to 12 M resulted in the highest compressive strength, while weight ratio of 1.5 for Na2SiO3/KOH was the optimum value to achieve highest compressive strengths.

• Journal of Conservation Science
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• v.36 no.3
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• pp.162-177
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• 2020

Research was conducted to characterize the copper production and smelting process with 11 copper smelting by-products (copper slag and copper crucible) excavated from the NA and LA areas at the Gwanbuk-ri archeological site in Buyeo. Scanning electron microscopy-energy dispersive spectroscopy, wavelength dispersive X-ray fluorescence, X-ray diffraction, and Raman microspectroscopy were employed in the analysis. The research results reveal that the copper slag from Gwanbuk-ri contained silicate oxide, magnetite, fayalite, and delafossite, which are typical characteristics of crucible slag and refined slag. The outward appearance and microstructure of the slag were grouped as follows: 1. glassy matrix + Cu prill, 2. glassy matrix + Cu prill + magnetite, 3. silicate mineral matrix + Cu prill, 4. crystalline (delafossite and magnetite) + amorphous (Cu prill), 5. magnetite + fayalite, and 6. slag from slag. The copper slags from Guanbuk-ri were found to contain residues of impurities such as SiO₂, Al₂O₃, CaO, SO₄, P₂O₅, Ag₂O, and Sb₂O₃ in their microstructure, and, in some cases, it was confirmed that copper, tin and lead are alloys. These results indicate that refining of intermediate copper(including impurities) and refining of alloys of copper(including impurities) - tin and refining of copper(including impurities) - tin - lead took place during the copper production process at Gwanbuk-ri, Buyeo.

• Resources Recycling
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• v.15 no.2 s.70
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• pp.3-9
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• 2006

As a basic study on the conversion of molten converter slag to the ordinary portland cement, the effects of $Al_{2}O_{3}$ addition on the interface reaction between solid CaO and molten converter slag has been studied. Alumina added converter slag whose basicity was controlled to 1 and 2 was melted and hold for 30 minutes in MgO crucible at $1500^{\circ}C$. Then sintered CaO pellet heated at the same temperature was dipped into the molten slag and held for 30minutes. After the reaction, the crucible was cooled in air and the specimen was cut off to the horizontal direction of the crucible. The dissolution rate of CaO pellet with the addition of $Al_{2}O_{3}$ was measured by the change of the radius or sintered CaO pellet and the interface layer was observed by SEM/EDX. As a result. At the basicity 2 slag, thickness of created $C_{3}S$ layer increased 3.5 times and quantity of $C_{6}AF_{2}\;or\;C_{4}AF$ phase increase 2 times than baisicy 1 slag.

• Journal of the Mineralogical Society of Korea
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• v.20 no.4
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• pp.267-275
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• 2007

Melting slag generated from municipal-incinerator ash contains lots of impurities which have adverse effects on zeolite synthesis. These impurities are detrimental to zeolite synthesis, and the yield and purity of zeolite was decreased. And thus its performance is lowered. In melting slag, there are lots of components such as $Fe_2O_3$, FeO and CaO. To remove these impurities, we treated the melting slag with hydrochloric acid at initial pH 1, 3, 5, and 7. After the treatment, the $SiO_2,\;Fe_2O_3,\;and\;TiO_2$ ratios increased, but the $Al_2O_3,\;FeO,\;CaO,\;Na_2O$ and MgO ratios decreased. We reacted these treated slag in a NaOH solution under hydrothermal conditions at $80^{\circ}C$. The hydrothermal products from the slag and the slag treated at pH 7 and pH 5 were determined to be tobermorite, whereas those at pH 3 and pH 1, Na-P1 and Na-X zoelite respectively. CaO was found to inhibit the synthesis of zeolite.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.43.2-43.2
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• 2010

In this study, metallurgical grade (MG) silicon with 99% purity produced by arc furnace process was systematically investigated for slag refining. The most problematic impurities to remove from MG silicon are boron (B) and phosphorus (P). To remove B and P from MG-silicon, we used synthetic slag in the molten state. MG-silicon with synthetic slag of CaO, $SiO_2$, and $CaF_2$ was melted using by high-frequency induction furnace with electrical output of 50kW. Specimens prepared by various refining process conditions(holding time, mixture ratio) were inspected by combined analysis of ICP-MS and XRF. With this approach, B has been reduced to <5ppm, P to <1ppm and other impurities to 0.1~0.2% except for Calcium. Calcium has been increased from 17ppm to 1500ppm. Problem of calcium contamination will be resolved by additional refining processes.

• Journal of the Korea Institute of Building Construction
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• v.2 no.2
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• pp.145-150
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• 2002

The hydration of cement paste occurs when the cement is miked with water. During the hydration, hydration heat causes the thermal stress depending on the site of concrete and the cement content. Especially in the high-strength concrete, we must give care to the concrete due to its large cement content. In this study conduction calorimeter and concrete insulation hydration heat meter were used to investigation the hydration heat characteristics of cement and concrete. To reduce hydration heat of high-strength concrete, several types of replacement of fly-ash and blast-furnace slag powder were used in this experiment. As a result of this study, it was found that hydration heat of high-strength concrete was reduced by replacement of fly-ash and blast-furnace slag powder. In case of high-strength concrete using blast-furnace slag powder, the max-heat arrival time was delayed but an effect of heat reduction was lower than a case of high-strength concrete using fly-ash, because it was considered that the heat-dependence property of blast-furnace slag powder was higher than that of fly-ash.

• Journal of Conservation Science
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• v.3 no.1 s.3
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• pp.13-18
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• 1994

Chemical analysis and metallographic observations of the iron slag were carried out in an attempt to estimate the old iron-making process. The slag containing $9.3\%\;TiO_2$ without Cu indicates that the ore used for smelting was sand iron, not rock ore. The phases identified in the slag were $ulv\ddot{o}spinel$, magnetite, $w\ddot{u}stite$, fayalite etc. This also supports the fact that the smelted ore was iron sand. The total amount of Fe and slag-making components$(=SiO_2+Al_2O_3+MgO+CaO)$ were $40.7\%\;and\;36.1\%$, respectively. These values were average ones found in the old slags formed in the ancient iron-making process. Assuming that $TiO_2$ in the ore combines with FeO, resulting in the formation of $ulv\ddot{o}spinel$, the estimated temperature of smelting was found to be about $1200^{\circ}C$.

• International Journal of Highway Engineering
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• v.15 no.6
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• pp.69-78
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• 2013

PURPOSES : In this study blast furnace slag, an industrial byproduct, was used with an activating chemicals, $Ca(OH)_2$ and $Na_2SiO_3$ for carbon capture and sequestration as well as strength development. METHODS : This paper presents the optimized mixing design of Carbon-Capturing and Sequestering Activated Blast-Furnace Slag Mortar. Design of experiments in order to the optimized mixing design was applied and commercial program (MINITAB) was used. Statistical analysis was used to Box-Behnken (B-B) method in response surface analysis. RESULTS : The influencing factors of experimental are water ratio, Chemical admixture ratio and Curing temperature. In the results of response surface analysis, to obtain goal performance, the optimized mixing design for Carbon-Capturing and Sequestering Activated Blast-Furnace Slag Mortar were water ratio 40%, Chemical admixture ratio 58.78% and Curing temperature of $60^{\circ}C$. CONCLUSIONS : Compared with previous studies of this experiment is to some extent the optimal combination is expected to be reliable.