• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.1
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• pp.128-135
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• 2006

Steel slag (divided into electric arc furnace slag and convener slag) is being produced by millions of tons per every year in many industrial countries. About 6.5 million tonnes of steel slag is produced yearly as an industrial by-product in Korea. Generally natural aggregate is relatively stable and does not enter into complex chemical reactions with water. Unfortunately, however. steel slag aggregate contains a small amount of free lime. The hydration of free lime makes steel slag aggregate unstable and liable to expand. In this paper, firstly, several aging methods are used in order to decrease the volume expansion of electric arc furnace slag, that is stabilization. The volume expansion of electric arc furnace slag is formulated from the experiment. From the formula, the residual expansibility is predicted with immersion expansion. Compressive strength of concrete with electric arc furnace slag has relation with the residual expansibility in slag aggregate.

• Journal of the Korean Ceramic Society
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• v.36 no.1
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• pp.30-35
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• 1999

For dolomite clinkers used as stamp materials, the corrostion behavior of those by slag was inverstigated between 1550$^{\circ}C$ and 1650$^{\circ}C$. Fe2O3 among slag components was selectively penetrated into the grain boundaries of dolomite clinkers. In hot face, the magnesioferrite was preferentially formed by Fe2O3 component contained in dolomite clinker rather than Fe2O3 of slag. The corrosion steps of dolomite clinkers by slag were found as follows ; (1) The dicalciumferrite was formed by the reaction of the calcia within dolomite clinkers with Fe2O3 of slag. (2) The magnesia within dolomite clinkers reacted with the dicalciumferrite to from magnesioferrite and the residual calcia within dolomite clinkers reacted with the dicalciumferrite to form magnesioferrite and the residual calcia was dissolved into slag. (3) The magnesioferrite was corroded by CaO-SiO2 compounds of slag. With the temperature of slag increased, the magnesioferrite layer in hot face was decreased for dolomite clinker without Fe2O3 while the layer thickness and grain sizes of magnesioferrite was increased for dolomite clinker with Fe2O3.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.692-697
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• 2004

This study is on the increasement of strength about soft ground improvement material using waste residual(paper fly ash, coke ash, slag) by fire. Through this study the authors have analyzed the strength improvement of mixed soft silty sand with improvement materials. The strength of mixed soils with high mixture ratio and more curing days increased. But CA-30(cokes 60%) make more low strength improvement than others. Therefore the authors find out that paper fly ash+cokes, paper fly ash+slag or cokes+slag improvement material is more effect in improvement of soft silty sand than cokes+cenlent. And Ettringite reaction is free mixed soils with more than two materials.

• Proceedings of the KIEE Conference
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• 2002.11c
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• pp.92-95
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• 2002

A study on the system automation for the nitrogen splash slag coating in Basic Oxygen Blowing Furnace (BOF) is described. The engineers are trying to do their best efforts to increase the life of converter lining by developing improved refractory material and optimal operation techniques in the steel plants, A new slag coating method is needed to reduce the erosion rates of the refractory. In the current slag costing method, the BOF was swung back and forth. The new method uses the oxygen lance to blow the residual slag to the walls and cone of the converter. The nitrogen gas is used for blowing. This method is developed based on the automation process at factory in POSCO dated on the May 1998. The test results of nitrogen splash slag coating system for the BOF at POSCO are show to show the effectiveness of the system.

• Economic and Environmental Geology
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• v.55 no.4
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• pp.377-388
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• 2022

Laboratory-scale experiments were performed to identify the As removal mechanism of the residual slag generated after the mineral carbonation process. The residual slags were manufactured from the steelmaking slag (blast oxygen furnace slag: BOF) through direct and indirect carbonation process. RDBOF (residual BOF after the direct carbonation) and RIBOF (residual BOF after the indirect carbonation) showed different physicochemical-structural characteristics compared with raw BOF such as chemical-mineralogical properties, the pH level of leachate and forming micropores on the surface of the slag. In batch experiment, 0.1 g of residual slag was added to 10 mL of As-solution (initial concentration: 203.6 mg/L) titrated at various pH levels. The RDBOF showed 99.3% of As removal efficiency at initial pH 1, while it sharply decreased with the increase of initial pH. As the initial pH of solution decreased, the dissolution of carbonate minerals covering the surface was accelerated, increasing the exposed area of Fe-oxide and promoting the adsorption of As-oxyanions on the RDBOF surface. Whereas, the As removal efficiency of RIBOF increased with the increase of initial pH levels, and it reached up to 70% at initial pH 10. Considering the PZC (point of zero charge) of the RIBOF (pH 4.5), it was hardly expected that the electrical adsorption of As-oxyanion on surface of the RIBOF at initial pH of 4-10. Nevertheless it was observed that As-oxyanion was linked to the Fe-oxide on the RIBOF surface by the cation bridge effect of divalent cations such as Ca²⁺, Mn²⁺, and Fe²⁺. The surface of RIBOF became stronger negatively charged, the cation bridge effect was more strictly enforced, and more As can be fixed on the RIBOF surface. However, the Ca-products start to precipitate on the surface at pH 10-11 or higher and they even prevent the surface adsorption of As-oxyanion by Fe-oxide. The TCLP test was performed to evaluate the stability of As fixed on the surface of the residual slag after the batch experiment. Results supported that RDBOF and RIBOF firmly fixed As over the wide pH levels, by considering their As desorption rate of less than 2%. From the results of this study, it was proved that both residual slags can be used as an eco-friendly and low-cost As remover with high As removal efficiency and high stability and they also overcome the pH increase in solution, which is the disadvantage of existing steelmaking slag as an As remover.

