• Title, Summary, Keyword: Bentonite

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Evaluation of Amending Materials to Reduce Soil Loss from Sloping Remediated Agricultural Land (급경사 복원 농경지 토양 유실 저감을 위한 개량제 효율 및 현장 적용성 평가)

  • Hwang, Wonjae;Park, Minseok;Hyun, Seunghun;Ji, Won hyun;Lee, Sang-Hwan
    • Ecology and Resilient Infrastructure
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    • v.4 no.3
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    • pp.180-185
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    • 2017
  • Restoration of min-impacted arable land is often performed through stabilization of trace elements by amendment treatment combined with (clean) soil covering on the surface. Recently, soil loss problem from sloping remediated agricultural lands has risen as an emerging concern. In this study, efficacy of aggregation formation was assessed by single and binary treatments of four potential amendments (bentonite, lime, organic matter, and steel slag) applied on three cover soils having different clay contents (9.4, 14.7, and 21.2% for A, B, and C soils respectively). In results of single treatments, 5% organic matter for A soil and 5% lime for B and C soils were found most effective for the aggregation formation compared to the respective controls (without amendments). Among nine binary treatments, 3% organic matter + 1% lime for A soil and 1% organic matter + 3% lime for both B and C soils led to the highest formation of aggregation (30.4, 25.0, and 36.5% for A, B, and C soils). For a site-application, the soil erodibility difference between the cover soils (0.045, 0.051, and 0.054 for A, B, and C soils, respectively) and the national average of arable land (0.032) was assumed to be compensated by amendment addition, which is equivalent to 29.1% aggregation formation. To achieve the aggregation goal, 5% lime for A and B soils and 3% lime for C soil were best in the consideration of benefit/cost, thereby effectively and economically reducing soil loss from sloping remediation site. Soil alkalinity induced by lime treatment was not considered in this work.

Simulation-Based Design of Shear Mixer for Improving Mixing Performance (혼합효율 개선을 위한 Shear Mixer의 시뮬레이션 기반 형상 설계)

  • Kim, Tae-Young;Jeon, Gyu-Mok;Ock, Dae-Kyung;Park, Jong-Chun
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.20 no.2
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    • pp.107-116
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    • 2017
  • When drilling operation is being performed, many physical and chemical changes are occurred near wellbore. To handle various changes of well condition and keep drilling process safe, additives of bulk, such as bentonite for increasing density of drilling mud, barite for increasing viscosity of drilling mud, polymer for chemical control, or surfactant, are added into drilling mud through a mud shear mixer. Because the achievement of the required material property through mud mixing system is essential to stabilize drilling system, it is of importance to analyze multi-phase flow during mud mixing process, which is directly related to increase mixing performance of the system and guarantee the safety of the whole drilling system. In this study, a series of liquid-solid flow simulation based on a computational fluid dynamics (CFD) are performed with comparing to solid concentration in experiment by Gilles et al. [2004] to understand the characteristics of liquid-solid mixing in a mud shear mixer. And then, the simulation-based design of shear mixer are carried out to improve mixing performance in a mud handling system.

Mineralogical Properties and Paragenesis of H-smectite (H-스멕타이트의 광물학적 특성과 생성관계)

  • Noh, Jin-Hwan;Hong, Jin-Sung
    • Journal of the Mineralogical Society of Korea
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    • v.23 no.4
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    • pp.377-393
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    • 2010
  • Pumiceous tuffs occurring in the Beomgockri Group are examined applied-mineralogical characteristics and their controling factors to evaluate their potentials as the adsorption-functional mineral resources. The pumiceous tuffs are diagenetically altered to low-grade zeolitcs and bentonites in the Janggi area. Compositional specialty due to the presence of pumice fragments induces the altered tuffs to exhibit the characteristic adsorption property combined with cation exchange capacity, specific surface area, and acidic pH. Unusual lower pH in the adsorption-functional mineral substances is turned out to be originated from the presence of H-smectite having $H^+$ in the interlayer site of the sheet structure. On account of disordered crystallinity resulting from the exchanged $H^+$ in the interlayer site, the smectite commonly forms crenulated edges in the planar crystal form and exhibits characteristic X-ray diffraction patterns showing comparatively lower intensities of basal spacings including (001) peak than conventional Ca-smectite. Based on the interpretation of paragenetic relations and precursor of the H-smectite, a genetic model of the peculiar clay mineral was proposed. The smectite formation may be facilitated resulting from the precipitation of opal-CT at decreasing pH condition caused by the release of H+ during diagenetic alteration of pumice fragments. Because of the acidic smectite, the low-grade mineral resources from the Beomgockri Group may be applicable to the adsorption industry as the raw materials of acid clays and bed-soil.

