• Title/Summary/Keyword: Kaolin

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Effect of Fluorides on Mullitization of $SiO_2-Al_2O_3$ System; Korean Kaolin (플루오르화물이 $SiO_2-Al_2O_3$계 원료의 물라이트화에 미치는 영향)

  • 최상욱;이철규
    • Journal of the Korean Ceramic Society
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    • v.17 no.2
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    • pp.61-68
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    • 1980
  • The effect of the addition of various fluoreides on the mullitization of Korean crude kaolin was studied by X-ray powder diffraction and scanning electron microscopic methods. Kaolin without any addition of fluoreides began to be transformed into the mullite at 1, 10$0^{\circ}C$. Mullite peaks were discernible in the X-ray diffraction patterns of the specimens which contained fluorides equivalent to about 2 wt % fluorine, and which were sintered at 1, 05$0^{\circ}C$. The higher the concentration of fluorine in kaolin, the lower was the initiatinig temperature of mullitization. Experiments , for example, showed that mullite could be formed at 95$0^{\circ}C$ from kaolin mixed with 3.4% fluorine. Of the fluoride, addtives, sodiumsiliconfluoride $(Na_2SiF_6)$ was must effective in mullite formation of kaolin. In order of accelerating mullitization, the fluorides except $Na_2SiF_6$ could be placed in following sequence ; (1) sodium (NaF) (2) aluminium$(AlF_3)$ (3)potassium(KF) (4) ammonium$(NH_4F)$ (5) magnesium$(MgF_2)$ (6) calcium$(CaF_2)$. It was considered that the intrinsic characteristics of fluorides, such as size of ionic radiu, charge , bond strength between cation and anion, and electronegativity of cation affected millitization of halloysite, a main constituent mineral of kaolin.

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Ageing effect on compressibility, permeability and shear strength of clayey soils exposed to salt solutions

  • Cakar, Emel;Yukselen-Aksoy, Yeliz
    • Geomechanics and Engineering
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    • v.25 no.3
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    • pp.245-251
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    • 2021
  • The present study investigated the ageing effect on compressibility, permeability and shear strength behavior of kaolin and bentonite samples in the presence of NaCl and CaCl2 solutions. The compressibility, permeability and shear strength parameters were determined on the 60, 190, and 250 days cured samples. The results have shown that, the kaolin sample becomes more compressible in the presence Ca2+ ions with ageing. Generally, the normalized compression index values of bentonite samples increased at the end of 60 days and 250 days curing time periods. The normalized permeability value of kaolin decreased by ageing in the presence of Na+ ions almost twofold. The permeability values of bentonite increased both in NaCl and CaCl2 solutions during ageing. In the presence of Na+ ions kaolin had higher max. shear stress value than Ca2+ ions. When the max. shear stress values of 0, 60 and 190 days samples were compared, it was seen that NaCl solution had no significant effect on the shear strength of kaolin sample. However, the shear strength of kaolin increased in the CaCl2 solution during ageing. In the presence of Ca2+ ions the max. shear stress value of bentonite was higher. The results of this study have shown that ageing has significant effects on the compressibility, permeability and shear strength of kaolinitic and bentonitic clayey soils.

The Effect of Meta-Kaolin Replacement on Alkali-Silica Reaction (메타카올린 치환에 따른 알칼리-실리카 반응 팽창 저감효과)

  • Jun Ssang Sun;Lee Hyomin;Jin Chi Sub;Hwang Jin Yeon
    • Proceedings of the Korea Concrete Institute Conference
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    • 2004.05a
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    • pp.360-363
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    • 2004
  • The effectiveness of Meta-Kaolin to prevent detrimental expansion due to alkali-silica reaction was investigated through the ASTM C 1260 method. Reactive aggregate used is a metamorphic rock. The replacement proportions of portland cement by Meta-Kaolin were 0, 5, 10, 15, 25 and 35 percent, respectively. The results indicate that 25 percent replacement of portland cement by Meta-Kaolin seems to be most effective to reduce alkali-silica reaction expansion under this experimental conditions.

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Synthesis of Mullite from Kaolin by Seed Addition Method (Kaolin으로부터 Seed 첨가법에 의한 Mullite 합성)

  • 김인섭;박주석;이명웅;이병하;소유영
    • Journal of the Korean Ceramic Society
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    • v.35 no.8
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    • pp.878-884
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    • 1998
  • Synthesis of high purity mullite from korean resourceful kaolin and water-soluble aluminium salts was in-vestigated by addition of mullite seed. Single phase of mullite was formed at 1350$^{\circ}C$ however its mullite con-tent was 31-33% Maximum content of mullite synthesized from kaoin aluminium nitrate and 8wt% mul-lite seed was 98% at 1600$^{\circ}C$ for 4 hours.

