• Title, Summary, Keyword: 석탄 비산재

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Recycling of Coal Ash and Related Environmental Issues in Australia (호주의 석탄재 재활용 사례와 석탄재 재활용과 관련된 환경 문제)

  • Park, Jin Hee;Ji, Sang-Woo;Shin, Hee-Young;Jo, Hwanju;Ahn, Ji-Whan
    • Resources Recycling
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    • v.28 no.4
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    • pp.15-22
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    • 2019
  • Coal combustion products are generated during coal combustion and can be grouped into fly ash and bottom ash depending on collection methods. Fly ash and bottom ash can be recycled for various purposes based on their characteristics. Australia is the fourth largest coal production country in the world and reuses coal ash as cement, concrete, mine filler, and agricultural soil amendment. When fly ash is used as a supplement for cement and concrete, strength of the cement and the durability of the concrete can be improved. Use of coal combustion product for mine backfill stabilizes underground mine voids and stores a large amount of coal ash in the voids. Because of alkalinity of coal combustion products, it can neutralize acid mine drainage when used for mine backfill. In addition, it can be used as an agricultural soil amendment to improve acidity and physical properties of the soil and to supply plant nutrients. Recycling of fly ash in Australia will be further expanded because of its low trace element contents that can be toxic to plants and low radioactive element contents existing within soil background concentrations. The characteristics of coal combustion products are related to the characteristics of the coal used for combustion, and since Korea imports coal from Australia, Korean coal combustion products also can be recycled for various purposes.

Study on Reduction Unburned Carbon Contents in Low Quality Fly Ash from Vietnam (베트남 저품위 비산재의 미연탄소 함량 저감 연구)

  • Kim, Keeseok;Lee, Jaewon;Lee, Dongwon;Min, Kyongnam
    • Resources Recycling
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    • v.29 no.2
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    • pp.37-47
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    • 2020
  • According to Vietnam government establishes additional thermal power plant, processing the coal ash from power plant is urgent issue. This study targeted reducing unburned carbon contents in low quality fly ash to below 6% that according to international standards. As a result, the unburned carbon contents of low quality fly ash was high and irregular as 5.3~23.6%, and it was possible to reduce unburned cabon contents to under 6%, in case of unburned carbon contents below 9.8% ashes using air classification, in case of unburned carbon contents below 23.6% ashes using combined process composed of air classification and electrostatic separation.

Synthesis of Zeolite Using Discharged Fly Ash in an Industrial Complex in Ulsan (울산지역 공단에서 발생되는 비산재를 이용한 제올라이트 합성)

  • Lee, Chang-Han;Park, Jong-Won
    • Journal of Korean Society of Environmental Engineers
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    • v.33 no.5
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    • pp.301-306
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    • 2011
  • In this study, zeolite was synthesized by hydrothermal, fusion, and fusion/hydrothermal methods with fly ash, coal fly ash, and a waste catalyst discharged from thermal power plants and incinerator in Ulsan area. Coal fly ashes (CFAs) and a waste catalyst containing amounts of $SiO_2$ and $Al_2O_3$ ranging from 60.29 to 89.62 wt%. CFAs were mainly composed of quartz and mullite which were assayed by a XRD pattern. Zeolite could be synthesized by CFAs and the waste catalyst when all methods were used. Na-A zeolite (Z-C1, Z-C2, and Z-W5) are mainly synthesized by the fusion method from CFAs and the waste catalyst. Z-C1 and Z-C2 formed by-products, calcite peaks, which is caused by the content of CaO in CFAs and the addition of $Na_2CO_3$ for a synthetic process.