Roles and Importance of Microbes in the Radioactive Waste Disposal (방사성폐기물 처분에서 미생물의 역할과 중요성)

  • Baik, Min-Hoon;Lee, Seung-Yeop;Roh, Yeol
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.7 no.1
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    • pp.63-72
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    • 2009
  • Recently the importance and interest for the microbes has been increased because several important results for the effects of microbes on the radioactive waste disposal have been published continuously. In this study, research status and major results on the various roles and effects of microbes in the radioactive waste disposal have been investigated. We investigated and summarized the roles and major results of microbes in a multi-barrier system consisting of an engineered barrier and a natural barrier which is considered in radioactive waste disposal systems. For the engineered barrier, we discussed about the effects of microbes on the corrosion of a waste container and investigated the survival possibility and roles of microbes in a compacted bentonite buffer. For the natural barrier, the roles of microbes present in groundwaters and rocks were discussed and summarized with major results from natural analogue studies. Furthermore, we investigated and summarized the roles and various interactions processes of microbes and their effects on the radionuclide migration and retardation including recent research status. Therefore, it is expected that the effects and roles of microbes on the radioactive waste disposal can be rigorously evaluated if further researches are carried out for a long-term behavior of the disposal system in the deep geological environments and for the effects of microbes on the radionuclide migration through geological media.

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The State of the Technology: Application of Cementitious Materials to Deep Repository Tunnels for Radioactive Waste Disposal (방사성폐기물의 심지층 처분터널에서의 시멘트 물질 적용에 관한 기술현황)

  • Kim, Jin-Seop;Kwon, Sang-Ki;Cho, Won-Jin;Cho, Gye-Chun
    • Tunnel and Underground Space
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    • v.19 no.5
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    • pp.373-387
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    • 2009
  • Considering the current construction technology and research status of deep repository tunnels for radioactive waste disposal, it is inevitable to use cementitious materials in spite of serious concern about their long-term environmental stability. Thus, it is an emerging task to develop low pH cementitious materials. This study reviews the state of the technology on low pH cements developed in Sweden, Switzerland, France, and Japan as well as in Finland which is constructing a real deep repository site for high-level radioactive waste disposal. Considering the physical and chemical stability of bentonite which acts as a buffer material, a low pH cement limits to $pH{\leq}11$ and pozzolan-type admixtures are used to lower the pH of cement. To attain this pH requirement, silica fume, which is one of the most promising admixtures, should occupy at least 40 wt% of total dry materials in cement and the Ca/Si ratio should be maintained below 0.8 in cement. Additionally, selective super-plasticizer needs to be used because a high amount of water is demanded from the use of a large amount of silica fume.

Brewing and Quality Characteristics of Korean Honey Wine (Mead) with a Variety of Honey and Yeast (다양한 벌꿀과 효모를 이용한 벌꿀와인의 제조 및 품질 특성)

  • Lee, Dae Hyoung;Kang, Heui-Yun;Lee, Yongseon;Cho, Chang-Hui;Park, In-Tae;Kim, Heui-Dong;Lim, Jae-Wook
    • Korean Journal of Food Science and Technology
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    • v.44 no.6
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    • pp.736-742
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    • 2012
  • In this study, the brewing and quality characteristics of a variety of honey and yeast strains in Korea were investigated. After fermenting acacia honey, chestnut honey, citrus honey, and mixed flower honey using commercial yeast, the quality changes during fermentation were investigated. Chestnut honey wine (mead) and mixed flower mead showed the highest ethanol contents of 11.9 and 11.3%, respectively after fermenting for 8 days at $25^{\circ}C$. Acacia mead and citron (Chinese lemon) mead showed 5.0 and 8.2% ethanol contents, respectively. Mixed mead, which fermented with acacia honey and mixed flower honey, in order to advance sensory properties, showed the best sensory properties, generating 10.9% ethanol, while another product with citron honey and mixed flower honey generated 11.1% of ethanol but with a lower sensory value. When adding corium peels to the mixed mead of acacia honey and mixed flower honey, the ethanol content was not increased by addition of corium peels into mixed mead, but its total acceptability was increased by addition of 2% corium peels. To check the mead clarification, it was treated with 0.6% of bentonite and filtered; then, its turbidity was observed over a storage period. The safe result for precipitation was shown at the condition of storing at $10^{\circ}C$ for 15 days with 0.24 NTU (Nepthelometric Turbidity Unit).

