• Korean Chemical Engineering Research
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• v.54 no.2
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• pp.234-238
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• 2016

Solid ash-free coal (AFC) samples recovered from solvent-extracted solution by vacuum drying, dilution precipitation and spray drying methods were compared in terms of physical properties and chemical structure. AFC was prepared by using Kideco coal (Indonesian sub-bituminous coal) and polar N-methyl-2-pyrrolidone (NMP) solvent as raw materials. The physical properties of the AFCs were characterized with proximate, ultimate, and calorific value analysis. In analyzing the chemical structure, FTIR and NMR were used. the proximate analysis showed much reduced ash in the AFCs compared to parent raw coal. The FTIR result showed that the extraction solvent was not fully removed from the AFC prepared by vacuum drying. However, the solvent was not detected in the AFC recovered by using dilution precipitation. Dilution precipitation has advantages over the other two methods, since it can be done at relatively low temperature and separate ash-free coal from extraction solvent more effectively.

• Korean Journal of Soil Science and Fertilizer
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• v.20 no.4
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• pp.309-314
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• 1987

This study was conducted to examine mineralogical aspects on anthractite and bituminous coal-fired power-plant ashes as a source of mineral fertilizer. Fly ashes contain dominant amounts of silica and alumina and considerable quantitites of potassium and boron. However, potassium and silica present in unavailable forms for plant growth. X-ray, DTA, and IR analysis of ash particles indicated the formation of new mineral, mullite with shape of which were spherical in the surface morphologies of SEM. Detailed SEM investigation showed the presence of imbedded blocky shape silicate material.

• Journal of environmental and Sanitary engineering
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• v.14 no.4
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• pp.165-171
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• 1999

A study on the synthesis of zeolite 4A using the bituminous coal fly ash from power plant was carried out. This study aims to investigate possibility for detergent builder with synthesized zeolite. It was examined at the crystallization conditions of atmospheric pressure and that of pressurization. The synthesized zeolite was proved to be Zeolite 4A type by means of the XRD and SEM analysis, and then the synthesized zeolite was used as an absorbent the remove the $Ca^{2+}$ ions in the water. In this study, commercial zeolite and synthesized zeolite reached equilibrium within 10 and 30 minutes respectively. The amount of $Ca^{2+}$ ions exchanged by the commercial zeolite, atmospheric pressure zeolite (zeolite A) and pressurized zeolite(zeolite PA) were 391mg/L(as $CaCO_3$), 323mg/L(as $CaCO_3$) and 355mg/L(as $CaCO_3$) respectively.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.159-162
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• 2000

The purpose of this study is to develope an accurate procedure for measuring the glass content of fly ash produced by bituminous coal to assist in predicting their behavior in concrete. Quantitative mineralogical compositions of fly ashes were obtained by internal standard method using powder X-ray diffraction analysis. In the X-ray diffraction method, the specimen and standard fluorite were cautiously mixed and pulverized to 22$\mu$m in wet process so as to avoid the prefered orientation of the crystal and microabsorption effect of X-ray. calibration curve were fitted for several references peaks of four phases:$\alpha$-quartz. mullite, magnetite, hematite. The amount of glass was calculated by subtracting the amount of crystal phase and loss on ignition from the total amount. Glass content determined with this method ranged from 66.7 to 75.wt%.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.10
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• pp.997-1003
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• 2011

In order to investigate devolatilization characteristics for ashless coal with relatively low ash content and high heating value, an experiment was performed in different bed configurations of TGA and DTF(Drop Tube Furnace) at atmospheric pressure condition. The heating rate was $10^{\circ}C$/min up to $950^{\circ}C$ in TGA, while the temperatures of DTF varied from 500 to $1300^{\circ}C$ in step of $200^{\circ}C$. A weight loss and particle temperature were obtained to determine devolatilization kinetics. The kinetic parameters including an activation energy and pre-exponential factor for ashless coal were obtained using Coats-Redfern method in TGA and single step method in DTF. Furthermore, the devolatilization kinetics of the ashless coal were compared with the results of different kinds of conventional coal such as sub-bituminous and bituminous. The results show that the activation energy of devolatilazation for ashless coal is lower than those of others in fixed and entrained conditions.

