• Korean Journal of Environmental Agriculture
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• v.41 no.4
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• pp.223-229
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• 2022

BACKGROUND: Mining activities, smelter discharges, and sludges are the major sources of heavy metal contamination to soils. The objective of this study was to determine the efficiency of magnetite and bottom ash derived from coal ash in remediating As-contaminated soil. METHODS AND RESULTS: An incubation experiment was conducted for 10 weeks. Magnetite and bottom ash at different rates and ratios were applied to each plastic bottle repacked with 1,000 g of dried As-contaminated soil. After 3-weeks of incubation, the concentrations of available As were measured by using Mehlich-3, SBET, and sequential extraction methods. All of the subjected soil amendments resulted in significant decreases in available As concentration compared to the controls. The addition of magnetite at the highest rate was the best to stabilize As in the soils; however, the values of As concentration varied with the extraction methods. CONCLUSION(S): To ensure the stabilization accuracy of heavy metals in soil, both single and sequential extractions are recommended. The magnetite derived from fly coal ash can also be applicable as a heavy metal stabilizer for the As-contaminated soil.

• KEPCO Journal on Electric Power and Energy
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• v.5 no.4
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• pp.287-293
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• 2019

Domestic thermal power plant fly ash is at a situation which emissions are increasing every year. Comparing to Fly Ash, Bottom Ash is only 15 %, but it's recycling rate is low, so most of them is being buried in the ground. However, landfill site of every power plant is full, and the construction of a new landfill is difficult. To solve this problem, the best solution is to use Bottom Ash as a landfill of large-scale civil engineering projects. The purpose of this study was to investigate the compression strength behavior characteristics of weak clay and uniaxial compression test to examine the applicability of surface soil solidification method of mixed soils mixed with industrial waste coal ash and weak clay which is buried in bulk. As a result of the test, the fluidity of the Mixed soil with clay + bottom ash + cement was improved to 200 mm at the water content of 91-92 %. The uniaxial compressive strength was also good for the mixed soils (clay + bottom ash + cement) meeting the required strength of 159 kN/㎡ at 28 days. However, the other samples did not meet the required strength. In this study, the prediction equations for the compression strength behavior by cement and curing period were presented.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.6
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• pp.533-539
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• 2014

Mine wastes such as acid mine drainage (AMD) can cause the detrimental effects on surrounding environment, thereby eventually threatening human health. Main objective of this study was to evaluate the neutralizing effect of fly ash (FA) as a stabilizing material AMD. Field plot was constructed in a coal waste depot which has caused aluminium-whitening adjacent to the stream. Different mixing ratios of FA were applied on a top of the soil, and then the physicochemical properties of runoff and soil were monitored. Constructed plots were as following: control (mine waste only (W)), mine waste + 20% ($w\;w^{-1}$)of FA (WC20M), mine waste + 40% ($w\;w^{-1}$)of FA (WC40M), and WC40M dressed with a fresh soil at the top (WC40MD). Result showed that initial pH of runoff in control was 5.09 while that in WC40M (7.81) was significantly increased. For a plot treated with WC40M, the concentration of Al in runoff was decreased to $0.22mg\;L^{-1}$ compared to the W as the control ($4.85mg\;L^{-1}$). Moreover, the concentration of Fe was also decreased to less than half at the WC40M compared to the control. Application of FA can be useful for neutralizing AMD and possibly minimizing adverse effect of AMD in mining area.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.4
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• pp.514-519
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• 2020

In this study, cement clinkers were sintered at each temperature by replacing some of the clay components of cement clinkers with coal materials. The mineral phase change of sintered cement clinker was quantitatively analyzed by XRD-Rietveld method. As the sintering temperature of cement clinker increased, the amount of belite decreased, the amount of alite increased, and the amount of free-CaO decreased. The form of alite and belite could be distinguished at sintering temperature of 1450℃ or higher. The crystal size was greatly increased at 1500℃ sintering. It was confirmed that the excessive sintering was progressed. Free-CaO decreased with the increase of sintering temperature. At 1450 ℃ or higher, it was less than 0.5%. In 1450℃ or greater, it is determined that enough sintering is included. Therefore, the application of fly ash as a raw material of cement clinker was judged to be usable as a source of chemical components of alumina and iron raw materials.