Evaluation of Ground Thermal Conductivity by Performing In-Situ Thermal Response test (TRT) and CFD Back-Analysis (현장 열응답 시험(TRT)과 CFD 역해석을 통한 지반의 열전도도 평가)

  • Park, Moonseo;Lee, Chulho;Park, Sangwoo;Sohn, Byonghu;Choi, Hangseok
    • Journal of the Korean Geotechnical Society
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    • v.28 no.12
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    • pp.5-15
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    • 2012
  • In this study, a series of CFD (Computational Fluid Dynamics) numerical analyses were performed in order to evaluate the thermal performance of six full-scale closed-loop vertical ground heat exchangers constructed in a test bed located in Wonju. The circulation HDPE pipe, borehole and surrounding ground formation were modeled using FLUENT, a finite-volume method (FVM) program, for analyzing the heat transfer process of the system. Two user-defined functions (UDFs) accounting for the difference in the temperatures of the circulating inflow and outflow fluid and the variation of the surrounding ground temperature with depth were adopted in the FLUENT model. The relevant thermal properties of materials measured in laboratory were used in the numerical analyses to compare the thermal efficiency of various types of the heat exchangers installed in the test bed. The simulation results provide a verification for the in-situ thermal response test (TRT) data. The CFD numerical back-analysis with the ground thermal conductivity of 4 W/mK yielded better agreement with the in-situ thermal response tests than with the ground thermal conductivity of 3 W/mK.

Evaluation of Hydraulic Conductivity of Slurry-wall-type Vertical Cutoff Wall with Consideration of Filter Cake (필터케이크(filter cake)를 고려한 슬러리월 연직차수벽의 현장투수계수 평가)

  • Nguyen, The Bao;Lee, Chul-Ho;Choi, Hang-Seok;Kim, Sang-Gyun
    • Journal of the Korean Geotechnical Society
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    • v.24 no.11
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    • pp.121-131
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    • 2008
  • In constructing a slurry trench cutoff wall, bentonite-water slurry is used to secure the stability of sidewalls during excavation before the wall is completed by backfilling. Unexpectedly, a thin but relatively impermeable layer called filter cake can be formed on the excavation surface, which significantly influences the result of slug test analysis in the cutoff wall if not considered. This study is to examine the effect of filter cake on evaluating hydraulic conductivity of the vertical cutoff wall through slug test analysis with the aid of the verified numerical program Slug_3D. The no-flux boundary conditions were adopted in Slug_3D to simulate the filter cake on the interface between the wall and the natural soil. A new set of type curves were built for applying the type curve method. New modification factors were obtained for using the modified line-fitting method. With consideration of filter cake, the type curve method and the modified line-fitting method were adopted to reanalyze the case study taken from EMCON (1995). The previous results achieved by Choi and Daniel (2006) without consideration of filter cake were compared with the present results obtained in this paper. The comparison emphasizes the necessity of considering filter cake when analyzing slug test results in vertical cutoff walls.

Analysis of the Thermal and Structural Stability for the CANDU Spent Fuel Disposal Canister (CANDU 처분용기의 열적-구조적 안정성 평가)

  • Lee, Jong-Youl;Cho, Dong-Geun;Kim, Seong-Gi;Choi, Heui-Joo;Lee, Yang
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.6 no.3
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    • pp.217-224
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    • 2008
  • In deep geological disposal system, the integrity of a disposal canister having spent fuels is very important factor to assure the safety of the repository system. This disposal canister is one element of the engineered barriers to isolate and to delay the radioactivity release from human beings and the environment for a long time so that the toxicity does not affect the environment. The main requirement in designing the deep geological disposal system is to keep the buffer temperature below 100$^{\circ}C$ by the decay heat from the spent fuels in the canister in order to maintain the integrity of the buffer material. Also, the disposal canister can endure the hydraulic pressure in the depth of 500 m and the swelling pressure of the bentonite as a buffer. In this study, new concept of the disposal canister for the CANDU spent fuels which were considered to be disposed without any treatment was developed and the thermal stability and the structural integrity of the canister were analysed. The result of the thermal analysis showed that the temperature of the buffer was 88.9$^{\circ}C$ when 37 years have passed after emplacement of the canister and the spacings of the disposal tunnel and the deposition holes were 40 m and 3 m, respectively. In the case of structural analysis, the result showed that the safety factors of the normal and the extreme environment were 2.9 and 1.33, respectively. So, these results reveal that the canister meets the thermal and the structural requirements in the deep geological disposal system.

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Hygroscopic Characteristic of Hydrothermal reacted Panels using Porous Materials (다공성 원료와 수열합성으로 제조한 건축 내장용 패널의 흡방습 특성)

  • Kwon, Choon-Woo;Chu, Yong-Sik;Song, Hun;Lee, Jong-Kyu
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.705-708
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    • 2008
  • Diatomite, bentonite and zeolite were used as porous materials for fabricating hygroscopic panels. Moisture adsorption and desorption of porous materials were investigated and hydrothermal method was applied to fabricate panels. Cheolwon diatomite and Pohang zeolite showed excellent characteristics of moisture adsorption and desorption. These characteristics were caused by higher surface area and pore volume of porous materials. Moisture adsorption contents were influenced by surface area and pore volume of panels, and surface area more effected on moisture adsorption. Moisture adsorption content of panel with 10% Pohang zeolite was 180g/m$^2$and that of 10% Cheolwon diatomite was 170g/m$^2$. Moisture desorption content of panel with 10% Pohang zeolite was 105g/m$^2$. Moisture adsorption contents of panel with porous materials were higher than that of panel without porous materials.

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