• Title/Summary/Keyword: Limestone

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MICRSTRUCTURAL INVESTIGATION OF CALCINED AND SULFATED LIMESTONE FOR THE UTILIZAION IN THE AFBC ENVIRONMENT

  • Kim, Hyung-Taek;Kim, Dong-Hyung;Kim, Hong-Tae;Hyukbo Kwon
    • Journal of the Korean institute of surface engineering
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    • v.26 no.5
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    • pp.255-262
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    • 1993
  • Major parameters determining the extent of Ca utilization were investigated for their calcination/sulfation behavior of limestone in the AFBC(Atmospheric Fluidized Bed Combustion) environments. Three different particle sizes of Fredonia limestone were investigated in the lab-scale tubular reactor. The results of the calcination codnversion of limestone imply that thesd decomposition rate of CaCO3 into CaO is dependent on the amount of heat which limestone absorbed. Hg porosimeter measurement of calcined limestone illustrated that surface area and pore volume are increased with decreasing particle size. Raw Fredonia limestone and sequentially as well as simultaneously calcined/sulfated limestones were also examined using SEM. The SEM Studied showed that the surface of the calcined limestone particles is more diffusive nature than that of the parent calcite. However, the sulfur distribution pattern of simultaneously-treated particles and that of the se-quentially-treated one shows no difference.

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The Stratigraphy and Geologic Structure of the Great Limestone Series in South Korea (남한(南韓) 대석회암통(大石灰岩統)의 층서(層序)와 지질구조(地質構造))

  • Kim, Ok Joon;Lee, Ha Young;Lee, Dai Sung;Yun, Suckew
    • Economic and Environmental Geology
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    • v.6 no.2
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    • pp.81-114
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    • 1973
  • The purpose of the present study is to clarify the stratigraphy and geologic structure of the Great Limestone Series by means of study on fossil conodonts and detail investigation of geologic structure. In recent years very few geologists in Korea argue without confident evidences against the age and stratigraphy of the Great Limestone Series which have been rather well established previously in most parts of the regions although it is ambiguous and has not been studied in other areas. Five type localities in the Kangweon basin where the Great Limestone Series is well cropped out were chosen for the study. Total 26 genus and 66 species of conodont were identified from 290 samples collected and treated. From the study on conodonts the age of each formations of the Great Limestone Series has been determined as follows: The Great Limestone Series of Duwibong type Duwibong limestone: Caradocian (mid-Ord.) Jikunsan shale: Landeilian (mid-Ord.) Maggol limestone: Llanvirn-Llandeilian (mid-Ord.) Dumugol: Arenigian (Ord.) Hwajeol: Upper Cambrian The Great Limestone Series of Yeongweol type Mungok (Samtaesan) : Ordovician Machari: upper Cambrian The Great Limestone Series of Jeongseon type Erstwhile Jeongseon limestone: mid-Ord. The erstwhile Jongseon Limestone formation in Jeongseon district is separated into Hwajeol, Dongjeom, Dumudong, and Maggol formations which were cropped out repeatedly by folding and faulting, but Maggol is predominant in areal distribution. Yemi Limestone Breccia bed is not a single bed but distributed in several horizons so that it bears no stratigraphic significance. The limestone bed above Yemi Limestone Breccia, which was believed by some geologists to be much younger than Ordovician, is identified to be Maggol and its age is determined to be mid-Ordovician. Sambangsan formation in Yeongweol district was believed to be Cambrian age and lower horizon than Machari formation by Kobayashi, but C. M. Son believed that it might belong to later than Ordovician and lies above the Great Limestone Series of Yeongweol type. It was identified to be upper Cambrian and lies beneath the Machari formation and above the Daeki formation, the lower most horizon of the Great Limestone Series. The age of Yeongweol type Choseon system is contemporaneous with that of Duwibong type Choseon system. The difference in lithofacies is not due to lateral facies change, but due to the difference in its depositional environment. The Yeongweol type Choseon system is believed to be deposited in the small Yeongweol basin which was separated from the main Kangweon sedimentary basin. Judging from these facts it is definitely concluded that there exists no Gotlandian formation in the regions studied. Structurally the Kangweon basin comprises five basins and two uplifted areas. These structures were originated by at least two crustal movements, that is, Songrim disturbance of Triassic and Daebo orogeny of Jurasic age.

