• 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.

• Computers and Concrete
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• v.21 no.5
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• pp.531-538
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• 2018

The slag through sieve #4 replaced the natural fine aggregate in different proportions (0-50%) to make ready-mixed soil and slag (RMSAS). The fresh properties studied, and the concrete specimens were produced to test the hardened properties at different ages. Results showed that the workability of RMSAS decreases when the replacement increases. The unit weight increases with the replacement. The setting time extends when the replacement decreases and shortens when the replacement increases. The compressive strength, ultrasonic pulse velocity and hammer rebound value increase with the replacement. However, the high-replacement results decrease because of the expansion factor at late age. Resistivity is close and less than $20k{\Omega}-cm$. After the industrial of steelmaking by-products are processed properly, they can be used in civil engineering, not only as a substitute for natural resources and to reduce costs, but also to provide environmental protection.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.05a
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• pp.257-258
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• 2012

With regard to the carbon reduction that has become an international problem, we have examined the effects of compressive strength of the ground granulated blast-furnace slag mortar with the curing temperature. Also, we evaluated the mechanical properties of steel slag powder produced during the steelmaking process in order to examine the possibility as admixture.

• Resources Recycling
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• v.8 no.1
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• pp.11-17
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• 1999

This study was carried out to investigate the efficiency of stcclmaldng slag and sludge in removing metals existing in wastewater or leachate. Laboratory experiments were performed as a function of initial concentration of metals. pH a and temperature of the background solution and the presence of che1ating agent, EDTA. The test conditions were temperatures r ranging from $25^{\circ}C$ to $50^{\circ}C$; initial concentrations varying from 5mg/L to 50 mg/L; pH between 3 and 11; and Cu. Cd‘ and Pb a as adsorbates. The results of tests showed that overall rates of metals removal were 20~30% at pH 3 and greater than 90% at p pH 7 and 11. Metals were removed from the solution predominantly via adsorption in acidic conditions, and the combined e effects of adsorption and precipitation in neutral and alkaline conditions. In view of the test results and other engineering c characteristics of steelmaking slag and sludg$\xi$, these industrial by-products from steel industry have a high potential to be used l in wastewater treatment and are particularly beneficial when used as landfill liner additives due to thelJ ability to remove heavy m metals from leachate.

• Clean Technology
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• v.30 no.2
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• pp.113-122
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• 2024

In order to better understand carbon dioxide recycling, the carbon dioxide capture characteristics of six different alkaline industrial by-products, including incineration ash, desulfurized gypsum, low-grade quicklime, and steelmaking slag were investigated using a laboratory-scale direct aqueous carbonation reactor. In addition to the dissolution characteristics of each sample, the main reaction structure was confirmed through thermogravimetric analysis before and after the reaction, and the reactive CaO content was also defined through thermogravimetric analysis. The carbon dioxide capture capacity and efficiency of quicklime were determined to be 473 g/kg and 86.9%, respectively, and desulfurized gypsum and incineration ash were also evaluated to be relatively high at 51.1 to 131.7 g/kg and 51.2 to 87.7%, respectively. On the other hand, the capture efficiency of steelmaking slag was found to be less than 10% due to the influence of the production and post-cooling conditions. Therefore, in order to apply the carbonation process to steelmaking slag, it is necessary to optimize the slag production conditions. Through this study, it was confirmed that the carbon dioxide capture characteristics of incineration ash, quicklime, and desulfurized gypsum are at levels suitable for carbonation processes. Furthermore, this study was able to secure basic data for resource development technology that utilize carbon dioxide conversion to produce calcium carbonate for construction materials.

• International Journal of Advanced Culture Technology
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• v.10 no.1
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• pp.284-293
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• 2022

After extracting the calcium component from the KR slag and the converter slag using ammonium chloride solution, the extract was reacted with carbon dioxide to synthesize precipitated calcium carbonate (PCC). In order to understand the effect of ultrasonic waves on calcium extraction from slags and calcium carbonate synthesis, the efficiency of calcium carbonate synthesis according to the with or without of ultrasonic waves was analyzed. The synthetic efficiency of PCC was investigated according to various experimental conditions, and the synthesized calcium carbonate was analyzed using XRD and SEM. In both slags, the amount of PCC decreased as the reaction temperature increased. The pH at the end of the experiment capable of synthesizing the maximum PCC in the carbonation reaction was 7 (irradiated with ultrasound) and 8 (irradiated without ultrasound), respectively. Because the pH of the extraction filtrate is different when irradiated with or without ultrasound, the pH was adjusted to 9 by injecting an additive (10 M NaOH) before the carbonation experiment, and then the experiment was performed. When calcium was extracted from KR slag, the crystal phase appeared as calcite regardless of the pH at the end of the experiment. However, when calcium was extracted from the converter slag and the pH was set to 7 at the end of the experiment, the crystal phase of PCC appeared as a mixture of calcite and vaterite.

• Resources Recycling
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• v.30 no.6
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• pp.53-60
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• 2021

In EAF steelmaking industries, MgO content in slag increases due to the addition of dolomite flux to protect refractory lines of furnaces and improve the desulfurization capability of slag. In addition, coal powder is injected in the molten steel bath to increase the energy efficiency of the process. In this regard, the utilization of waste MgO-C refractory material as a flux was examined because it has high amounts of MgO (>70%) and graphite carbon (>10%). A series of experiments were carried out using industrial EAF slag with added light burnt dolomite and waste MgO refractory material from a Korean steel company. The results for the addition of the two fluxes were similar in terms of slag basicity; therefore, it is expected that waste MgO-C refractory material can successfully replace dolomite flux. In addition, when the waste MgO-C refractory material was added as flux, slag foaming phenomenon was demonstrated because of the reaction between the graphite from the refractory material and iron oxides in the slag.

• 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%.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.3
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• pp.153-157
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• 2010

We studied the adsorption efficiency of steelmaking slag in removing volatile organic compounds (VOCs) for increasing the recycling rate of steel-making slag. Ceramic filter was prepared by mixing the steel-making slag and the diatomite which is used as adsorbents due to the advantage of the high specific surface area and regular mesopores. The adsorption efficiency for VOCs removal was about 80%, 96% and 85% in acetaldehyde, formaldehyde and ammonia, respectively. The adsorption efficiency over 80% for all The gases showed the practical possibility as the adsorption filter.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10b
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• pp.1316-1321
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• 1990

Molten steel level information of ladle is very important for process control in steelmaking process. At secondary refining process, measuring lance and snokel have to keep constant thier depth from molten steel surfaces. But, there is much slag on the molten steel surface. Besides, not only the thickness of slag is varied with refining condition, but also molten steel level is largely affected by firebrick errosion. Then, optical measuring method and/or by human eyes cannot detect true molten steel surface, but slag surface. This slag thickness is 300mm at maximum, then huge diameter eddy current sensor will be needed if that type sensor is applied. In addition to, cooling system is necessary because the molten steel and slag temperature is high. This is not practically. To solve this problem, immersion type levelmeter is developed. This sensor is made up from primary and secondary cylindrical coils. High frequency current is applied to primary coil. Electro-motive force from secondary coil is measured, which is varied with molten steel level. This complete set is installed within stainless steel long capsule and attached to top of lance. This sensor is immersed into molten steel bath of ladle or tundish with protection of expendable paper sleeve.