In this study used Computational Fluid Dynamic analysis to examine NOx reduction in hydrogen combustion, analyzing six conditions with varying air/fuel ratios, temperatures, and concentrations. Results were compared between two combustor shapes and previous experimental data. Findings showed increased air/fuel ratios decreased flame temperature and increased post-combustion O2. NOx emissions peaked at high temperatures and low O2. Numerical results aligned with previous experimental trends, validating the approach. Combustor shape differences, reflecting variations in fuel and air pipes, significantly affected flow rates and combustion positions. This reduced NOx emissions up to a certain air/fuel ratio, but excessive increases diminished this effect. The study highlights the complex relationship between combustor design, operating conditions, and NOx emissions. Further research is needed to optimize NOx reduction by considering pipe numbers and combustion locations. Future studies should explore various combustor geometries, fine-tune air/fuel ratios, and investigate additional parameters influencing NOx formation and reduction in hydrogen combustion systems.

This study involved the heterogenization of a binder pitch (BP) using a small amount of nanocarbon to improve physical properties of the resulting graphite electrode (GE). Heterogenization was carried out by adding 0.5–2.0 wt.% platelet carbon nanofiber (PCNF) or carbon black (CB) to a commercial BP. To evaluate the physical properties of the BPs, we designed a new model graphite electrode (MGE) using needle coke as a filler. The heterogenized binder pitch (HBP) with PCNF or CB clearly increased the coking value by 5–13 wt.% compared to that of the as-received BP. Especially, the model graphite electrodes prepared with HBPs containing 1.0 wt.% PCNF or CB showed significantly improved physical properties compared to the control MGE from the as-received BP. Although the model graphite electrodes prepared with HBPs showed similar properties, they had smaller pore sizes than the control. This indicates that heterogenization of the BP can effectively decrease the pore size in the MGE matrix. Correlating the average pore sizes with the physical properties of the model graphite electrodes showed that, for the same porosity, matrices formed by the HBP with a smaller average pore size can effectively improve the apparent density, tensile strength, and oxidation resistance of the model graphite electrodes.

In this study, numerical modeling on the gas flow and off-gases in the low temperature carbonization furnace for carbon fiber was analyzed. The furnace was designed for testing carbonization process of carbon fibers made from various precursors. Nitrogen gas was used as a working gas and it was treated as an incompressible ideal gas. Three-dimensional computational fluid dynamics for steady state turbulent flow was used to analyze flow pattern and temperature field in the furnace. The off-gas mass fraction and cumulative emission gas of species were incorporated into the CFD analyses by using the user defined function(UDF). As a results, during the carbonization process, the emission of CO2 was the dominant among the off-gases, and tow moving made the flow in the furnace be uniform.

In this study, gas flow pattern and temperature distribution in a laboratory scale low temperature furnace for carbonization were numerically analyzed. The furnace was designed for testing carbonization process of carbon fibers made from polyimide(PI) precursor. Nitrogen gas was used as a working gas and it was treated as an ideal gas. Three-dimensional computational fluid dynamics analysis for steady state turbulent flow was used to analyze flow pattern and temperature field in the furnace. The results showed that more uniform velocity profile and axisymmetric temperature distribution could be obtained by varying mass flow rate at the inlets.

PURPOSES : This paper presents the experimental results of tests conducted on concrete produced with air-cooled (AS) and water-cooled (WS) ground blast-furnace slag exposed to multi-deterioration environments of carbonation and scaling. METHODS : Carbonated and uncarbonated concrete specimens were regularly monitored according to the ASTM C 672 standard to evaluate the durability of concrete exposed to both scaling and combined carbonation and scaling conditions. Additionally, mechanical properties, such as compressive strength, flexural strength, and surface electric resistivity, were analyzed. RESULTS : It was found that concrete specimens produced with AS and WS had a beneficial effect on the mechanical properties because of the latent hydraulic properties of the AS and WS mineral admixtures. Moreover, carbonated concrete showed good scaling resistance in comparison to uncarbonated concrete, particularly for concrete produced with AS and WS. CONCLUSIONS : The improved scaling resistance of carbonated concrete showed that AS is a suitable option for binders used in cement concrete pavements subjected to combined carbonation and scaling.