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Characteristics of Limestone Regeneration in the wet Limestone FGD Process (습식 석회석 배연 탈황 공정에서의 석회석 재생 특성)

  • 손종렬;문경환;모세영
    • Journal of Environmental Health Sciences
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    • v.27 no.4
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    • pp.9-14
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    • 2001
  • This study was performed to develop the modified FGD(Flue Gas Desulfurization) process which can eliminate the possibility of generating secondary pollutants. Limestone was regenerated by adding ammonium hydroxide and carbon dioxide, and reusing it as a absorbent in FGD gypsum Process. A series of the new or modified FGD process which include desulfurization and regeneration limestone from CaSO$_3$. 1/2H20 and CaSO4 . 2H2O, were carried out under various experimental conditions. The results showed that the optimum injection ratio for regeneration of limestone was 0.3 ml/min of CO2 flow rate, 2 ml of NH4OH per 0.01 M of regent grade CaSO4 . 2H20O and the optimum regeneration temperature was 50. The increaser was the number of times of limestone regeneration, the faster was the breakthrough point of desulfurization at the desulfurination process which the regenerated limestone was used. Then the efficiency of desulrurization was decreased. This study can be confirmed the possibility for reuse of regenerated limestone due to the similarity of desulfurization characteries both reagent grade calcium carbonate and regenerated calcium carbonate. Finally, it appeared that the new technology using regenerated 1imestone can be applied to the FGD process.

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Mineral Phase and Microstructure Behaviors on Burning Condition of Domestic Low-grade Limestone (국내 저품위 석회석의 소성조건에 따른 광물상 및 미세구조 거동)

  • Cho, Jin Sang;Moon, Ki-Yeon;Choi, Moon-Kwan;Cho, Kye-Hong;Ahn, Ji-Whan;Yeon, Kyu-Seok
    • Journal of the Korean Ceramic Society
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    • v.51 no.2
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    • pp.88-96
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    • 2014
  • Natural hydraulic lime (NHL) is produced by burning a form of low-grade limestone containing silica and alumina which, above certain temperatures, combine with calcium oxide. The resulting silicates and aluminates impart hydraulic properties to the product. This study aims to determine the calcined characteristics of NHL using domestic low-grade limestone with maximized hydraulic properties. Six types of low-grade limestone containing $SiO_2$ were selected and experiments were carried out with different burning temperatures and holding times. The burning temperature and holding time as the most suitable burning conditions were $1,200^{\circ}C$ to $1,300^{\circ}C$ and 3 to 7 h, respectively, for the manufacturing of NHL from domestic low-grade limestone. These results demonstrate the feasibility of NHL using domestic low-grade limestone to produce NHL.

Mechanical Properties and Durability of Concrete in Relation to the Amount of Limestone Use (석회석 혼입량에 따른 콘크리트의 역학적 및 내구특성)

  • Oh, Sungwoo;Shin, Dongcheol
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.21 no.3
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    • pp.138-144
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    • 2017
  • In order to reduce carbon dioxide emission in construction industry, less amount of cement use can be one of the alternatives to manufacture concrete. One of the non-sintered construction materials are limestone, which is the raw material to manufacture ordinary Portland cement(OPC). A large amount of limestone have already been used as binders such as blended cement in Europe and US. Even European countries were already established the standard of blended cement, where the limestone can be used up to 35 percent. In this study, experimental researches were conducted to investigate the effects of limestone replacement on the mechanical properties and durability of concrete with 15%, 25% and 35% of limestone substitution to use limestone in blended cement. 15 percent use of limestone in blended cement developed equivalent or even higher compressive strengths compared to Plain mixture. Porosity of limestone cement with 15 percent substitution was much lower than Plain mixture. Most durability tests such as concrete carbonation, freeze-thaw cycle and drying shrinkage strains were conducted to evaluate long-term performance, and the test results indicated that 15 percent of limestone use did not significantly influence on the concrete durability compared with plain concrete.

