• Journal of the Korean GEO-environmental Society
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• v.12 no.7
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• pp.31-37
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• 2011

Only a few studies have been conducted using reduced slag as recycled material. The reduced slag in electric furnace is produced as a by-product in making a steel and a few applications of the reduced slag as expensive additives and bonding materials or as the stabilized soils was reported. The purpose of this study is to present the feasibility of the reduced slag as recycled material, especially, in a field of civil engineering. In order to achieve the purpose experiments such as SEM and XRF analysis was conducted for the reduced slag in electric furnace. Based on the results various geotechnical experiments were conducted to know engineering properties of slag-soil mixtures. Weathered soils and clay are mixed with reduced slag for various ratios. As the ratio of reduced slag to weathered soil increases, the maximum dry unit weight of the mixture decreased with increasing optimum moisture content. The results indicates that there is no effect on a reduced slag by compaction efforts. The shear strengths of the weathered soil-slag mixtures are slightly higher or similar to those of weathered soils. The permeability of the weathered soil-slag mixtures is similar to that of silty or sandy soils. Therefore, it is possible to use the mixtures as embankment or backfill materials in the fields. The unconfined strength of the mixtures of reduced slag and clay is higher than that of clay and it tends to increase with the curing time. Therefore it can be used to improve the soft ground.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.6
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• pp.841-849
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• 2012

The effluent quality of phosphorus is strengthened by the national standard to conserve water resources to lessen the eutrophication threat. The soluble phosphate in the wastewater effluent can be removed using the converter slag as solid waste produced through the steel making process. The experiments for removal efficiencies and removal constants were performed for this research with the artificial wastewater following several different conditions, particle size, phosphate concentration and initial pH. The correlation coefficients of Freundlich adsorption isothem were 0.9505 for $PS_A$, 0.9183 for $PS_B$, respectively. The removal efficiency was 87-94 % for $PS_A$ and 90-96 % for $PS_B$ respectively. The pH of the wastewater was elevated to pH 11.8 for the initial pH 8.5, phosphate removal efficiency was the highest as 84 % ~ 98 %. In case of 10 mg/L of the intial phosphate, the removal efficiency was 96 ~ 98 %. The more initial pH increases, the higher the reaction rate constant is.

• Journal of Conservation Science
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• v.33 no.4
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• pp.297-312
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• 2017

In the ancient iron-making process, a slag former was often added so that iron and other minerals in the ore could be smoothly separated. However, there are insufficient data for judging whether a slag former was added. Thus, in this study, we conducted a smelting experiment to understand the material characteristics of a steel structure that differed depending on the addition of a slag former. It was found that the steel structure produced in the first experiment had a total Fe content of 39.45-52.94 wt%, which decreased to 34.89-38.92 wt% in the second and third experiments. CaO compounds such as calcite, gehlenite, and hercynite appeared, in addition to iron oxides, after the addition of a slag former. As a result of an assessment of whether a slag former was added by comparing the ratio between the components, it was found that the ratio of $CaO/SiO_2$ was 0.42. From a comparative analysis of $Al_2O_3/SiO_2$ and $CaO/SiO_2$, it was judged that the ratio of $Al_2O_3$ and $SiO_2$ can be utilized as an index to judge similar systems of smelting process (ore, furnace wall, and fuel).

• Journal of Soil and Groundwater Environment
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• v.20 no.7
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• pp.135-147
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• 2015

Remediation of metal(loid)s-contaminated sites is crucial to protect human and ecosystem. Solidification and stabilization of metal(loid)s by the binder amendment is one of the cost-effective technologies. In this study, metal (loid)s in various field-contaminated soils obtained from steel-making, metal refinery and mining tillage were immobilized by the application of single binders such as diammonium phosphate (DAP), lime, and ladle slag. The efficiency of solidification and stabilization was evaluated by Toxicity Characteristic Leaching Procedure (TCLP) and the Standard, Measurements and Testing programme of European Union (SM&T) extraction processes. In terms of TCLP extraction, the binder was effective in order of lime > DAP > ladle slag. All binders were highly effective in the immobilization of Pb, Zn, Cu, Ni, and Cd. The increased immobilization efficiency is attributed to the increase in the Step III and IV fractions of the SM&T extraction. Lime and ladle slag were highly effective in the immobilization of the metal(loid)s, however, As release increased with DAP due to competition between the phosphate originated from DAP and arsenate. A further study is needed for the better immobilization of multi metal(loid)s using binary binders.

• Resources Recycling
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• v.16 no.4
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• pp.10-16
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• 2007

As a basic study for reusing converter slag as slow-release potassium fertilizer by a sintering process, powdery converter slag and reagent grade $SiO_2\;and\;K_2CO_3$ were mixed with ball mill above 24 hours and sintered at $900^{\circ}C{\sim}1000^{\circ}C\;for\;10{\sim}60$ min. Basicity of the mixed powder was controlled to 0.7, 1.0 and 1.4 and content of $K_2O$ was fixed with 22 mass%. After sintering, property of the potassium fertilizer was investigated with X-ray diffraction pattern and ICP analysis. Also effects of basicity, sintering temperature and time on the making slow-release potassium fertilizer was investigated. Water solubility of KBO in sample were decreased with sintering time, temperature and decreased with basicity. Citric acid solubility of $K_2O$ were increased with basicity and decreased with sintering temperature.

