• Economic and Environmental Geology
• /
• v.28 no.2
• /
• pp.147-154
• /
• 1995

Coal fly ashes collected from the Samcheonpo and the Seocheon Power Plants were analyzed for major and minor components and heavy metals such as As, Cd, Co, Cr, Cu, Ga, Hg, Mo, Ni, Pb, Sb, V and Zn in order to suggest basic data to apply coal fly ash as fertilizer or soil ameliorator. The specific gravity of the samples was less than 2.0, and amounts of organic matter range from 5.0% to 12.3%. The identified minerals by XRD were mainly quartz, mullite and pyrite in anthracite coal, and mainly quartz and mullite in bituminous coal. Generally, the contents of heavy metal elements analyzed were lower less than those of soil, though higher in some samples. Element couples of some elements( e.g., As-Mo, Zn ; Mo-As, Sb, V, Zn ; Sb-Zn ) show positive correlations with each other, but the high correlations of toxic elements such as As, Pb, Cd and Hg indicate to give attention to apply coal fly ash as fertilizer or soil ameliorator.

• Journal of Powder Materials
• /
• v.13 no.2 s.55
• /
• pp.102-107
• /
• 2006

Recycling industrial wastes such as fly ash from a coal burning heat power plant and shell from an oyster farming were investigated to prevent environment contamination as well as to enhance the value of recycling materials. In this study, the lightweight aggregates and the red bricks were fabricated from fly ashes with other inorganic materials and wastes. The starting materials of the lightweight aggregate were fly ash powder and water glass, and the compacts of these materials were heat treated at $1100^{\circ}C$. The fabricated lightweight aggregates had low bulk density, $0.9-1.2\;g/cm^3$, hence floated on the water and had the strength of 7.0-11.0 MPa and the modulus of 2900-3300 MPa which indicates it has enough strength as the aggregate. Another type of the light weight aggregate was prepared from fly ashes, shell powders and clays. The bulk density, porosity, and compressive strength of these aggregates were $1.19-1.34\;g/cm^3,\;18.3{\sim}56.1%$ and 5-12 MPa, respectively. The addition of a small amount of fly ash powder prevented hydration of the light weight aggregates. The red brick was also fabricated from the fly ash containing materials. It is suitable for the brick facing of a building as it has moderate strength and low water absorption rate.

• Journal of environmental and Sanitary engineering
• /
• v.17 no.3
• /
• pp.37-45
• /
• 2002

The Purpose of this study is to reduce environmental problems caused by landfill of bituminous coal fly ash emitted from the power plant and to reuse it. First of all, we experimented that Al and Si elements were extracted from fly ash and investigated that extracted Al and Si elements night use a coagulant. The extraction was carried out under various conditions ; concentration of the extraction solution, calcination temperature and calcination time. As the results, it was found that the optimum conditions of the extraction of Al and Si elements from fly ash were as follows, concentration of NaOH was 5N for both of them, calcination temperature was $700^{\circ}C$ and $600^{\circ}C$ and calcination time was 1hr and 1.5hr, respectively The extracted solution was used as a coagulant to treat the diluted metal-plating solutions which contained Pb and Cu, respectively. As the result of treatment on the diluted Pb-plating solution with 315NTU, the removal efficiency of turbidity was more than 90%, and the removal efficiency of Pb was about 80%. As for treatment of the non-turbid diluted Cu-plating solution, the removal efficiency of Cu was about 98%.

• Korean Chemical Engineering Research
• /
• v.51 no.4
• /
• pp.493-499
• /
• 2013

For the purpose of utilizing fly ash from gasification of low rank coal, we performed the series of experiments such as pyrolysis and char-$CO_2$ gasification on fly ash by using the thermogravimetric analyzer (TGA) at non-isothermal heating conditions (10, 20 and $30^{\circ}C/min$). Pyrolysis rate has been analyzed by Kissinger method as a first order, the reliability of the model was lower because of the low content of volatile matter contained in the fly ash. The experimental results for the fly ash char-$CO_2$ gasification were analyzed by the shrinking core model, homogeneous model and random pore model and then were compared with them for the coal char-$CO_2$ gasification. The fly ash char (LG coal) with low-carbon has been successfully simulated by the homogeneous model as an activation energy of 200.8 kJ/mol. In particular, the fly ash char of KPU coal with high-carbon has been successfully described by the random pore model with the activation energy of 198.3 kJ/mol and was similar to the behavior for the $CO_2$ gasification of the coal char. As a result, the activation energy for the $CO_2$ gasification of two fly ash chars don't show a large difference, but we can confirm that the models for their $CO_2$ gasification depend on the amount of fixed carbon.

• Economic and Environmental Geology
• /
• v.30 no.5
• /
• pp.443-450
• /
• 1997

The main purpose of this study is to investigate mineralogical and chemical changes during natural weathering, and assess the mobility of major and trace elements. Yongwol power plant utilize anthracite coal which is mainly composed of illite, kaolinite, pyrophyllite and quartz in mineralogy. Coal and coal-derived fly ash samples were sampled by the electrostatic precipitator in Yongwol coal-fired power plant in Korea. Short term weathered fly ash were also collected in ash disposal mound, and two profile soil samples were taken from an ash near the power plant. Amorphous materials are the main component of the fly ash, and mullite, quartz, magnetite and heamatite are present in all coal-derived fly ash. In chemistry, Si and Al are the most abundant elements of the total content. The ash samples were fractionated into upper $90{\mu}m$ and under $45{\mu}m$ size. Finer particles show higher concentrations in metal contents including Co, Cr, Cu, Ni, V, Zn and Pb. Concentration of Zn and Pb are nearly 4 times higher concentration in the finer particles. For the profile samples, the concentrations of $SiO_2$, $Na_2O$, MgO and $K_2O$ generally show increasing trends with depth, whereas those of $Fe_2O_3$ and $TiO_2$ appear to decrease with depth. Content of MnO does not show any specific depth trend. For the trace elements, Co, Cu, Ni and V show increasing concentrations with depth.

