• Economic and Environmental Geology
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• v.32 no.6
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• pp.575-584
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• 1999

Through alkaline hydrothermal activation processes, zeolite minerals were synthesized from fly ashes produced at Youngwol and Boryoung power plants. The syntheses were performed in a closed teflon vessel with a teflon-coated magnetic bar for continuous stirring during the reaction periods. The experiments were caeeied out at three different reaction temperatures ($100^{\circ}C$,$200^{\circ}C$, and $250^{\circ}C$), with varying NaOH concentations (0.5~8N) and reaction time (24 to 288 hours). Mineralogical characterization of the reaction products indicated that Na-p1, analcime, and hydroxysodalite were dominant zeolites formed from the both fly ashes at the given experimental conditions, The highest amount of zoelites produced from the Youngwol and Boryoung fly ash were:60 and 45wt%for Na-P1, 70 and 45wt% for analicime, 50 and 40wt% for hydroxysodalite, respectively. A small amount of zeolite A was present in NaP-dominant dample is about 250 meq/100g. This suggests the possibility of its utilization as an ion-absorbent.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.15 no.1
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• pp.97-104
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• 1986

This is to supply the basic data for saving energy and the appropriate way of waste disposal. The amount of waste disposed and its heat after burning is guessed to get conclusions. 1. The amount of disposable waste in 1990 in Seoul area is expected to be 2.2kg per man/day, coal ashes (YONTAN) 0.7kg, non-coal ashes 1.5kg. 2. The amount of waste combustible and heat after burning will be increased, and it is useful when the waste has Less than $70\%$ of water. 3. The method to collect waste should be specially organized, because most of the waste collected In Korea Is wet. 4. As the heat emitted from mass burning is $4\times10^{12}kcal/y$ in 1985, it is considered to be in senses of energy saving and the rationnal way of waste disposal. 5. Special concern is needed because the environment contaminated will be polluted in result of burning.

• Journal of the Korea Institute of Building Construction
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• v.17 no.2
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• pp.183-189
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• 2017

The aim of the research is to provide rheological properties of cement paste with various qualities of coal ash including fly ash, raw ash, and reject ash. Generally, fly ash is the well known supplementrary cementitious materials for concrete and is used to improve various properties. Although fly ash is obtained as a byproduct of fire powder plant, still reject ash is wasted from raw ash. In this research, thus, to provide a fundamental information on using not only fly ash but also raw ash or reject ash for cementitious materials, a rheological properties of cement paste was studied with three different coal ash. This research was conducted from particle conditions of three different coal ashes to rheological properties in cement paste phase. According to the expeirment, reject ash was consisted with large and coagulated particles although fly ash was consisted with a small and spherical shaped particles. based on the particle conditions of various coal ashes, rheological behaviors were tested, and it was shown as the coal ashes improved the fluidity of cement paste. Specifically, depending on the particle distributions of cement paste, it is considered that the viscosity of paste can be controlled.

• Resources Recycling
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• v.19 no.2
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• pp.3-9
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• 2010

In most coal fired power plants, fly ashes collected from each of hoppers in the electrostatic precipitator are transported and stored in a silo. However the properties of the fly ashes collected from each of hoppers in electrostatic precipitator varies with the distance of the collection field from the boiler. The more distance hopper gets fly ash with larger specific surface area. Therefore, in electrostatic precipitator the hopper itself is expected to have the effect of classifying fly ashes. This study examines the physical, chemical and mineralogical properties of fly ash, collected from each of hoppers attached to an electrostatic precipitator in the coal fired power plant and looks into the possibility of the electrostatic precipitator being used as a classifier. Also, the study reviewed the possibility of acquiring high quality fly ash.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.1
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• pp.177-186
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• 1992

In this study, the proper mixing ratio of fly ash to bottom ash is evaluated and bearing capacity of this mixed ash is examined for use of highway embankment and subgrade materials in large quantities. Independently of the mixing ratio of fly ash to bottom ash or the method of compaction test, maximum dry density ${\gamma}_{dmax}$ and CBR value of anthracite mixed coal ash is greater than that of bituminous mixed coal ash. The mixed ashes to contain more fly ash than that of which the ratio of fly ash to bottom ash is 8 : 2, are slaked readily when the water contents of compaction are greater than optimum moisture content O.M.C. The proper mixing ratios of fly ash to bottom ash are about 5 : 5 to 6 : 4. Coal ashes mixed with these ratios exhibit proper physical and geotechnical properties for use of highway embankment and subgrade materials, and enable coal ashes to be used in large quantities.

