In this study, it is conducted analysis of water absorption of artificial lightweight aggregate using coal ash. For absorption of water, the artificial lightweight aggregate was submerged for 24hours or in conditions of high temperature(100℃) and normal pressure. And it was measured water absorption ration and density( in conditions of oven-dry and saturated surface dry).

More than 8 M tons of coal ash is generated from coal-fired thermal power plants every year, and the generation rate of coal ash has been increasing steadily recently. However, the recycling rate of coal ash is about 70%. It is time to introduce the beneficial use of coal ash. Much coal ash is used in mining applications and reclamation sites in the EU and the U.S. However, coal ash cannot be used at mine reclamation sites in Korea because of its legal limitations due to environmental concerns. Therefore, in this research, the eco-friendly use of coal ash at mine reclamation sites in Korea is presented. To develop the eco-friendly use of coal ash at mine reclamation sites in Korea, this study examined the beneficial use of coal ash at mines and the environmental issue of the specific use of coal ash at mine reclamations sites and carried out case studies on the use and management systems of coal ash in overseas countries and investigation of the present use of coal ash at mine reclamation sites in Korea.

In this study, we looked into the levels and distribution characteristics of harmful substances found in imported coal ash to identify their possible impacts on the environment and human body in the process of recycling and to develop plans for their proper management. To this end, organic pollutants including heavy metals were analyzed from 19 samples of imported coal ash, and their potential impact on the environment was evaluated. To investigate the characteristics of the heavy metal content in the coal ash, a leaching test was conducted, and the result showed that the heavy metal concentrations in the coal ash were far lower than the permitted levels of hazardous substances in designated waste in Korea. In addition, a content analysis showed that the heavy metal content was lower than the level prescribed in the standards for area II levels of soil contamination. Since coal ash is recycled in cement kilns, levels of Pb, Cu, and Cd in the cement kilns were reviewed and compared against permitted levels of those heavy metals in other alternative fuels. Levels of Pb, Cu, and Cd in the coal ash were comfortably within the acceptable limits by Korean standards, but the level of arsenic was close to the limit. Given the fact that arsenic leached from the coal ash recycling process could have an adverse impact on both the environment and the human body, it is therefore necessary to monitor arsenic leaching from coal ash continuously . Levels of other substances that could be contained in coal ash, such as dioxin, PCBs , and PAHs, were also measured. The measurements showed that the levels of these substances were generally low or undetectable; therefore, the environmental impact of organic pollutants from coal ash recycling was considered insignificant.

석탄화력발전 부산물인 석탄회의 희유 금속 재활용을 위한 기반 연구로서 9개 발전소의 석탄회를 대상으로 화학적 및 광물학적 특성을 분석하였다. 석탄회의 희유원소 화학조성은 전반적으로 셰일의 평균 조성과 부합하며, 국외 석탄회와 차이도 거의 없다. 그러나 국산 무연탄 비산재와 수입 유연탄 비산재는 무기원소 조성에서 약간의 차이가 있으며, 무연탄 비산재의 미연 탄소 함유량이 매우 높다. 바닥재와 비교하여 친황원소들이 비산재에 부화되는 경향이 있다. 규산염 유리가 주요 고상이며, 석영, 일라이트(백운모), 멀라이트, 자철석, 생석회, 경석고가 광물로 함유되어 있다. 규산염 유리는 Al과 Si가 주성분이고, Ca, Fe, K, Mg가 다양한 비율로 함유되어 있다. 규산염 유리는 다공성 구형 또는 비정형 부석질 입자들이며, 흔히 잔존 광물이나 산화철구, 또는 다른 유리입자들과 융접되어 있다. 산화철구 입자는 급속 성장한 산화철 미세 입자와 유리 기질로 구성되어 있다. 석탄회로부터 유가 금속 재활용을 위해서는 이상의 화학조성, 미세조직, 광물학적 특성들이 고려되어야 한다.

In this work, we constructed the sulfur polymer cement(SPC) concrete using coal bottom ash from 4 thermal power stations in korea and investigated their practical data for production of industrial construction compounds. To manufacture the SPC concrete, we used batch concrete mixer with the heating jacket using hot oil. Also, coal bottom ash was used as a fine aggregate below 2 mm. When the SPC concrete were produced with diverse sulfur concentration (15, 20, 25, 30 wt%), compressive strength properties were analyzed. We got the compressive strength of the maximum 60 MPa. These experimental results could be effectively applied to the recycling technology of coal bottom ash.

