• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.11a
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• pp.156-157
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• 2014

Inorganic binding material was made by recycled resource and its applicability as pile-filling material was examined. The result was that the material had same liquidity with the liquidity of OPC and high reactivity with site soil. According to dynamic/static loading tests by site test-construction, the inorganic binding material met both design bearing capacity and settlement. Since the inorganic binding material showed same or better performance than OPC, the utilization possibility of the inorganic binding material made of recycled resource as pile-filling material was verified.

• Resources Recycling
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• v.20 no.1
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• pp.54-60
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• 2011

The spherical artificial aggregates (AAs) with a diameter of 8 mm, which contains fly ashes discharged from the fluidized bed combustion in a thermal power plant and clay were manufactured by direct sintering method at $1050{\sim}1250^{\circ}C$ for 10 minutes. The effect of fly ash contents on the bloating phenomenon in the AAs was analyzed. The AAs containing fly ash of the amount under 50 wt% showed the black-coring and bloating phenomena. The AAs containing fly ash of the amount over 5Owt%, however, the specific gravity was increased and the color of specimens fully changed to black. These color change phenomena were caused from the formation of FeO by the reduction reaction of almost $Fe_2O_3$ component by the excessive reducing atmosphere formed simultaneously with the rapid emission of the gases generated from the high contents of unburned carbon of with increasing the added fly ash amount. Specific gravity was decreased as fly ash contents increased in the case of sintering at the same temperature condition. Water absorption of all specimens except of the specimens containing 10 wt% fly ashes decreased with increasing sintering temperature. These were because a liquid phase was formed as the increasing the sintering temperature. In the case of the specimens manufactured in this study containing fly ashes discharged from the fluidized bed combustor in a the thermal power plant and 10~90 wt% of clay, the specific gravity was 0.9~1.8 and the water absorptivity was 8~60%, therefore it is considered that those results can be applied to the light or heavy aggregates.

• Resources Recycling
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• v.29 no.6
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• pp.125-132
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• 2020

Enrichment possibilities for recovering rare earth elements contained in coal bottom ash generated from domestic circulating fluidized bed combustion (CFBC) were identified. The transport characteristics of the REEs according to the separation and removal of major minerals were evaluated using sieving and leaching process. The main minerals of bottom ash were identified as anhydrite, magnetite, and quartz, and this was confirmed as a 30% of REE content of the world's average coal ash REE value (404 ppm) as a result of the difference in the combustion characteristics of power plants (REE contents in starting material: 123 ppm). More than 90% of the REEs contained in the bottom ash were found to move mainly with magnetite, and less than 10% of the components were found to move with the quartz. Therefore, In order to recover rare earth elements from coal bottom ashes generated from CFBC boiler, it is necessary to select the main rare elements such as magnetite and develop a pretreatment and concentration process.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.22 no.5
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• pp.254-259
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• 2012

The mechanical property enhancement was studied using fly ash produced from fluidized bed type boiler in power plant, which contains a lot of Ca component being used to carbonate for $CO_2$ fixation in the lightweight aggregates made of cement and some portion of fly ash as a cement substitution under the supercritical condition. Specimens having various fly ash substitution rates and curing periods were carbonated under the supercritical condition at $40^{\circ}C$. The weight change rate, carbonation rate by TG/DTA analysis, 1% Phenolphthalein test, specific gravity and mechanical compression strength test were performed to observe the mechanical property enhancement of the cemented materials after carbonation under the supercritical condition and to make sure those could be classified as lightweight aggregates having specific gravity under 2.0.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.3
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• pp.284-291
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• 2016

To evaluate the properties of inorganic composites using a great quantity of high-calcium fly ash generated in combined heat and power plants, high-calcium fly ash and F-class fly ash commonly used as concrete admixtures were substituted with binding materials to examine changes of fluidity and compressive strength depending on the substitution ratio for each curing temperature. According to the experimental result, CFA-mixed mortar showed a tendency to reduce its flow unlike FFA-mixed mortar as the substitution ratio was increased, but its flow loss showed smaller than FFA as time passed. As a result of examining compressive strength depending on mixing FA, FFA-mixed mortar had an optimum range within 50% when curing at ambient temperature, but it was found that the compressive strength is reduced when mixing CFA. When curing at high temperature, FFA did not relatively have a great effect on the substitution ratio, but CFA could expect a strength enhancement effect compared with 100% of OPC when using within 25% of binding materials.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.3
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• pp.152-160
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• 2013

The purpose of this study is to enhance the mechanical strength of specimens containing fly ash from fluidized bed type boiler, which the recycling rate will be eventually increased. Specimens containing fly ash in a certain portion were made and aged for 3, 14, and 28 days. Specimens were carbonated under the supercritical condition at $40^{\circ}C$. The carbonation process under the supercritical condition was performed to enhance the mechanical property of specimens by filling the voids and cracks existing inside cement specimen with $CaCO_3$ reactants. The additional aging effect after the supercritical carbonation process on mechanical strength of specimens was also investigated by comparing the compressive strength with and without 7 day extra aging. Under the supercritical condition and additional 7 day aging specimens were very effective for enhancement of mechanical strength and compressive strength increased by 44 %.