Rare Metal Chemistry, Microstructures, and Mineralogy of Coal Ash from Thermal Power Plants of Korea (화력발전소 석탄회의 희유금속화학, 미세구조, 광물학적 특성)

  • Jeong, Gi Young;Kim, Seok-Hwi;Kim, Kangjoo
    • Journal of the Mineralogical Society of Korea
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    • v.28 no.2
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    • pp.147-163
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    • 2015
  • Chemical and mineralogical properties of coal ash samples from the nine thermal power plants of Korea were investigated to acquire basic data for estimating the potential of rare metal recovery. Chemical compositions of coal ash were consistent with those of average shale and foreign coal ashes. However, there were small differences between the metal contents of domestic anthracitic and imported bituminous coal ashes. Unburned coal particles were much abundant in the ash of domestic anthracitic coal. Chalcophile elements were relatively enriched in the fly ash compared to bottom ash. Silicate glass was the major component of coal ash with minor minerals such as quartz, illite (muscovite), mullite, magnetite, lime, and anhydrite. Al and Si were the major components of the glass with varying contents of Ca, Fe, K, and Mg. Glass occurred in a form of porous sphere and irregular pumace-like grain often fused with iron oxide spheres or other glass grains. Iron oxide spheres were fine intergrowth of fast-grown iron oxide crystals in the matrix of silicate glass. Chemical, microstructural, and mineralogical properties would guide successful rare metal recovery from coal ash.

Adsorption Characteristics of Cobalt Ion with Zeolite Synthesized by Coal Fly Ash (석탄계 비산재로 합성한 제올라이트를 이용한 코발트 이온의 흡착특성)

  • Lee, Chang-Han;Suh, Jung-Ho
    • Journal of Korean Society of Environmental Engineers
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    • v.31 no.11
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    • pp.941-946
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    • 2009
  • Two types of synthetic zeolites, commercially used (Z-WK) and synthesized by coal fly ash (Z-C1), and raw coal fly ash(F-C1) were examined for its kinetics and adsorption capacities of cobalt. Experimental data are fitted with kinetic models, Lagergen $1^{st}$ and $2^{nd}$ order models, and four types of adsorption isotherm models, Langmuir, Freundlich, Redlich-Peterson, and Koble-Corrigan. Synthesized zeolite (Z-C1) which had 1.51 of Si/Al ratio was synthesized by raw coal fly ash from a thermal power plant. Adsorption capacities with three types of adsorbents, Z-WK, Z-C1, and F-C1, were in the order of Z-C1 (94.15 mg/g) > F-C1 (92.94 mg/g) > Z-WK (88.56mg/g). The adsorption kinetics of Z-WK and Z-C1 with cobalt could be accurately described by a pseudo-second-order rate equation. The adsorption isotherms of Z-WK and Z-C1 with cobalt were well fitted by the Langmuir and Redlich-Peterson equation. Z-C1 will be used to remove cobalt in water as a more efficient absorbent.

CO2 Capture Performance of Dry Sorbents Manufactured by Coal Fly Ash (석탄 화력발전소의 비산재를 이용한 건식 CO2 흡수제 제조 및 특성 연구)

  • Lee, Jae Hee;Wee, Jung-Ho
    • Journal of Korean Society of Environmental Engineers
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    • v.35 no.8
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    • pp.547-553
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    • 2013
  • This paper investigates the effect of coal-fired fly ash on dry $CO_2$ sorbents as the supports and additives. For this purpose, various kinds of dry sorbent were manufactured by mixing fly-ash, the primary $CO_2$ absorption components (NaOH and CaO) and water with their different combination. Thereafter, their $CO_2$ absorption performance and the property were analyzed. As a result, variation of absorption efficiency and temperature as well as $CO_2$ desorption of the sorbents are confirmed, which may be primarily ascribed to fly-ash addition to the sorbents. Particularly, fly-ash effect is strongly measured in the sorbent manufactured by mixing all four components (named WNCF sorbents). Absorption efficiency of WNCF sorbents at $550^{\circ}C$ is 35.6% higher than that of flyash free sorbent and desorption is solely observed in WNCF sorbents. Fly-ash in WNCF sorbents leads to increase the dispersity of $CO_2$ absorption components and decrease their particle size in the sorbents. In addition, fly-ash is used as the supports and pozzolanic reaction is hindered by NaOH in WNCF sorbent. Furthermore, $CO_2$ desorption from the sorbents may be due to fly-ash. The interaction between fly-ash and $CO_2$ absorption components substantially attenuate the strength between captured $CO_2$ in CaO and NaOH.

Manufacturing of Artificial Lightweight Aggregates using a Coal Fly Ash Discharged from Fluidized Bed Combustor (유동층(流動層) 연소기(撚燒器)로 부터 발생(發生)된 석탄(石炭) 비산(飛散)재를 이용(利用)한 인공경량골재(人工輕量骨材) 제조(製造))

  • Kang, Min-A;Kang, Seung-Gu
    • 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.