• Analytical Science and Technology
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• v.5 no.4
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• pp.433-441
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• 1992

Chemical composition and fusibility of coal ash were measured for 23 Korean anthracite coals. The relationship between chemical properties and fusion temperature of coal ash was investigated. The slagging and fouling in firing the pulverized coal for boiler was assessed for the coal samples. It was found that most ashes contained more than 80% of $SiO_2$ and $Al_2O_3$ whereas less than 1% of $Na_2O$. And also fusion temperature of ashes occured relatively higher for Korean coals. Therefore it can be predictable that the slagging and fouling formation has a little problem in a pulverized coal firing system. A base/acid ratio did show a good correlation with fusion temperature for these coal ashes.

• Asian Journal of Atmospheric Environment
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• v.4 no.2
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• pp.80-88
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• 2010

In order to offer a better understanding of air pollution of China as well as East Asia we attempted to characterize the chemical properties of the raw coal materials mined in China and their combusted bottom ashes generated from coal fired power plant. To this end, we measured the chemical characteristics of individual bottom ashes and feed coal fragments collected at a coal fired power generator which was operated with the raw coal dug at a coal mine in China. The chemical properties of these two sample types were determined by a synchrotron radiation X-ray fluorescence (SR-XRF) microprobe method. Through an application of such technique, it was possible to draw the 2D elemental maps in and/or on raw coal fragments and fired bottom ashes. The pulverized fine pieces of feed coal mainly consisted of mineral components such as Fe, Ca, Ti, Ca, and Si, while Fe was detected as overwhelming majority. The elemental mass of combusted bottom ash shows strong enrichment of many elements that exist naturally in coal. There were significant variations in chemical properties of ash-to-ash and fragment-to-fragment. Although we were not able to clearly distinguish As and Pb peaks because of the folding in their X-ray energies, these two elements can be used as tracers of coal fire origin.

• Resources Recycling
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• v.27 no.3
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• pp.39-47
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• 2018

According to Vietnam government establishes additional coal-fired power plants to secure generation capacity, emission of ashes is accelerating and processing them is urgent issue. This study targeted utilize fly ashes that occurred in circulating fluidized bed combusion (CFBC) power plant to use ground solidification materials. CFBC fly ashes are used to make solidification with ground granulated blast furnace slag (GGBFS), gypsum and cement. Then produced specimens by mixing with soft ground soil to confirm mixing effect of fly ash in solidification. As a result it was possible to find mixture design that is satisfied 3 MPa compressive strength in age 28 days and reduce weight loss rate over 50% in acid immersion test than plain specimens that using only ordinary portland cement.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.2
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• pp.59-66
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• 1988

At the present time, annually about 2 million tons of coal ashes are generated from thermal power plants in Korea, however, they are dumped into ash ponds mixed with sea water very expensively. In this thesis, engineering characteristics of bituminous and anthracite ashes are studied to utilize them as construction materials. The coal ash is non-plactic material and its grain size falls in the range of silt, but it has better soil engineering characteristics than general soils of same grain size. For example, the permeability, shearing strength, CBR, and consolidation properties match to that of sandy soils, moreover, strengthening by hydration can be expected with the lapse of year because of CaO presence in the components. So, utilizing those coal ashes in a productive way as reclamation or banking materials is expected.

• Geotechnical Engineering
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• v.11 no.2
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• pp.37-50
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• 1995

Recently, the treatment of coal ashes produced from thermal electric power plants have been raised as a serious problem in according to the increasing of electric power demand in Korea. This paper deals with a re -use method of coal ash as a fill material. Two domestic coal ashes are mixed with cement and lime to improve the mechanical properties of coal ash. The mechanical properties such as compressive strength, compressive deformation, permeability and frost heaving property are investigated in according to the change of admixture rate, curing temperature and curing time. In this study, it is found coal ash (fly ash+bottom ash) and fly ash with 2%~3% cement can be used as a fill material, respectively. It is also found the frost heaving properties of coal ash is effectively improved by the mixture of 6%~9% cement.