• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.4
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• pp.18-25
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• 2020

The purpose of this study is to investigate the mechanical and carbon-capture properties of foam concrete containing stainless steel argon oxygen decarbonization(AOD) slag. AOD slag was used as a binder, and foam concrete having a foaming ratio of 69 ± 0.5 % and a slurry density of 573.2 to 578.6 kg / ㎥ was produced. In order to examine the effect of carbonation, blended specimen was cured by two types : normal curing and CO₂ curing. As a result of the experiment, the specimens incorporating AOD slag showed higher compressive strength than Plain after CO₂ curing. According to the analysis of the image of foam concrete, it was confirmed that the ST30 has a lower total pore volume and average pore size than plain, resulting in high compressive strength. The SEM analysis confirmed the formation of calcite by carbonation of AOD slag. Through the thermogravimetric analysis, the increase of CO₂ uptake was confirmed by the incorporation of AOD slag. Foam concrete has a higher porosity than normal concrete, so it is expected that carbon-capture performance can be improved by using a AOD slag.

• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.4
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• pp.65-72
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• 2022

For sustainable development in the construction industry, blast furnace slag has been used as a substitute for cement in concrete. In contrast, ferronickel slag, which is the by-product generated during smelting to ferronickel used in the manufacturing of stainless steel and nickel alloys, has a limitation to use as a binder and an aggregate due to its expansive characteristics. Recently, stabilization technology of ferronickel slag has been improved and studies have been carried out to utilize ferronicke slag as fine aggregate in concrete. Therefore, in this study, basic mechanical properties of concrete used in ferronickel slag aggregate was evaluated. The compressive strength (24, 30, 40 MPa) and replacement rate of ferronickel slag aggregate (0, 10, 25, 50%) were considered as experimental variables. As a result of test, concrete replaced fine aggregate with 25% ferronickel slag aggregate showed superior performance in the compressive strength and flexural strength.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.404-408
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• 2001

This paper focuses on the pilot-scale investigation of direct recycling of electric arc furnace (EAF) stainless steelmaking dust. The direct recycling of EAF dust is to make pellets with the mixture of the dust and the reducing agent carbon, then introduce the pellets to the EAF. The valuable metals in the dust are reduced and get into the steel as the alloying elements. Experiments simulating direct recycling in an EAF were performed using an induction furnace. But it seems difficult to reduce all metal oxides in the dust so that some metal reducing agents added in the late stage of reduction process. The valuable metals in the dust were reduced partly by carbon and partly by metal reducing agent for the economical concern. The recovery of iron, chromium and nickel from the flue dust and the amount of metal oxides in the slag were measured. The results showed that the direct recycling of EAF stainless steelmaking dust is practicable. It wes also found that direct recycling of flue EAF stainless steelmaking dusts does not affect the chemistry and quality of stainless steel produced in the EAF. It is benefit not only for the environmental protection but also for the recovery of valuable metal resources in this way.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.206-207
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• 2017

We investigated the fluidity and compressive strength properties of mortar by Grading Variation of Ferro-Nickel Slag Sand in order to improve the utilization of ferro-nickel which is the by-product produced by making stainless steel, in the construction industry.

• Journal of Environmental Health Sciences
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• v.25 no.3
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• pp.108-112
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• 1999

A study was conducted for the effects of input energy on fume formation ratios based on electrode(FFR$_{electrode}(g/kg_{electrode})),\;deposited\;metal(FFR_{weld}(g/kg_{weld}))\;and\;slag(FFR_{slag}(g/kg_{slag}))\;at\;CO_2$ flux cored arc welding on stainless steel. Experiments were run in well designed welding fume box. Six types of flux cored wires were used and three levels of current and voltages were given. The measured values of $FFR_{electrode},\;FFR_{weld},\;FFR_{slag}\;are\;7.90{\pm}1.47\;g/kg_{electrode},\;9.18{\pm}1.65\;g/kg_{\electrode},\;71.8{\pm}24.2\;g/kg_{slag}$ respectively. Fume formation ratios are not increased dramatically by input energy because of simultaneous increasing of melted electrodes, deposited metal and slag. The results indicate that the test of fume formation ratios in the research on production of low fume welding wire can be run at the fixed condition of input energy rather than various condition.