• Resources Recycling
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• v.31 no.6
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• pp.44-51
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• 2022

In the steelmaking process using an electric arc furnace (EAF), light-burnt dolomite, which is a flux containing MgO, is used to protect refractory materials and improve desulfurization ability. Furthermore, a recarburizing agent is added to reduce energy consumption via slag foaming and to induce the deoxidation effect. Herein, a waste MgO-C based refractory material was used to achieve the aforementioned effects economically. The waste MgO-C refractory materials contain a significant amount of MgO and graphite components; however, most of these materials are currently discarded instead of being recycled. The mass recycling of waste MgO-C refractory materials would be achievable if their applicability as a flux for steelmaking is proven. Therefore, experiments were performed using a target composition range similar to the commercial EAF slag composition. A pre-melted base slag was prepared by mixing SiO₂, Al₂O₃, and FeO in an alumina crucible and heating at 1450℃ for 1 h or more. Subsequently, a mixed flux #2 (a mixture of light-burnt dolomite, waste MgO-C based refractory material, and limestone) was added to the prepared pre-melted base slag and a melting reaction test was performed. Injecting the pre-melted base slag with the flux facilitates the formation of the target EAF slag. These results were compared with that of mixed flux #1 (a mixture of light-burnt dolomite and limestone), which is a conventional steelmaking flux, and the possibility of replacement was evaluated. To obtain a reliable evaluation, characterization techniques like X-ray diffraction (XRD) analysis and X-ray fluorescence (XRF) spectrometry were used, and slag foam height, slag basicity, and Fe recovery were calculated.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.381-386
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• 2001

The dust generated from the electric arc furnace steel making process is classified as hazardous material by Korean Environmental Protection Acts, mainly because of the existence of water teachable Pb, Zn and Cd. Thus the treatment of EAF dust is being carried out to fulfill both the environmental aspect and recovery of valuable metals. To establish the proper process for recovering the valuable metals (Fe, Zn, Pb and Cd) and producing the non-toxic slag from EAF dust, using RAPID-10 system, feasibility study have been carried out. To find out the scale-up factor for designing the commercial scale EAF dust treatment process(capacity 50,000 ton EAF dust per year) entitled RAPID-50 system. The design and construction of RAPID-50 (RIST Arc Plasma Industrial Device) system for treating 50,000 ton of EAF dust per year is now undergoing. Overall plan for treating EAF dust generated in KOREA will be setup after successful operation (December, 2002) of RAPID-50 system.

• 보존과학연구
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• s.13
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• pp.37-58
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• 1992

Iron artifacts from Busǒ Sansǒng inffered to late Baikjae periodwere studied on the aspects of metallugy. These materials were the largest size ever since excavated. From the analytical results these artifacts were found to be pureiron system without impurities or hypo-eutectoid steel system in below 0.3% in carbon contents. From the content of phosphorus in the range of 0.03∼0.05% as aim purity it was shown that charcoal were used for making these iron artifacts from sponge iron not fusion method. By observing metallugical structure it was found that iron artifacts was manufactured by repetitive folding and hammering forging method and some by heating method for adding carbon with cool water. This method were to improve the quality of the soften steel to harden one. In addition to those above repetitive hammering method eliminated the nonferrous materials such as slag inclusion and remained relatively pure ferrite.

• Journal of the Korean Geosynthetics Society
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• v.17 no.1
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• pp.1-10
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• 2018

We conducted research to develop a solidification agent for the ground surface reinforcement method in which activator is fused by recycling pig iron slag, which is a byproduct generated in the steel making process. The purpose of this research is to solve the problems of surface soil by improving the strength and durability of foundation soil such as soil loss, settlement, sinkhole, etc. by recycling pig iron slag from disused or landfilled steelworks. For this purpose, the possibility of using pig iron slag as a solidification soil was evaluated by the compressive strength, elution test of harmful materials, permeability coefficient test. As a result of the compressive strength test, the values of the strength of the curing 28 days of the solidified soil having the solidification agent mixing ratio of 12% were found to be 0.93, 0.96 and 1.3 MPa, respectively, satisfying the required strength value of 1 MPa, In the case of permeability coefficients, the minimum values were $4.1{\times}10^{-8}$, $7.0{\times}10^{-7}$, and $1.7{\times}10^{-7}cm/sec$, respectively, at the solidification agent mixing rate of 12%. In addition, as a result of the elution test of harmful materials, a small amount was detected in the item of hexavalent chromium but satisfied the inclusion criteria, and in the remaining items, heavy metals were not eluted.

• Economic and Environmental Geology
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• v.46 no.6
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• pp.521-533
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• 2013

This study was initiated to evaluate the applicability of Si slag as an adsorbent via investigation of the main properties of Si slag as an adsorbent aw well as characterization of adsorption features between aqueous arsenic and Si slag. The specific surface area of Si slag was measured to be 6.71 $m^2/g$ which seems to be slightly higher than those of other slags, but relatively lower than those of iron (oxyhydr)oxides extensively used for arsenic controlling processes. The point of zero salt effect (PZSE) of Si slag determined by potentiometric titration appeared to be comparatively high (7.3), indicating the Si slag may be favorably used for adsorption of arsenic which predominantly exists as an oxy-anions. The results of adsorption isotherm indicate that regardless of arsenic species, Langmuir-type isotherm is the most suitable to simulate the adsorption of arsenic onto Si slag. With regard to pH-dependence of arsenic adsorption, the adsorption maxima of arsenite was centered at pH 7, and the adsorption was remarkably decreased in the other pH conditions. In the case of arsenate, on the other hand, the adsorption was highest at the lowest pH (4.0) and then gradually decreased with the increase of pH. Based on the results of kinetic experiments, it is likely that the adsorption of arsenite approached equilibrium within 2 hr, but it took about 8 hr for arsenate adsorption to be equilibrated. In addition, the Pseudo second order was evaluated to be most consistent with the empirical data of arsenic adsorption onto Si slag in this study. Under identical conditions, the affinity of arsenate onto Si slag was estimated to be nearly 6 times higher than that of arsenite.