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Experimental & computational study on fly ash and kaolin based synthetic lightweight aggregate

  • Ipek, Suleyman;Mermerdas, Kasim
    • Computers and Concrete
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    • v.26 no.4
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    • pp.327-342
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    • 2020
  • The objective of this study is to manufacture environmentally-friendly synthetic lightweight aggregates that may be used in the structural lightweight concrete production. The cold-bonding pelletization process has been used in the agglomeration of the pozzolanic materials to achieve these synthetic lightweight aggregates. In this context, it was aimed to recycle the waste fly ash by employing it in the manufacturing process as the major cementitious component. According to the well-known facts reported in the literature, it is stated that the main disadvantage of the synthetic lightweight aggregate produced by applying the cold-bonding pelletization technique to the pozzolanic materials is that it has a lower strength in comparison with the natural aggregate. Therefore, in this study, the metakaolin made of high purity kaolin and calcined kaolin obtained from impure kaolin have been employed at particular contents in the synthetic lightweight aggregate manufacturing as a cementitious material to enhance the particle crushing strength. Additionally, to propose a curing condition for practical attempts, different curing conditions were designated and their influences on the characteristics of the synthetic lightweight aggregates were investigated. Three substantial features of the aggregates, specific gravity, water absorption capacity, and particle crushing strength, were measured at the end of 28-day adopted curing conditions. Observed that the incorporation of thermally treated kaolin significantly influenced the crushing strength and water absorption of the aggregates. The statistical evaluation indicated that the investigated properties of the synthetic lightweight aggregate were affected by the thermally treated kaolin content more than the kaoline type and curing regime. Utilizing the thermally treated kaolin in the synthetic aggregate manufacturing lead to a more than 40% increase in the crushing strength of the pellets in all curing regimes. Moreover, two numerical formulations having high estimation capacity have been developed to predict the crushing strength of such types of aggregates by using soft-computing techniques: gene expression programming and artificial neural networks. The R-squared values, indicating the estimation performance of the models, of approximately 0.97 and 0.98 were achieved for the numerical formulations generated by using gene expression programming and artificial neural networks techniques, respectively.

Studies on Surface Treatment of Kaolin Filler (Part 3) - Interaction between Surface Modified Filler and Rubber Matrix and Characterization of Reinforcement Effects of Filler - (Kaolin충전제(充塡劑) 표면처리(表面處理)에 관(關)한 硏究(연구) (제3보(第3報)) - 첨가(添加)된 충전제充塡劑)와 고무Matrix와의 Interaction 및 충전제(充塡劑) 보강효과(補强效果)의 특성화(特性化) -)

  • Kwon, Dong-Yong;Hong, Sung-Il
    • Elastomers and Composites
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    • v.20 no.1
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    • pp.25-39
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    • 1985
  • Elastomer-filler interaction in terms of characterization of filler effects was studied using natural rubber(NR) loaded with kaolin fillers modified with sodium polyphosphate and poly(maleic anhydride), respectively. Kaolins modified with sodium polyphosphate or poly(maleic anhydride) show adhering characteristics by Kraus plot. Reinforcement activity according to Cunneen-Russell method is given by those fillers, in which sodium polyphosphate-treated kaolin presents more favorable results than that treated with poly(maleic anhydride) with respect to adhesion constant, reinforcement extent, elastic constant, and crosslink density. When applied to Blanchard's linkage reinforcement theory, NR vulcanizates loaded with kaolin modified with sodium polyphosphate meet the requirements for both approximate linkage reinforcement(${\psi}'$) of 1.02 to 4.94 and accurate linkage reinforcement($\psi$) of 1.00 to 1.18, representing the values of effective wetting($C_{\psi}$) for 0.001 to 0.029 and intrinsic linkage reinforcement(${\psi}_0$) for 1.015 to 1.124, respectively, whille negligible linkage reinforcement is shown by NR vulcanizates loaded with kaolin treated with poly(maleic anhydride). Dynamic storage modulus(G') given by surface modified kaolins presents more favorable crosslink density rates of $2.260{\times}10^{-5}\;mole/cm^3-min$. for sodium polyphosphate treated kaolin and $1.305{\times}10^{-5}\;mole/cm^3-min$. for poly(maleic anhydride) treated kaolin, respectively, compared to untreated kaolin showing the rate of $1.033{\times}10^{-5}\;mole/cm^3-min$.