Geopolymers have many advantages over Portland cement, including energy efficiency, reduced greenhouse gas emissions, high strength at early age and improved thermal resistance. Alkali activated geopolymers made from waste materials such as fly ash or blast furnace slag are particularly advantageous because of their environmental sustainability and low cost. However, their durability and functionality remain subjects for further study. Geopolymer materials can be used in various applications such as fire and heat resistant fiber composites, sealants, concretes, ceramics, etc., depending on the chemical composition of the source materials and the activators. In this study, we investigated the thermal properties and microstructure of fly ash and blast furnace slag based geopolymers in order to develop eco-friendly construction materials with excellent energy efficiency, sound insulation properties and good heat resistance. With different curing times, specimens of various compositions were investigated in terms of compressive strength, X-ray diffraction, thermal property and microstructure. In addition, we investigated changes in X-ray diffraction and microstructure for geopolymers exposed to 1,000 oC heat.

This study was performed in order to obtain the effect of the compressive strength of the cured product with manufacturing conditions (amounts of fine aggregate and different types of alkali activator). Material which is the basis of the cured product was used for the blast furnace slag, which has a latent hydraulic activity. Consequently, when using sodium hydroxide as the alkali activator, it is possible to obtain a higher compressive strength than using the calcium hydroxide. And also, it can be added a 10% of fine aggregate with blast furnace slag to improve the compressive strength.

PURPOSES: This study investigates the mechanical performance of carbon-capturing concrete that mainly contains blast furnace slag. METHODS: The mixture variables were considered; these included Portland cement content, which was varied from 10% to 40% of the blast furnace slag by weight. The specimens were exposed to different conditions such as high N2 and O2 concentrations, laboratory conditions and high CO2 conditions. Mechanical performances, including compressive and flexural strengths and carbon-capturing depth, were evaluated. RESULTS : The slump, air content and unit weight were not affected significantly by the variation in cement content. The strength development when the specimens were exposed to high purity air was slightly greater than that when exposed to high CO2. As the cement content increased the compressive and flexural strength increased but not considerably. The carbon-capturing capacity decreased as the cement content increased. The specimens exposed in the field for 70 days had flexural strength greater than 3 MPa. CONCLUSIONS : The results indicate that cement content is not an important parameter in the development of compressive and flexural strengths. However, the carbon-capturing depth was higher for less cement content. Even after field exposure for 70 days, neither any significant damage on the surface nor any decrease in strength was observed.

고로슬래그는 유동성 장기강도 및 내구성이 좋고 수화열을 낮아 경화체를 제조함에 따른 적용성이 우수하지만, 몇 가지 문제점을 갖는다. 시공시간이 증가하고 회전속도가 늦고 초기강도가 낮다. 본 연구에서는 알칼리활성화를 이용한 경화체 제조에 있어 필요한 알칼리 수용액을 해수담수화 과정에서 발생하는 농축수의 전기분해를 통하여 공급하였으며. 알칼리 수용액을 이용하여 고로슬래그와 경화체를 제작하였다. 결과는 다음과 같이 요약할 수 있다 : 모르타르의 압축강도는 NaOH 2%이하일 때는 감소하고, 6% 이하까지는 증가한다. 그리고 NaOCl의 함량이 증가할수록 압축강도도 증가한다. 그러나 NaCl이 모르타르에 존재하면 초기강도보다 재령 28일차 강도는 감소하게 된다.