Influence of Limestone Powder on the Hydration of slag cement (슬래그 시메\ulcorner의 수화반응에 미치는 석회석 분말의 영향)

  • 이민석;윤철현;최현국
    • Proceedings of the Korea Concrete Institute Conference
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    • 1999.10a
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    • pp.85-88
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    • 1999
  • We tested the limestone powder as a filler powder for the effective use of slag cement. Hydration process were investigated by measuring the thermal differential analysis(DTA), compressive strength, XRD patterns, calorimeter of slag cement-limestone powder paste prepared by mixing limestone powder-slag cement. The results obtained in this study, there were no significant difference between the cases of adding up to 5% limestone powder, but the reaction time was accelerated. Also the compressive strength was increased for adding up to 5% limestone powder. The min hydrated paste products were Ca(OH)2 and calcium silicate hydrates. In the case of mixed limestone powder peak appear tricalcium carboaluminate hydrate in the sample of 7 days hydration.

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Sulfate Resistance of Cement Matrix Containing Limestone Powder

  • Moon Han-Young;Jung Ho-Seop;Lee Seung-Tae;Kim Jong-Pil
    • Journal of the Korea Concrete Institute
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    • v.16 no.3 s.81
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    • pp.433-440
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    • 2004
  • In order to improve the performance of concrete, generally, modern cements often incorporate several mineral admixtures. In this study, the experimental included the flow value, air content of mortar containing limestone powder and length change and compressive strength of mortar specimen immersed in sulfate solutions. From the experimental results, the limestone powder cement matrices improved the physical properties and sulfate resistance of cement matrices at $10\%$ replacement ratio of limestone powder. The $30\%$ replacement ratio of limestone powder was significantly deteriorated in sodium sulfate solution. Irrespective of fineness levels of limestone powder, length change and SDF of mortar specimens with only $10\%$ replacement was much superior to the other replacements.

XRD Analysis of Portland Limestone Cement Paste (포틀랜드 석회석 시멘트에 관한 XRD 분석)

  • Bang, Mi-Jin;Shin, Ki-Su;Park, Ki-Bong
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2018.05a
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    • pp.189-190
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    • 2018
  • This study produced Portland limestone cement at the rate of limestone substitution by grinding limestone and clinker together, and it conducted an XRD analysis to determine the sign language response structure as a basic study on Portland Limestone Cement. As a result of the XRD analysis, the higher the substitution rate of limestone, the more likely it is that the detection rate of ettringite is decreased. Additionally, we could see that the production volume of Mono-carbonate was increasing.

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Desulfurization kinetics of waste paper-sludge and limestone in a fluidized bed reactor (유동층반응기에서 폐제지슬러지와 석회석의 탈황 동역학)

  • 조상원;오광중
    • Journal of Environmental Science International
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    • v.11 no.10
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    • pp.1089-1096
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    • 2002
  • The objectives of this study were to investigate the desulfurization kinetics of paper sludge and limestone in a fluidized bed reactor according to bed temperature and air velocity. The experimental results were presented as follows ; First, the bed temperature had a great influence on the desulfurization efficiency of limestone and paper sludge. In paper sludge, the optimum condition in desulfurization temperature was at 80$0^{\circ}C$ and in limestone, that was at 850 $^{\circ}C$ or 900 $^{\circ}C$ Second, as air velocity increased, the desulfurization efficiency(or the absorbed amount of sulfur dioxide) by limestone and paper sludge decreased. And the absorbed amount of sulfur dioxide by paper sludge was larger than that of by limestone. Third, as the velocity increased and the optimum desulfurization temperature became, ks and the removal efficiency increased. So, ks, kd highly depended on the air velocity and bed temperature.

Setting and Hydration Heat Development Characteristics with Binder Types (결합재 종류에 따른 응결과 수화발열 특성)

  • 박찬규;이승훈;하재담
    • Proceedings of the Korea Concrete Institute Conference
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    • 2002.10a
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    • pp.369-374
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    • 2002
  • In this paper, setting and hydration heat development characteristics with three binder types, type IV cement+fly ash, type IV cement+slag powder and type IV cement + limestone powder. were investigate. As results, it was shown that the limestone powder decreased the initial setting time regardless of replacement ratio, especially the range of 20~50% replacement ratio, and the 2nd peak was shifted ahead when the limestone powder replacement ratio increased. But for the f1y ash and the limestone powder, contrary results were obtained compared with the limestone powder.

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