• Resources Recycling
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• v.20 no.1
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• pp.3-13
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• 2011

Taiwan's annual steel production reached 21.29 million tons. EAF accounted for about half of this total, or 11.2 million tons in 2008. The other 10.09 million tons came from blast furnace and converter process methods. The annual EAF carbon steel production is about 9.76 million tons, and the quantity of dust generated from the EAF process is 160 thousand tons, or about 16kg of dust per ton of steel was produced. In 2009, there is Walez process for carbon steel EAF dust recycling, and the capacity is about 70,000 tons per year; and there is RHF/SAF process for stainless steel EAF dust, the capacity is 60,000 tons per year which is enough to treat stainless steel EAF dust in Taiwan. There are many new treatment facilities processes will be that introduced to recycle the EAF dust in the near future, these processes will perform smoothly and successfully in Taiwan. The estimation of recycled crude ZnO is about 90,000 tons each year. The recycling and upgrading crude zinc oxide will be the next important issue in Taiwn zinc and steel industry.

• Journal of Welding and Joining
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• v.18 no.2
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• pp.49-56
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• 2000

Recently developed Austenite stainless steel, 309L was used to overlay on 3Cr-1Mo-V-Ti-B steels, using Electroslag welding process, which wide electrodes were adopted. Transition region in welding interlayer relating to disbonding crack was investigated. Also, the effect of welding condition on the width of transition region and coarsening grains of the austenite were studied. 1) With increasing welding speed the width of martensite at transient region was increased, but the amount of delta ferrite in weld metal was reduced, being fine grained. 2) The form of martensite at the transition region was occurred by reversible transformation during cooling since the interdiffusion of Cr and Ni from weld metal and Fe and C from base metals at the transition region, causes to lowering the concentration of Cr and Ni at the transition region, leading to increasing Ms point. 3) With increasing welding speed, the grain of austenite formed at the welding interface was finer. With increasing welding current under the same welding speed, the grain size of the austenite was finer. At high current, original grain size of the austenite is coarse, but the austenite has fine grains because the austenite was transformed to martensite during cooling. 4) In the case of high welding speed, the width of martensite at the welding interface was increased, but the grain size of austenite at the welding interface was finer. This indicates that the inhibition of disbonding crack may be achieved through dispersening fine carbides in the gain boundary.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.107-109
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• 2012

In Korean coal power plants, rising coal prices have recently led to the rapid utilization of low lank coals such as sub-bituminous coal with low calorific values and low ash fusion temperatures. Using these coals beyond the design range has resulted in important issues including slagging and fouling, which cause negative effects in boiler performances and unstable operations. The purpose of this study is to observe slagging and fouling characteristics resulted from burning various ranks of pulverized coals. We have tested 3 different coals: FLAME(bituminous), KCH(sub-bituminous) and MOOLARBEN(bituminous)coals in the pilot system $50kW_{th}$ scale. A stainless steel tube with preheated air inside was installed in the downstream in order to simulate water wall. Collected ash on the probe and the slag inside the furnace near burner were analyzed by SEM (scanning electron microscopy) to verify the formation degree, surface features and color changes of the pasty ash particles. Induced coupled plasma and energy dispersive X-ray spectroscopy were also performed to figure out the chemical characteristics of collected samples. As a result, KCH was observed that more slag was developed inside the walls of the furnace and on the probe than the other two kinds of coals, as shown in the calculate slagging and fouling indices as well.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.3
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• pp.133-142
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• 2014

Recently, more focus is shift to imbalances in aggregate market supply and demand and an exhaustion of natural resources. In this situation, Electric arc furnace oxidizing slag (EAF Slag) has high application possibility as aggregate for concrete due to similar property with general aggregate. In this study, We've got the plan to assure the chemical stability of EAF Slag, and then experimentally tested the mechanical performance and durability for the fine aggregate used EAF Slag. On this test result, we suggest the application plan. At the result of this study, it shows that EAF slag would reduce the surface defect such as pop-out due to natural aging for the fixed hour and adjustment the grain size of EAF Slag. And mechanical performance and durability according to the replacement rate of concrete service, were revealed more than equal or equal compare to general aggregate. Hereafter, quality control must precede not to impede the beauty of concrete surface as assure the safety for aging and processing. And, to establish the environmental resource recycling system for by-products of steel, it should be made development of various application and guideline of quality control for the EAF slag aggregate. Moreover, it must be constantly studied all kind of engineering performance and durability for related to this study.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.4
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• pp.1309-1319
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• 1996

The research for the classification of the natural defects in welding zone is performd using the neuro-pattern recognition technology. The signal pattern recognition package including the user's defined function is developed to perform the digital signal processing, feature extraction, feature selection and classifier selection, The neural network classifier and the statistical classifiers such as the linear discriminant function classifier and the empirical Bayesian calssifier are compared and discussed. The neuro-pattern recognition technique is applied to the classificaiton of such natural defects as root crack, incomplete penetration, lack of fusion, slag inclusion, porosity, etc. If appropriately learned, the neural network classifier is concluded to be better than the statistical classifiers in the classification of the natural welding defects.