PURPOSES: In this study, alkali-activated blast-furnace slag (AABFS) was investigated to determine its capacity to absorb carbon dioxide and to demonstrate the feasibility of its use as an alternative to ordinary Portland cement (OPC). In addition, this study was performed to evaluate the influence of the alkali-activator concentration on the absorption capacity and physicochemical characteristics. METHODS: To determine the characteristics of the AABFS as a function of the activator concentration, blast-furnace slag was activated by using calcium hydroxide at mass ratios ranging from 6 to 24%. The AABFS pastes were used to evaluate the carbon dioxide absorption capacity and rate, while the OPC paste was tested under the same conditions for comparison. The changes in the surface morphology and chemical composition before and after the carbon dioxide absorption were analyzed by using SEM and XRF. RESULTS: At an activator concentration of 24%, the AABFS absorbed approximately 42g of carbon dioxide per mass of paste. Meanwhile, the amount of carbon dioxide absorbed onto the OPC was minimal at the same activator concentration, indicating that the AABFS actively absorbed carbon dioxide as a result of the carbonation reaction on its surface. However, the carbon dioxide absorption capacity and rate decreased as the activator concentration increased, because a high concentration of the activator promoted a hydration reaction and formed a dense internal structure, which was confirmed by SEM analysis. The results of the XRF analyses showed that the CaO ratio increased after the carbon dioxide absorption. CONCLUSIONS : The experimental results confirmed that the AABFS was capable of absorbing large amounts of carbon dioxide, suggesting that it can be used as a dry absorbent for carbon capture and sequestration and as a feasible alternative to OPC. In the formation of AABFS, the activator concentration affected the hydration reaction and changed the surface and internal structure, resulting in changes to the carbon dioxide absorption capacity and rate. Accordingly, the activator ratio should be carefully selected to enhance not only the carbon capture capacity but also the physicochemical characteristics of the geopolymer.

The properties of dust collected from electric arc furnace of ferro manganese production units was investigated, and also the metallic manganese was recovered from the dust by aluminothermy process. The ferromanganese dust collected from electric arc furnace contained about 15% of manganese oxide (Mn3O4) and 9% of carbon as the contaminant, and have a 5um of 50% median diameter and irregular particle shape. The carbon contaminant in the dust could be reduced until about 0.1~0.5% level by roasting in the air at a temperature of 600~900C for 60minutes. The recovery of manganese could not be carried out using only ferromanganese dust from electric arc furnace by aluminothermy process, but the ferromanganese which contained manganese of about 92% and iron of about 5% could be obtained from the mixture of ferromanganese dusts from electric arc furnace and converter. The best mixing condition of dust fixed at electric arc furnace dust / converter dust ratio of 1:9 and 2:8, and the mixing rato of 3:7 or more could not separated the metal and slag from the reactant after aluminothermy reaction.

PURPOSES: This paper, presents the results of a laboratory study aimed to verify the suitability of a particular type of Electric Arc Furnace (EAF) steel slag to be recycled in the lithic skeleton of both dense graded and porous asphalt mixtures for flexible pavements. METHODS : Cyclic creep and stiffness modulus tests were performed to evaluate the mechanical performance of three different asphalt mixtures (dense graded, porous asphalt, and stone mastic) prepared with two types of EAF steel slag. For comparison purposes, the same three mixtures were also designed with conventional aggregates (basalt and limestone). RESULTS : All the asphalt mixtures prepared with EAF steel slag satisfied the current requirements of the European standards, which support EAF steel slag as a suitable material for flexible pavement construction. CONCLUSIONS : Based on the experimental work, the use of waste material obtained from steel production (e.g. EAF steel slag) as an alternative in the lithic skeleton of asphalt mixtures can be a satisfactory and reasonable choice that fulfills the “Zero Waste”objective that many iron and steel industries have pursued in the past decades.

In this study, modified catalytic chemical vapor deposition (CCVD) method was applied to control the CNTs (carbon nanotubes) growth. Since titanium (Ti) substrate and iron (Fe) catalysts react one another and form a new phase (Fe2TiO5) above 700℃, the decrease of CNT yield above 800℃ where methane gas decomposes is inevitable under common CCVD method. Therefore, we synthesized CNTs on the Ti substrate by dividing the tube furnace into two sections (left and right) and heating them to different temperatures each. The reactant gas flew through from the end of the right tube furnace while the Ti substrate was placed in the center of the left tube furnace. When the CNT growth temperature was set 700/950℃ (left/right), CNTs with high yield were observed. Also, by examining the micro-structure of CNTs of 700/950℃, it was confirmed that CNTs show the bamboo-like structure.