• Journal of the Korean Society of Combustion
• /
• v.4 no.1
• /
• pp.67-83
• /
• 1999

The objective of this study is development of low emission pulverized coal combustor for reducing pollutant emission generated from coal combustion. Low emission combustion technology for reducing NOx and fly ash was investigated by using 2 stage coaxial cyclone combustor. Staged combustion was employed for NOx reduction and high temperature slagging combustion was also studied for fly ash removal in the combustor. The result of this study shows that the low emission combustion system can reduce the amount of atmospheric pollutions with improved boiler efficiency and performance.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.7 no.1
• /
• pp.43-52
• /
• 1999

This study was carried out to investigate how much coal fly ash could be substituted for sawdust as a bulking agent for livestock waste composting. The mixtures of coal fly ash and sawdust in the weight ratio of 8 to 2, 7 to 3, 6 to 4, 5 to 5, 4 to 6, 3 to 7 and 2 to 8 were added to livestock waste as the bulking agent. The same amount of the bulking agents and livestock waste was mixed and composted during 21 days. Following effects were analyzed during composting experiment : the variation of temperature, pH and various compound contents. The results were summarized as follows: The more the sawdust was added, the higher the maximum temperature in slurry type livestock farm but faster it reached in scrapper type. Water content was maintained under good condition by adding the bulking agent mixed of the same amount of coal fly ash and sawdust. pH was in the range of 7~10 by adding the bulking agent mixed of the same amount of coal fly ash and sawdust. The more the sawdust was added, the higher organic matter content was measured. Nitrogen content with increasing the amount of sawdust added but it was higher did not showed any tendency Organic matter/Nitrogen ratio reduced during the composting period in scrapper type but it showed contrary tendency in slurry type with that of scrapper type.

• Journal of Environmental Science International
• /
• v.23 no.12
• /
• pp.1987-1998
• /
• 2014

Zeolite was synthesized from power station waste, coal fly ash, as an alternative low-cost adsorbent and investigated for the removal of Sr(II) and Cs(I) ions from single- and binary metal aqueous solutions. In order to investigate the adsorption characteristics, the effects of various operating parameters such as initial concentration of metal ions, contact time, and pH of the solutions were studied in a batch adsorption technique. The Langmuir model better fitted the adsorption isotherm data than the Freundlich model. The pseudo second-order model was found more applicable to describe the kinetics of system. The adsorption capacities of Sr(II) and Cs(I) ions obtained from the Langmuir model were 1.7848 mmol/g and 0.7640 mmol/g, respectively. Although the adsorption capacities of individual Sr(II) and Cs(I) ions was less in the binary-system, the sum of the total adsorption capacity (2.3572 mmol/g) of both ions in the binary-system was higher than the adsorption capacity of individual ion in the single-system. Comparing the homogeneous film diffusion model with the homogeneous particle diffusion model, the adsorption was mainly controlled by the particle diffusion process.

• Journal of Environmental Science International
• /
• v.31 no.10
• /
• pp.833-844
• /
• 2022

A zeolite material with a Si/Al molar ratio of 1.2 was synthesized by changing the NaOH/CFA ratio of coal fly ash (CFA) via a fusion/hydrothermal reaction in the HD thermal power plant. The change in the crystal structure of the zeolite was confirmed using XRD and SEM, and the ammonia adsorption capacities of the synthesized zeolitic materials and a commercial zeolite (Na-A zeolite) were analyzed via an ammonia temperature-programmed desorption (NH₃-TPD) process. The SEM and XRD results revealed out the zeolitic materials from the coal fly ash maintained a hexagonal Linde-type crystal structure similar to that of Na-A zeolite, but the crystallinity of the synthesized zeolitic material was reduced due to impurities. The NH₃ adsorption capacity, determined from the NH₃-TPD analysis of was 1.122 mmol/g of the synthesized zeolitic material, which was lower than the NH₃ adsorption capacity of the Na-A zeolite.

• Geotechnical Engineering
• /
• v.12 no.1
• /
• pp.73-86
• /
• 1996

In this study, the possibility of the utilization of coal ash as earthwork materials is investigated. For this purpose, some laboratory experiments were carried out. The samples used in these tests are fly ash(FA), bottom ash(BA), coal ash dropped into ash pond(FA:BA=8:2), and mixed coal ash(FA:BA=5:5), which were discharged as a by-product at Yong-Yeul thermoelectric power plant, and general road filling materials. And for the deformation analysis of coal ash reclamation ground, several hyperbolic model parameters were determined by triaxial compression test. As a result of this study, coal ash has excellent engineering properties such as strength parameters comparing with general soils of the same grain size, especially in case of being used as backfill materials and reclamation materials on soft ground, and coal ash is superior to general earthwork materials in engineering properties becasuse of self hardening behaveiour, light weight property, etc.