A general method to expand the urban green space is to utilize the artificial ground that is unutilized in cities, such as buildings and rooftops. The processing technology of bottom ashes in thermal power stations shows a tendency to change from the wet process to the dry process. The dry process bottom ashes, which arise from the new process, are expected to be utilized as light-weight artificial soil, because they are poor in water, salt, and unburned carbon, which are not the characteristics of the existing wet process bottom ashes, and have a lower density than general aggregate. This study shows that the coefficient of permeability, saturation bulk density, pH, EC, and organic matter content of dry process bottom ashes are similar to those of perlite. Therefore, we conclude that dry process bottom ashes can be utilized as artificial soil.

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.

Na-A zeolite (Z-Cl) was synthesized from coal fly ash, which is a byproduct of coal combustion for the generation of electricity. The adsorption of Cu2+ and Zn2+ions onto Z-C1 was investigated via batch tests over a range of temperatures (303.15 to 323.15 K). The resultant experimental equilibrium data were compared to theoretical values calculated using model equations. With these results, the kinetics and equilibrium parameters of adsorption were calculated using Lagergren and Langmuir-Freundlich models. The adsorption kinetics revealed that the pseudo second-order kinetic mechanism is predominant. The maximum adsorption capacity (qmax) values were 139.0-197.9 mg Zn2+/g and 75.0-105.1 mg Cu2+/g. Calculation of the thermodynamic properties revealed that the absorption reactions for both Cu2+and Zn2+ were spontaneous and endothermic. Collectively, these results suggest that the synthesized zeolite, Z-C1, can potentially be used as an adsorbent for metal ion recovery during the treatment of industrial wastewater at high temperatures.

This study is purposed to analyze the compressive strength development with different produce of fly ash in order to develop cementless concrete. As a results, compressive strength of cementless mortar is related to effect on compressive strength development for the type of fly ash.

The recovery potential of rare earth elements (REE) in coal ash was evaluated in this study. The previous researches were reviewed, and the physicochemical analysis of coal ash collected from a thermal power plant in Korea was conducted. According to the results of particle-size distribution, fly ash could be classificed as a fine-grained soil by unified soil classification system, and showed a uniform particle size distribution. The particle size of bottom ash was a coarse grained soil and the particle-size distribution was well graded compared to that of fly ash. However, there was no significant difference in the physicochemical composition between both the ashs and particle-size. Although REE was not found in the coal ash specimens used in this study, various valuable metallic compounds were observed. The silicate compounds showed the highest contents being 50% (by wt.), followed by 20 and 10% in aluminum oxide and iron hydroxide. There were also the trace elements in oxide forms (e. g., Ca, Mg, K). Unlike previous researches there are no REE detected in the coal ash specimens used in this study. The composition of ash depends on the coal used in the power plant and the detection limits of analytic instruments may be critical.

Zeolite 4A was synthesized by fusion method from coal fly ash discharged at the thermal power plants. The synthesized zeolite(FAZ) was characterized through particle size analyzer, XRD, XRF and SEM. N2 adsorption-desorption measurement was used to examine surface and pore structures. The adsorption experiments were carried out under dynamic conditions of trace SO2 in N2 to investigate SO2 adsorption capacity of FAZ. The experiments were conducted to characterize the breakthrough characteristics of SO2 in a fixed bed under different operating conditions including temperature(50-125℃), concentration of SO2(3000-10000 ppm) and FAZ with 4 kinds of commercial zeolite. The adsorption capacity of FAZ was 53.84 mgSO2/g adsorbent, larger than that of the same type commercial zeolite(WK4A).

The adsorption performance of cupper and zinc ions(Cu2+ and Zn2+) in aqueous solution was investigated by an adsorption process on reagent grade Na-A zeolite(Z-WK) and Na-A zeolite (Z-C1) prepared from coal fly ash. Z-C1 was synthesized by a fusion method with coal fly ash from a thermal power plant. Batch adsorption experiment with Z-C1 was employed to study the kinetics and equilibrium parameters such as initial metal ions concentration and adsorption time of the solution on the adsorption process. Adsorption rate of metal ions occurred rapidly and adsorption equilibrium reached at less than 120 minutes. The kinetics data of Cu2+ and Zn2+ ions were well fitted by a pseudo-second-order kinetics model more than a pseudo-first-order kinetics model. The equilibrium data were well fitted by a Langmuir model and this result showed Cu2+ and Zn2+ adsorption on Z-C1 would be occupied by a monolayer adsorption. The maximum adsorption capacity(qmax) by the Langmuir model was determined as Cu2+ 99.8 mg/g and Zn2+ 108.3 mg/g, respectively. It appeared that the synthetic zeolite, Z-C1, has potential application as absorbents in metal ion recovery and mining wastewater.