• Title, Summary, Keyword: solidification$CaCO_3$

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The Solidification of $CO_2$ by Using Waste Cement and Inorganic Waste By-Products (폐(廢)콘크리트 미분말(微粉末)과 무기성(無機性) 폐부산물(廢副産物)을 이용(利用)한 $CO_2$ 고형화(固形化))

  • Ahn, Ji-Whan;Yoo, Kwang-Suk
    • Journal of the Korean Institute of Resources Recycling
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    • v.18 no.3
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    • pp.3-10
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    • 2009
  • This paper will introduce the study which is the solidification and reduction of $CO_2$ green house gas, by using inorganic industrial wastes such like waste cement, steel making slag, incineration ash and so on. These inorganic wastes contain a large quantity of CaO content in common, which is easily reacted with CaO resulting in formation of $CaCO_3$. It will be suggested in this study that the necessary of the reduction and solidification of $CO_2$ gas with using industrial inorganic wastes is for building the Korea carbon storage model in this study.

Influence of Sulfur on the Inoculation Effect of Gray Cast Iron (회주철의 접종효과에 미치는 S의 영향)

  • Chung, Yae-Soo;Kim, In-Bae;Park, Ik-Min
    • Journal of Korea Foundry Society
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    • v.9 no.3
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    • pp.221-227
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    • 1989
  • The effect of sulfur content and inoculant on solidification microstructure and mechanical properties of gray cast iron have been investigated. The main results obtained are as follows, 1. In the FeSi3Ca1Ba inoculated irons, with the variation of sulfur content, low sulfur levels (${\sim}0.03%$) yield low chill depth, high tensile strength, good wear resistance and type A graphite with a pearlite matrix. High sulfur levels( >0.08%) provide high chill depth, low mechanical proper ties and type D graphite with small amount ferrite. 2. In case of inoculant variation with normal FeSi, FeSi3Ca1Ba, 30CaSi and uninoculation at 0.03%S level, lower chill depth and higher tensile strength was obtained in the order ; 30CaSi, FeSi3Ca1Ba normal FeSi, uninoculation.

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Solidification of Sandy Soils using Cementation Mechanism of Microbial Activity (미생물활성에 의한 시멘테이션 작용을 이용한 모래지반의 안정화)

  • Kim, Ki-Wook;Yun, Sung-Wook;Chung, Eu-Jin;Chung, Young-Ryun;Yu, Chan
    • Journal of The Korean Society of Agricultural Engineers
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    • v.56 no.6
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    • pp.169-176
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    • 2014
  • To evaluate bio-cementation of microbial on sands, laboratory test was conducted using acrylic cubic molding boxes ($5cm{\times}5cm{\times}5cm$). It was incubated the microbial, called Bacillus Pasteurii, according to Park et al (2011, 2012). and applied 50ml each specimen. Two type of sand samples used were Jumoonjin sand and common sand (well graded). These sands were molded in acrylic boxes with the relative density of 30 % and 60 % respectively. Microbial were poured onto the samples molded in acrylic boxes and cured at the room temperature and humidity. After 7, 14 and 21days, it was measured the compressive strength, pH, EC, and density and it were observed SEM and XRD to verify the effect of bio-cementation. It was found that bio-cementation was increased a strength of sands and it was appeared that strengths were related to the type of sand and relative density. Therefore it was confirmed the solidification of sands using the bio-cementation by microbial activation and the usefullness of acrylic molding boxes when tests were conducted on the soil of sands.

Enhancement of the Characteristics of Cement Matrix by the Accelerated Carbonation Reaction of Portlandite with Supercritical Carbon Dioxide

  • Kim, In-Tae;Kim, Hwan-Young;Park, Geun-Il;Yoo, Jae-Hyung;Kim, Joon-Hyung;Seo, Yong-Chil
    • Proceedings of the IEEK Conference
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    • pp.586-591
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    • 2001
  • This research investigated the feasibility of the accelerated carbonation of cement waste forms with carbon dioxide in a supercritical state. Hydraulic cement has been used as a main solidification matrix for the immobilization of radioactive and/or hazardous wastes. As a result of the hydration reaction for major compounds of portland cement, portlandite (Ca(OH)$_2$) is present in the hydrated cement waste form. The chemical durability of a cement form is expected to increase by converting portlandite to the less soluble calcite (CaCO$_3$). For a faster reaction of portlandite with carbon dioxide, SCCD (supercritical carbon dioxide) rather than gaseous $CO_2$, in ambient pressure is used. The cement forms fabricated with an addition of slated lime or Na-bentonite were cured under ambient conditions for 28days and then treated with SCCD in an autoclave maintained at 34$^{\circ}C$ and 80atm. After SCCD treatment, the physicochemical properties of cement matrices were analyzed to evaluate the effectiveness of accelerated carbonation reaction. Conversion of parts of portlandite to calcite by the carbonation reaction with SCCD was verified by XRD (X-ray diffraction) analysis and the composition of portlandite and calcite was estimated using thermogravimetric (TG) data. After SCCD treatment, tile cement density slightly increased by about 1.5% regardless of the SCCD treatment time. The leaching behavior of cement, tested in accordance with an ISO leach test method at 7$0^{\circ}C$ for over 300 days, showed a proportional relationship to the square root of the leaching time, so the major leaching mechanism of cement matrix was diffusion controlled. The cumulative fraction leached (CFL) of calcium decreased by more than 50% after SCCD treatment. It might be concluded that the enhancement of the characteristics of a cement matrix by an accelerated carbonation reaction with SCCD is possible to some extent.

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THE MICROSTRUCTURE OF Pb-DOPED SOLIDIFIED WASTE FORMS USING PORTLAND CEMENT AND CALCITE

  • Yoo, Hee-Chan;Lee, Dong-Jin
    • Environmental Engineering Research
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    • v.11 no.1
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    • pp.54-61
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    • 2006
  • An electron probe microanalysis (EPMA) investigation can provide quantitative and qualitative insight into the nature of the surface and bulk chemistry on solidified waste forms(SWF). The proportion of Pb in grain areas is below 0.3 wt. %, and the proportion near the border of the grain slightly increases to 0.98 wt. % but in the inter-particle areas farther from the grain, the concentration of Pb markedly increases. It is apparent that very little Pb diffuses into the tricalcium silicate($C_3S$) particles and most of the Pb exists as precipitates of sulfate, hydroxide, and carbonate in the cavity areas between $C_3S$ grains. Calcite additions on Pb-doped SWF are also observed to induce deeper incorporation of lead into the cement grains with EPMA line-analysis of cross-sections of cement grains. The line-analysis reveals the presence of $0.2{\sim}5$ weight % Pb over $5\;{\mu}m$ from cement grain boundaries. In the inter-particle areas, the ratio of Ca, Si, Al and S to Pb is relatively similar even at some distance from the grain border and the Pb (wt. %) ratio is reasonably constant throughout the whole inter-particles area. It is apparent that the enhanced development of C-S-H on addition of calcite can increasingly absorbs lead species within the silica matrix.