• Journal of Energy Engineering
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• v.19 no.2
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• pp.136-142
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• 2010

Combustion reactivity and thermal behavior of two imported coals used as a pulverized fuel of commercially thermal power plant were investigated by thermogravimetric analysis (TGA) and large scale test furnace of 200 kg/hr. TGA results showed that combustion efficiency of high moisture coal has lower than reference coal due to the slow combustion completion rate although it has the low ignition temperature, and activation energies of high moisture coal with 79 kJ/mol for overall combustion was higher than reference coal of 53 kJ/mol. Test furnace results ascertained that flame of black band of high moisture coal during the combustion in boiler broke out compared to reference coal and then it becomes to unburned carbon due to the less reactivity and combustion rate. But, Blending combustion of high moisture coal with design coal of high sulfur are available because sulfur content of high moisture coal was too low to generate the low SOx content in flue gas from boiler during the combustion. The ash analysis results show that it was not expected to be associated with slagging and fouling in pulverized coal fired systems due to the low alkali metal content of $Na_2O$ and $K_2O$ compared to bituminous coal.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.7
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• pp.675-681
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• 2012

The char oxidation characteristics of ashless coal with a relatively low ash content and high heating value were experimentally investigated at several temperatures (from $900^{\circ}C$ to $1300^{\circ}C$), in various oxygen concentrations (from 10% to 30%) under atmospheric pressure in a drop tube furnace. The char reaction rate was calculated from the exhaust gas concentrations (CO, $CO_2$) measured by FT-IR, and the particle temperature was measured by the two-color method. In addition, the activation energy and pre-exponential factor of ashless coal char were also calculated based on the Arrhenius equation. The results show that higher temperature and oxygen concentration result in a higher reaction rate of ashless coal, and the activation energy of ashless coal char is similar to that of bituminous coal.

• Korean Journal of Soil Science and Fertilizer
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• v.28 no.2
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• pp.130-134
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• 1995

To investigate the influence of coal fly ash treatment on the heavy metal content in the infilteration water, 12t/10a/year of fly ash(Anthracite and Bituminous) were applicated at two paddy fields of different textured soils, clay loam and sandy loam, for 3 and 2 years, respectively. The infilteration waters were collected 30, 60 and 100cm of soil depth and the heavy metal contents were measured. In the paddy field of clay loam, the content of Zn in the infilteration water were increased with fly ash treatment and increasing soil depth, but it didn't show any significance. In the clay loam soil, successive application of fly ash for 3 years brought to increase Pb, Zn content in the infilteration water, Pb content was the highest at 100cm of soil depth, but the content of others were lower than non-treatment. In the paddy field of sandy loam, successive application of fly ash for 2 years increased Cd, Ni and Mn content in the infilteration water at anthracite ash application, but the contents of other elements were similar or lower than non-treatment.

• Journal of the Korea Organic Resources Recycling Association
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• v.26 no.1
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• pp.39-45
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• 2018

Research on FA(Fly ash) is actively carried out, while the research on BA(Bottom ash) is not so, and research on BA recycling field is urgently required. Therefore, in this study, we investigated the lightweight and thermal insulation characteristics of BA mortar by comparing BA mortar made with porous dry BA(air-cooled) and general mortar. To investigate the lightweight of BA, density test, unit volume mass test and SEM(Scanning Electron Microscope) test were performed. BA mortar and general mortar molds were prepared for the thermal insulation test at room temperature and humidity environment determined by KS A 0006 and they were dried at the temperature of $105{\pm}2^{\circ}C$ until the weight became constant. As a result of the lightweight test, the lightweight of BA mortar is about 30% lighter than the general mortar. Therefore, BA is expected to contribute to reduce the building load when used as building material. As a result of thermal insulation test, the thermal conductivity of BA mortar is about 30% better than that of general mortar.

• Korean Journal of Soil Science and Fertilizer
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• v.25 no.3
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• pp.249-254
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• 1992

This research was conducted to investigate the effects of fly ash applications on growth and yield parameters of corn (Zea mays L.), and soil chemical properties. Corn height at silking stage, and height and dry matter ratio at harvesting stage were enhanced by applications of fly ashes derived from bituminous coal and anthracite, respectively. Effects of fly ash treatment on growth parameters of corn were varied with kinds and levels of fly ash application and growth periods, but relatively small without revealing a major negative effect as compared to the control. Yield of corn was increased by applying fly ash of anthracite origin, but other yield components were not influenced negatively by fly ash treatment. Soil total carbon contents, cation exchange capacity, and phosphorus contents of soils sampled after harvest of corn were significantly increased by fly ash treatment, although there were slightly different effects according to kinds and levels of fly ash application. Exchangeable cations of soils were varied within an experimental error range. Phosphorus taken up by corn was enhanced by treating fly ash of the bituminous coal to the soil and there were a positive correlation between phosphorus uptake and soil Phosphorus level. Cation uptake by corn was changed a little, but no significant reduction was observed in cation uptake due to fly ash treatment. It seems to be difficult to figure out the mechanism of fly ash effects on growth and nutrient uptake by corn with one year field experiment, however treatment of fly ash enhanced some parameters of growth and yield, and nutrient uptake by corn without revealing any major negative effects. To determine the value of fly ash as a fertilizer source, continuous researches under various soil and crop conditions were considered to be necessary.