The potential of marginal materials as components of road infrastructures has been studied for many years. The list of materials includes non-traditional natural materials (rocks and soils), industrial by-products (from metallurgical industry, thermal electric power stations, and chemical industry) and wastes (mining and quarrying, municipal, industrial and demolition wastes). Among these materials, Electric Arc Furnace Steel Slags (EAFSS) presents physical-mechanical characteristics and full chemical compatibility with the hydrocarbon binders used in road construction and, therefore, have high potential for being re-used. This paper presents the results of a laboratory study conducted to verify the suitability of a particular type of Electric Arc Furnace Steel Slag (EAFSS) to be recycled in the aggregate skeleton of dense graded and porous asphalt mixtures for pavements application. One dense graded mixture for wearin gcourse(WCAC), one Stone Mastic Asphalt(SMA) and one Porous Asphalt(PA) were prepared and compacted for this purpose. The computed results of Marshall Stability, Flow and Indirect Tensile Strength (ITS) values are presented in Table 1.

Occupational fatal injury rate per 10,000 population of Korea is still higher among the OECD member countries. To prevent fatal injuries, the causes of accidents including human error should be analyzed and then appropriate countermeasures should be established. There was an severe converter furnace accident resulting in five people death by chocking in 2013. Although the accident type of the furnace accident was suffocation, many safety problems were included before reaching the death of suffocation. If the safety problems are reviewed throughly, the alternative measures based on the review would be very useful in preventing similar accidents. In this study, we investigated the converter furnace accident by using human error analysis and accident scenario analysis. As a result, it was found that the accident was caused by some human errors, inappropriate task sequence and lack of control in coordinating work by several subordinating companies. From the review of this case, the followings are suggested: First, systematic human error analysis should be included in the investigation of fatal injury accidents. Second, multi man-machine accident scenario analyis is useful in most of coordinating work. Third, the more provision of information on system state will lessen human errors. Fourth, the coordinating control in safety should be performed in the work conducting by several different companies.

PURPOSES : In this study blast furnace slag, an industrial byproduct, was used with an activating chemicals, Ca(OH)2 and Na2SiO3 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℃. CONCLUSIONS: Compared with previous studies of this experiment is to some extent the optimal combination is expected to be reliable.

PURPOSES : To investigate the fundamental characteristics of blast-furnace slag mortar that was hardened with activating chemicals to capture and sequester carbon dioxide. METHODS : Various mix proportions were considered to find an appropriate stregnth development in regards with various dosages of activating chemicals, calcium hydroxides and sodium silicates, and curing conditions, air-dried, wet and underwater conditions. Flow characteristics was investigated and setting time of the mortar was measured. At different ages of 3, 7 and 28days, strength development was investigated for all the mix variables. At each age, samples were analyzed with XRD. RESULTS : The measured flow values showed the mortar lost its flowability as the activating chemicals amount increased in the scale of mole concentration. The setting time of the mortar was relatively shorter than OPC mortar but the initial curing condition was important, such as temperature. The amount of activating chemicals was found not to be critical in the sense of setting time. The strength increased with the increased amount of chemicals. The XRD analysis results showed that portlandite peaks reduced and clacite increased as the age increased. This may mean the Ca(OH)2 keeps absorbing CO2 in the air during curing period. CONCLUSIONS : The carbon capturing and sequestering activated blast-furnace slag mortar showed successful strength gain to be used for road system materials and its carbon absorbing property was verified though XRD analysis.

Furnace slag powder used currently in Korea needs to add special functions in response to the increase of large-scale projects. In addition, it is advantageous in that it has a lower hydration heat emission rate than ordinary Portland cement and improves properies such as the inhibition of alkali aggregate reaction, watertightness, salt proofness, seawater resistance and chemical reslstance. However, furnace slag powder is not self-hardening, and requires activators such as alkali for hydration. Accordingly, if recycled fine aggregate, from which calcíum hydroxide is generated, and furnace slag, which requires alkali stimulation, are used together they play mutually complementary roles, so we expect to use the mixture as a resource-recycling construction material. Thus the present study purposed to examine the properties and characteristics of furnace slag powder and recycled aggregate, to manufacture recycled fine aggregate mortar using furnace slag and analyze its performance based on the results of an experiment, to provide materials on mortar using furnace slag as a cement additive and recycled fine aggregate as a substitute of aggregate, and ultimately to provide basic materials on the manufacturing of resource-recycled construction materials using binder and fine aggregate as recycled resources.

  Glass melting process is influenced by both control and observation factors, where control factors include quantity and mixing ratio of raw material, the amount of fuel and air in-take. Further observation factors include temperature and pressure at eac