A Study on Changes in Heavy Metal Contents in Concrete Prepared Using Coal Ashes (석탄재의 콘크리트 활용에 따른 중금속 함량변화 연구)

  • Lee, Jinwon;Choi, Seung-Hyun;Kim, Kangjoo;Kim, Seok-Hwi;Moon, Bo-Kyung
    • Economic and Environmental Geology
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    • v.51 no.4
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    • pp.371-379
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    • 2018
  • In many countries, recycling coal ashes as backfill materials for subsided lands, abandoned mine tunnels, and road pipeline constructions by making low-strength concretes with minimal amounts of cement is frequently considered for massive treatment of coal ashes. This study investigates the variation of heavy metals in the concrete test pieces prepared for the cases of using only Portland cement as binding material, fly ash as a replacement of the cement, sand as aggregates, and disposed ashes in the ash ponds as a replacement of aggregates. Heavy metal contents were measured based on the aqua regia extraction technique following the Korean Standard for Fair Testing of Soil Contamination and the influences of each materials on the total heavy metal contents were also assessed. Results show that the cement has the highest Cu, Pb, and Zn concentrations than any other materials. Therefore, the test pieces show significant concentration decreases for those metals when the cement was replaced by fly ash. Ponded ash shows low concentrations relative to fly ash in most of the parameters but shows higher Cu and Ni, and lower Pb levels than the sand aggregate. In overall, heavy metal levels of the test pieces are regulated by mixing among the used materials. Test pieces prepared during this study always show concentrations much lower than the Worrisome Level of Soil Contamination (Area 1), which was designated by the Soil Environment Conservation Act of Korea.

Evaluation of Some Rare Metals and Rare Earth Metals Contained in Coal Ash of Coal-fired Power Plants in Korea (국내 석탄화력발전소 석탄회 중 희유금속 가치 평가)

  • Park, Seok-Un;Kim, Jae-Kwan;Seo, Yeon-Seok;Hong, Jun-Seok;Lee, Hyoung-Beom;Lee, Hyun-Dong
    • Resources Recycling
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    • v.24 no.4
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    • pp.67-75
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    • 2015
  • The content distributions of some rare metals and rare earthe metals in coal ash (fly ash, bottom ash and pond ash) and leachate from coal-fired power plants were investigated. In case of Yttrium (Y) and Neodymium (Nd) which were strategic critical elements, their contents were ranged from about 23 ~ 75 mg/kg and it is shown they are worth to be developed for the recovery and separation method. Considering the annual amount of fly ash and bottom ash and pond ash, coal-fired power plants have great value of about 1,670 billion KRW and it is regards they are worthy as urban mines.

Leaching Property of Coal Fly Ash Using Water as the Solvent and Its Carbonation Performance (석탄 비산재의 물에 대한 침출 특성과 탄산화 성능에 관한 연구)

  • Shin, Jiyoon;Han, Sang-Jun;Wee, Jung-Ho
    • Journal of Korean Society of Environmental Engineers
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    • v.36 no.3
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    • pp.198-205
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    • 2014
  • The present paper investigates the leaching property of coal fly ash (FA) using distilled water as solvent and its performance of mineral carbonation. The highest leaching efficiency is obtained at 100 min after leaching begins and the overall leaching efficiencies of Ca and Na via five consecutive leachings were calculated to be 25.37% and 7.40%, respectively. In addition, because $Ca(OH)_2$ produced during the leaching reacts with $SiO_2$ which is the major component of FA, the Pozzolanic reaction may occur and thus reduces leaching efficiency. Total carbonation capacity of FA by absorbing $CO_2$ into FA leachates is 6.08 mg $CO_2/g$ FA and the contribution of alkali substances such as Ca, Na, Mg and K to this value is calculated to be 5.19 mg $CO_2/g$ FA. Carbonation efficiencies of Ca and Na based on leachates are 85.62% and 77.70%, respectively. On the other hand, the ratios of Ca and Na in raw FA to participate in carbonation are calculated to be 9.04% and 5.26%, respectively.