• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.1
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• pp.53-57
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• 2010

The influence of CaO addition on the crystallization temperature, crystal types, and microstructure of L-A-S ($Li_2O-Al_2O_3-SiO_2$) glass-ceramics system fabricated from a coal bottom ash, produced at thermal power plant, was studied. The glass transition and crystallization temperatures were shifted to the higher temperature position with increasing CaO content in a non-isothermal analysis using a DTA. The major crystalline phases of L-A-S glass-ceramics system produced were identified as ${\beta}$-spodumene ($LiAlSi_2O_6$) and eucryptite ($LiAlSiO_4$). The glass-ceramics showed a bulk and surface crystallization behavior at a time. With increasing CaO content, the ${\beta}$-spodumene peak in XRD increased and some CaO-related phases were formed. The surface crystal grown from the exterior to the center in glass-ceramics showed various shapes by amount of CaO added. Some cracks were generated at the glass-ceramics containing CaO above 9 wt% due to the mismatch of thermal expansion coefficients between a ${\beta}$-spodumene and CaO-related crystal phases.

• Resources Recycling
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• v.19 no.1
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• pp.33-39
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• 2010

The spheric sintered body with $6{\pm}2mm$ diameter was manufactured in a rotary kiln at $1125^{\circ}C$/15 min using green body formed by pelletizing the batch powder composing of coal bottom ash produced from power plant and dredged soil by 70:30, wt%. And the physical properties of sintered body (BD) were analyzed to confirm the possibility for applying to an absorbent to restore a contaminated soil. The sintered body had a giant pore above 100 ${\mu}m$ and a fine pore below 10 ${\mu}m$, and bulk density was 1.4. Also its specific surface area, porosity and void proportion were $12.0m^2/g$, 30.1% and 38.2% respectively. The crushed body (BD-C), produced by crushing a BD specimen into an irregular shape with a aspect ratio of about 2, was similar to BD specimen at bulk density and pore size distribution. But it had superior values of specific surface area, porosity and void proportion compared with BD specimen owing to a decreased apparent volume due to conversion of closed pore existed at interior of BD to open pore during a crushing process. The IEP of sintered body occurred at about pH=5, so the optimum pH condition of reacting aqueous solution could be known before bonding a microbe to the sintered body. Hence, the optimum void proportion and porosity of an absorbent can be obtained by appropriate mixing a BD with BD-C from the base data calculated in this study.

• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.1
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• pp.1-7
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• 2014

This paper aims to explain the safety assessment and remediation mechanism of Granulated Coal Ash (GCA) as a material for the remediation of coastal sediments and to evaluate the improvement of the sediment in Kaita Bay, where GCA was applied. The concentrations of heavy metal contained in GCA and the dissolved amounts of heavy metal from GCA satisfied the criteria for soil and water pollution in Japan. The mechanisms on the remediation of coastal sediments using GCA is summarized as follows; (1) removal of phosphate and hydrogen sulfide (2) neutralization of acidic sediment (3) oxidation of reductive sediment (4) increase of water permeability (5) increase of soil strength (6) material for a base of seagrass. From the results obtained from the field experiment carried out in Kaita Bay, it was clarified that GCA is a promizing material for remediation of coastal sediment. This remediation technology can contribute to promote waste reduction in society and to decrease cost of coastal sediment remediation by applying GCA in other polluted coastal areas.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.4
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• pp.492-499
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• 2021

In this study, the benthic environmental and microbial community structure were investigated by mixing granulated coal ash(GCA) and contaminated estuary sediments. Estuary sediments and GCA were mixed in a ratio of 8:2 and allowed to interact for 1 month, then sediment environmental factors were investigated. The pH of the experimental sediment was mixed increased to 11. The concentration of DIP(Dissolved inorganic phosphorus) in the experimental case decreased by 30 % compared to the control case, and this should be due to formation of calcium phosphate through the chemical reaction of DIP and calcium which diluted from GCA. The high abundance of Gammaproteobacteria seen in the experimental sediment compare to the control can af ect the DIP reduction. The DIN(Dissolved inorganic nitrogen) concentration increased over two times in the experimental case than the control, and this should be due to the high pH condition and release of NH₄⁺-N from the GCA. Microorganisms related to nitrogen circulation were not identified in both the control and experimental cases. It was confirmed that the GCA were effective in reducing the DIP concentration in contaminated estuary sediment, and that benthic microbial communities were shown to influenced the phosphorus circulation.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.18 no.6
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• pp.271-276
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• 2008

The civil engineering properties for the coal fly ash produced from a power plant mixed with sintered powders made from the fly ash-clay slip system were measured and its applicability for the foundation soils was investigated. The F-slip whose dispersion state is 'not good' and C-slip which is re-flocculated by adding a flocculant to a well-dispersed slip were fabricated and then sintered. The sintered body made from C-slip had more uniform microstructure than that of F-slip, therefore, the bulk density and compressive strength were improved. The civil engineering properties such as compression index, compressive strength, permeability coefficient of fly ash were improved by mixing $0.84{\sim}2\;mm$ powders obtained by crushing a sintered body made from C-slip. Therefore, the applicability of mixed powders composing of fly ash and sintered body made from C-slip was confirmed to foundation soils due to its improved civil engineering properties.