• Journal of the Korea Institute of Building Construction
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• v.22 no.6
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• pp.641-649
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• 2022

This study aims to completely develop a non sintered cement mortar using industrial by-products. To replace Portland cement, blast furnace slag, circulating fluidized bed fly ash, and pulverized coal fly ash were used, and natural aggregates were substituted with ferronickel slag. To understand the characteristics of the non sintered cement mortar to which ferronickel slag is applied, an experiment was conducted by classifying the particle size. Fluidity and workability were confirmed through the flow test, and bending and compressive strength tests were conducted at 3, 7, and 28 days of age. In addition, durability was identified through a chloride ion penetration test. Through the study, it is judged that the binder, which completely replaced cement and aggregate, has high potential of being used as a construction material. Notably, it was confirmed to be advantageous for strength and durability.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.3
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• pp.276-281
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• 2023

Water pipes manufactured using existing Portland cement suffer from the problem of rapid deterioration and reduced durability due to the hydration product of cement being vulnerable to acids. Therefore, in this study, water pipes were manufactured using slag and fly ash, which are industrial by-products from various industries, and their characteristics were analyzed. As a result of the experiment, slump in unhardened concrete tended to increase due to the ball bearing action of fly ash, and the amount of air was reduced due to unburned coal, indicating that measures for frost resistance were needed. In addition, the initial strength of the compressive strength was increased through steam curing, and the results were equal to or better than OPC when mixing more than 50 % of slag. The acid resistance results showed that the mass reduction rate was less than 5 %, showing excellent durability performance, and the bending failure load of the water pipe also exceeded the KS standards, so it is judged to be commercializable.

• Journal of Korean Society for Atmospheric Environment
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• v.31 no.2
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• pp.118-130
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• 2015

Fine dust containing iron compounds is of current interests in metro subway as well as large scale industries including iron manufacturing and smelting works. This work attempts to find a new design of magnetic filter module for iron dust capture. It simulated the vertical rectangular duct with metal mesh which might promote electric fields in the duct space. A lab test using coal fly ash composed of 8.66% Fe with the most form of $Fe_3O_4$ and $Fe_2O_3$ showed capability of magnetic collection. It showed the capture efficiency with 80~93% for $PM_{2.5}$ depending on magnetic intensity. Ferromagnetic wire mesh contributed up to 50% of collection increment.

• Applied Chemistry for Engineering
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• v.19 no.5
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• pp.533-538
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• 2008

In order to enhance the adsorption capacity of $CO_2$, a commercial zeolite and coal fly ash were chemically modified with alkali cations (Li, K) and alkaline-earth cations (Ca, Mg). Adsorbents containing Ca and Mg showed slightly lower surface areas. The adsorption capacity at the ambient temperature was highest with Ca, then in order of Mg, Li, and K. On the contrary, regeneration efficiency of the adsorbents with Ca and Mg was relatively low, because Ca and Mg cations had stronger affinity of carbon dioxide. The affinity between cations and $CO_2$ molecule also may improve the selectivity in favor of $CO_2$ adsorption.

• Journal of Korean Society on Water Environment
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• v.28 no.5
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• pp.723-728
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• 2012

In this study, zeolites were synthesized by a fusion and a hydrothermal methods using a coal fly ash and a waste catalyst. The recovery performance of metal ions on the structure property of synthetic zeolites was evaluated as comparing the adsorption kinetics (Lagergen 2nd order model) and isotherm (Langmuir model) of $Co^{2+},\;Ni^{2+}$, and $Cu^{2+}$ ions. The synthetic zeolites (Z-C1 and Z-W5) were similarly assigned to XRD peaks in a reagent grade Na-A zeolite (Z-WK : $Na_{12}Al_{12}Si_{12}O_{48}\;27.4H_2O$). Adsorption rates of Z-W5 and Z-C1 were in the order of $Cu^{2+}\;>\;Co^{2+}\;>\;Ni^{2+}\;and\;Ni^{2+}\;>\;Cu^{2+}\;>\;Co^{2+}$, respectively. They had influenced upon structure properties of zeolite. Selectivities of metal ions and maximum equilibrium adsorption capacities, $q_{max}$, in Z-C1 and Z-W5 were in the order of $Ni^{2+}$ (127.9 mg/g) > $Cu^{2+}$ (94.7 mg/g) > $Co^{2+}$ (82.6 mg/g) and $Cu^{2+}$ (141.3 mg/g) > $Co^{2+}$ (122.2 mg/g) > $Ni^{2+}$ (87.6 mg/g), respectively. The results show that the synthetic zeolites, Z-C1 and Z-W5, are able to recover metal ions selectively in wastewater.

• Korean Chemical Engineering Research
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• v.48 no.6
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• pp.784-790
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• 2010

VOCs such as acetone, benzene, toluene, ethylbenzene were adsorbed in a fixed-bed adsorber using zeolite synthesized from coal fly ash and 4 kinds of activated carbon at 101.3 kPa. The adsorber was operated batchwise with the charge of 5 g adsorbent to obtain the breakthrough curve of VOCs. Experiments were carried out at $40^{\circ}C$, nitrogen flow rate of $70cm^3/min$ and sparger temperature of $30^{\circ}C$. The deactivation model was tested for these curves by combining the adsorption of VOCs and the deactivation of adsorbent particles. The observed values of the adsorption rate constant and the deactivation rate constant were evaluated through analysis of the experimental breakthrough data using a nonlinear least square technique. The experimental breakthrough data were fitted very well to the deactivation model than the adsorption isotherm models in the literature. Also, adsorption capacities of adsorbents were obtained from the breakthrough curve to observe the correlation between adsorption capacity and the physical properties of VOCs.