• Resources Recycling
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• v.33 no.2
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• pp.46-53
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• 2024

The residual heat and high CaO content present in the slag remaining in the ladle after the completion of continuous casting in the electric arc furnace (EAF) steelmaking process have been utilized to reduce power consumption and lime usage in the ladle furnace (LF) process. However, if the timing of such processes does not align with the LF and continuous casting operations, the recycling rate will decrease. To increase the slag recycling rate, the effect of ladle slag recycling methods, specifically pouring ladle slag into the slag pot in advance for subsequent recycling, on LF operations was analyzed. The slag liquefaction rate was calculated using the thermodynamic program Factsage 8.3 for ladle molten slag recycling methods. By applying each of the 10 heats operations for the ladle slag recycling methods, the desulfurization ability and LF operation performance were compared. It was found that when slag was immediately recycled into the ladle after continuous casting was completed, power consumption decreased by 0.3 MWh, LF operation time was shortened by 1.2 minutes, and the desulfurization rate increased by 5.8%.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.3
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• pp.205-211
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• 2000

This study was conducted to evaluate the residual effects of basic oxygen furnace (BOF) slag applied in rice paddy fields as soil conditioner one year before. The experimental fields of Lim et al. (2000) located in Youjung and Nampyung were used for this purpose. Both variety (Oryza sativa L. cv. Dongjinbyeo) and cultural practices were the same as those in Lim et al. (2000). Soil chemical properties, plant height, number of tillers per plant, yield and yield components were observed. The temporal variation of treatment mean value in soil chemical properties appeared to be similar trends in both Youjung and Nampyung experimental fields. Soil pH and Ca content were still significantly higher than those in control treatment up to July of the second season, but decreased progressively as time passed. However, the effects lasted longer as slag rate became higher. BOF slag seems to have residual effects as a soil conditioner or Ca fertilizer in soil for two years. BOF slag rate of $4Mg\;ha^{-1}$ raised soil pH almost the same as lime rate of $2Mg\;ha^{-1}$. Content of $SiO_2$ in soil applied slag appeared to be higher compared with control. Fe and Mg content in soil with slag treatment was significantly higher than that of control in 1997, but it was almost the same level as that of control in 1998. In YouJung experimental field, rough rice yield of slag teatment became higher as slage rate incresed. Slag rate of $12Mg\;ha^{-1}$ showed the highest rough rice yield of $5,400kg\;ha^{-1}$ among treatment, which was 14% higher than that of control with $4,720kg\;ha^{-1}$. Slag rate of $12Mg\;ha^{-1}$ showed relatively higher plant height and higher number of tillers at the early growth stage compared with other treatments. In NamPyung experimental field, rough rice yield was the highest at the plot of lime rate $2Mg\;ha^{-1}$ and became higher as slag rate increased. There were no significant differences in rough rice yield between lime treatment and slag treatments. Slag rate of $12Mg\;ha^{-1}$ showed the highest rough rice yield of $7,170kg\;ha^{-1}$ among slag treatment, which was 8% significantly higher than that of control with $6,670kg\;ha^{-1}$. Slag rate of $12Mg\;ha^{-1}$ showed relatively slower growth in plant height at the early growth stage, but superior growth at the later growth stage, and significantly higher number of spiklets per panicle and 1000-grain weight than that of control.

• 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.

• Journal of Environmental Science International
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• v.26 no.8
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• pp.955-966
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• 2017

Amendment of multi-binders was employed for the immobilization of metal(loid)s in field-contaminated soils to reduce the leaching potential. The effect of different types of multi-binders (lime/diammonium phosphate, diammonium phosphate/ladle slag and lime/ladle slag) on the solidification/stabilization of metal(loid)s (Pb, Zn, Cu and As) from the smelter soil and mine tailing soil were investigated. The amended soils were evaluated by measuring Toxicity Characterization Leaching Procedure (TCLP) leaching concentration of metal(loid)s. The results show that the leaching concentration of metal(loid)s decreased with the immobilization using multi-binders. In terms of TCLP extraction, the mixed binder was effective in the order of lime/ladle slag > diammonium phosphate/ladle slag > lime/diammonium phosphate. When the mixed binder amendment (0.15 g lime+0.15 g ladle slag for 1g smelter soil and 0.05 g lime+0.1 g ladle slag for 1 g mine tailing soil, respectively) was used, the leaching concentration of metal(loid)s decreased by 90%. However, As leaching concentration increased with diammonium phosphate/lime and diammonium phosphate/ladle slag amendment competitive anion exchange between arsenic ion and phosphate ion from diammonium phosphate. The Standard, Measurements and Testing programme (SM&T) analysis indicated that fraction 1 (F1, exchangeable fraction) decreased, while fraction 4 (F4, residual fraction) increased. The increased immobilization efficiency was attributed to the increase in the F4 of the SM&T extraction. From this work, it was possible to suggest that both arsenic and heavy metals can be simultaneously immobilized by the amendment of multi-binder such as lime/ladle slag.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.4
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• pp.414-420
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• 2017

The thermal characteristics of concrete fabricated with blast furnace slag were investigated in this paper. Test parameters included water-binder ratio and the content of furnace slag. Experimental program were performed to measure mechanical properties including compressive strength and split tensile strength under high-temperature thermal cycling, and to measure thermal properties including thermal conductivity and specific heat. Test results showed that the residual compressive strength of mixtures with blast furnace slag was greater than that of mixture without blast furnace slag. In addition, thermal conductivity of mixtures with blast furnace slag was greater than that of mixtures without blast furnace slag. It indicates that blast furnace slag was favorable for charging and discharging in thermal energy storage system. Test results of this study would be used to design concrete module system of thermal energy storage.