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Permeation Characteristics of the Submerged Membrane Module Using the Rotating Disks (회전원판을 이용한 침지형 분리막 모듈의 투과특성)

  • Chung Kun-Yong;Cho Young-Su;Kim Jong-Pyo
    • Membrane Journal
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    • v.16 no.1
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    • pp.51-58
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    • 2006
  • The permeation experiments were carried out for the submerged membrane module equipped with self-designed rotating disks in order to determine the effect of fouling reduction and the optimum operating conditions as a function of operating time. Kaolin and bentonite particles were used to prepare various concentrations of feed solution. Every experiment was continued until 60 minutes at various rotating disk speeds up to 120 rpm. The suction pressure for kaolin solutions decreased to 28% by using rotating disk to decrease the fouling. Also, the optimum permeation flux decreased as kaolin concentration increased, and became 60 to 70 LMH for 0.4 wt% of kaolin solution. The suction pressure for bentonite experiment approached to 0 mmHg at 30 LMH and above 80 rpm rotating disk speed.

Permeation behavior of kaolin solution in dead-end microfiltration (카올린 용액의 Dead-end형 정밀여과투과)

  • 장규만;정건용
    • Proceedings of the Membrane Society of Korea Conference
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    • 1998.10a
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    • pp.133-136
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    • 1998
  • 0.1 내지 $4 \mum$의 입도분포를 가진 kaolin용액을 dead-end형 여과 장치(Amicon Cell, 8050)를 이용하여 공칭세공이 $0.2 \mum$인 PTFE막으로 농도 및 운전압력에 따른 투과실험을 하였다. Kaolin 용액의 투과유속은 케이크 저항이 지배적이었으며 초기에는 분리막 표면에 케이크가 형성되고 그 후에 분리막 세공의 오염이 발생하는 것으로 관찰되었다.

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Effect of $Al_2O_3$ as Additives on the Sintering of Sic-Clay-Kaolin Chomotte System (탄화규소-점토-Kaolin Chamotte 계의 소결에 미치는 첨가제 $Al_2O_3$의 영향)

  • 백용혁;박종훈
    • Journal of the Korean Ceramic Society
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    • v.18 no.1
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    • pp.41-47
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    • 1981
  • The sintering characteristics of the SiC-Clay-Kaolin chamotte system were studied by addition of $Al_2O_3$ for the manufacture of silicate-bonded silicon carbide refractories at $1350^{\circ}C$. The sinterbilit of SiC-Binder mixture was measured by apparent porosity and compressive strength. And its mineral compositions were identified with X-ray diffractometer. The following results were obtained; 1) Optimum amount of mixed clay ($\textrm{Al}_2\textrm{O}_3$ 40 wt% mixed) as a binder was about 25wt% 2) Appropriate mixing ratio of mixed Kaolin chamotte ($\textrm{Al}_2\textrm{O}_3$ 40wt% mixed) was about 30wt% in the clay Kaolin chamotte binder. 3) Variation of apparent porosity and compressive strength of sintered SiC-binder mixture fired at $1350^{\circ}C$ were due to the sinterbility of clay.

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Mineralogy of Kaolin from Hadong-sancheong Area, Korea (하동-산청지역에서 산출되는 고령토의 광물학적 연구)

  • 김수진;정기영;이수재;권석기
    • Journal of the Mineralogical Society of Korea
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    • v.2 no.1
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    • pp.11-17
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    • 1989
  • The kaolin deposits in Hadong-Sancheong area, have been formed by supergene weathering of anorthositic rocks including anorthosite, leucogabbro, and gabbro. Kaolin consists chiefly of halloysite(10$\AA$) and kaolinite with other minerals such as illite, vermiculite, plagioclase, hornblende, quartz amorphous materials(allophane and siica), goethite, and hematite. Goethite and hematite are the major coloring agents of the reddish brown and other colored kaolins. Other common accessory minerals are magnetite, ilmentite, anatase, gibbsite, I/S, C/V, chlorite, lithiophorite, and birnessite. Paragonite, dravite, laumontite, clinozoisite, muscovite, scolecite, stellerite are locally found. Al substitution of Fe in goethite and hematite decreases from the surface zone toward the deeper zone. The kaolin deposits show three horizontal zoning; the upper reddish brown, middle pink, and lower white zones. All the zones are characterized by somewhat different mineralogy. The factors for the formation of kaolin deposits in Hadong-Sancheong area are 1) the presence of anorthositic rocks, 2) the low flat or gentle topography, 3) the favorable climate, and 4) the long-continued preservation of kaolins with-out erosion.

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