• Resources Recycling
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• v.28 no.6
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• pp.64-72
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• 2019

Fly ash has different chemical composition depending on the type and quality of flaming coal. Fly ash is classified according to carbon content and particle size. Waste glass powder is manufactured by crushing glass. Exterior Insulation Finish System (EIFS) is generally applied by using poly-styrene foam which is economical and has excellent thermal insulation performance. However, poly-styrene foam has excellent insulation performance, but it is vulnerable to fire, which is becoming a serious problem. In this study, using a fly ash and waste glass powder to produce a finishing mortar at high temperatures. Also, High temperature strength and flame retardant properties were tested according to the cover thickness. From the test result, finishing mortar prepared using fly ash and waste glass powder is due to the improved heat resistance by alkali-activated bonding. However, since the strength decreases at high temperatures, it is necessary to select an appropriate mixing proportion.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.1
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• pp.182-188
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• 2008

The compounds of recycled polyethylene(PE) and fly-ashes were prepared. Polymers used were sorted PE from mixed plastics of household waste and Low Density Polyethylene(LDPE) and Linear Low Density Polyethylene(LLDPE) recycled from the scrap of packaging film plants. Fly-ashes were from the power plant and from the household waste incinerator. The tensile strength of recycled LDPE and LLDPE compounds decreased and the flexural modulus increased with greater amount of the power plant fly-ash. Anthracite fly-ash gave rise to slightly higher tensile and flexural strength of the LLDPE mixtures than bituminous coal fly-ash presumably due to higher content of unburned carbon. The incinerator fly-ash introduced to household waste PE enhanced both tensile strength and flexural modulus of the compounds. When LDPE and household waste PE were used together, the synergistic effect of incinerator fly-ash to household waste PE was offset by reduced crystallization of LDPE due to the filler particle. The compounds of household waste PE and incinerator fly-ash might be applied to structural materials for such as sewage pipe, which reduces the waste treatment cost and conserve the environment and resources.

• Journal of the Korean Ceramic Society
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• v.39 no.6
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• pp.558-565
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• 2002

Coal fly ash, produced from a power plant in Korea was used for the production of glass-ceramics and the physical properties of glass-ceramics were evaluated. CaO and TiO$_2$ were added into the fly ash during the melting process to reduce the viscosity of molten glass and to induce internal crystallization of glass, respectively. Glass-ceramic was produced through a single stage heat treatment (at 950∼1050$\^{C}$ for 37∼240 min) after preparing glass (iota fly ash powder. As a result, a new tiny rod type crystals (a=7.4480, b=10.7381, c=4.3940 A, $\alpha$=94.9, $\beta$=98.6, γ=108.5°) was found in the glass-ceramics, which showed attractive mechanical properties, high hardness (7.1∼7.6 GPa) and wear resistance (by erosion test). Thus a glass-ceramic produced from thermal power plant fly ash and cell as a source for CaO exhibits a suitable treatment for the recycling and exploitation of waste materials and would be acceptable for a new application far building materials.

• Korean Journal of Environmental Agriculture
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• v.26 no.2
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• pp.141-148
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• 2007

Fly ash, a by-product of the coal-burning industry, and a potential source of ferro-alumino-silicate minerals, which contains high amount of ferric oxide and manganese oxide (electron acceptors), was selected as soil amendment for reducing methane $(CH_4)$ emission during rice cultivation. The fly ash was applied into potted soils at the rate of 0, 2, 10, and 20 Mg $ha^{-1}$ before rice transplanting. $CH_4$ flux from the potted soil with rice plants was measured along with soil Eh and floodwater pH during the cropping season. $CH_4$ emission rates measured by closed chamber method decreased gradually with the increasing levels of fly ash applied but rice yield significantly increased up to 10 Mg $ha^{-1}$ application level of the amendment. At this amendment level, total seasonal $CH_4$ emission was decreased by 20% along with 17% rice grain yield increment over the control. The decrease in total $CH_4$ emission may be attributed due to suppression of $CH_4$ production by the high content of active and free iron, and manganese oxides, which acted as oxidizing agents as well as electron acceptors. In conclusion fly ash could be considered as a feasible soil amendment for reducing total seasonal $CH_4$ emissions as well as maintaining higher grain yield potential under optimum soil nutrients balance condition.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.3
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• pp.75-81
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• 2009

The industrial by-products market has increased at a geometric rate worldwide with the rapid economic growth. Among the wide variety of industrial by-products, fly ash which is generated by the combustion of coal is one of the more troublesome industrial wastes because they entail substantial disposal cost and also cause a shortage of disposal sites. In Korea alone, fly ash generation is expected to increase to 5.8 million tons by 2009, and to 6 million tons by 2010. Given the accelerated industrial development in developing countries, the amount of fly ash generation is predicted to reach enormous levels throughout the world. An increasing number of studies have currently focused on the feasibility of recycling industrial wastes i.e., fly ash in terms of environmental advantages. In this study, the optimized mix proportion of high performance shotcrete using fly ash was determined for the purpose of promoting recycling and reuse of resources.