Preparation of Mullite from Kaolin by Dry-Grinding

Kawai, Susumu; Yoshida, Masaaki; Hashizume, Genzo

doi:10.2109/jcersj.98.669

Cited by 15 publications

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“…Mechanical activation enhances geopolymerization reaction, which is apparently depend Weakened bonds are susceptible to alkali activation and easily reacts with (OH) − . Rapture of the aluminosilicate bonds and formation of amorphous structure is well described in mechanically activated kaolinite [24]. On the other hand, milling not only caused decrease of the particle sizes of the powders but also formation of the aluminosilicate (Si-O-Al) bonds between the aluminate and silicate sources and improved homogeneity [25].…”

Section: Geopolymers Prepared From Fly Ashes Activated With Various Mmentioning

confidence: 90%

Reactivity of fly ashes milled in different milling devices

Chu

Davaabal

Kim

et al. 2019

Reviews on Advanced Materials Science

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The effect of two different milling devices, namely attrition mill versus vibration mill, on the reactivity of fly ash was studied. High calcium fly ash from 4th Thermal power station of Ulaanbaatar (Mongolia) was used for the experiments. The raw and processed samples were characterized by XRD, SEM, Particle size distribution, BET, Blaine surface area and density measurements. The efficiency of 1 hour milling was evaluated with the Blaine surface area set to be more than 5000 cm2/g. The physical and chemical properties of the attrition milled fly ash changed not much compared to the vibration milled samples. For example the d50 particle size became reduced from 29 µm to 6 µm by attrition milling and in vibration milled fly ash it was reduced to 7 µm. The density increased from 2.44 g/cm3 of raw fly ash to 2.84 g/cm3 and 2.79 g/cm3 in attrition and vibration milled samples, respectively. Mechanical milling revealed not only a particle size reduction but also the formation of a denser microstructure. As a result the vibration milled fly ash showed a weaker interaction with the alkaline solution (8 M NaOH used here) compared to the attrition milled fly ash. Consequently, compressive strength of the binder prepared using the attrition milled fly ash was higher, 61 MPa, while for vibration milled fly ash it was 49 MPa. For comparison unmilled fly ash, it was 21 MPa.

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Section: Geopolymers Prepared From Fly Ashes Activated With Various Mmentioning

confidence: 90%

Reactivity of fly ashes milled in different milling devices

Chu

Davaabal

Kim

et al. 2019

Reviews on Advanced Materials Science

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“…Kaolinite (Al 2 Si 2 O 5 (OH) 4 ) is a layerlattice clay mineral which, when heated, forms a mixture of mullite and cristobalite (SiO 2 ). If the stoichiometry is adjusted by addition of a reactive alumina such as gibbsite (γ-Al(OH) 3 ), the mixture will form monophase mullite when heated.…”

Section: Introductionmentioning

confidence: 99%

“…The commercial importance of mullite (Al 6 Si 2 O 13 ) as a hightemperature ceramic 1 has led to much interest in its synthesis from mixtures of clay minerals with materials such as aluminas and aluminum hydroxides. Kaolinite (Al 2 Si 2 O 5 (OH) 4 ) is a layerlattice clay mineral which, when heated, forms a mixture of mullite and cristobalite (SiO 2 ). If the stoichiometry is adjusted by addition of a reactive alumina such as gibbsite (γ-Al(OH) 3 ), the mixture will form monophase mullite when heated.…”

Section: Introductionmentioning

confidence: 99%

“…If less reactive forms of alumina, such as α-Al 2 O 3 , are used, temperatures of 1500−1700 °C are necessary for complete formation of mullite . It has been shown that the temperature of mullite formation from aluminosilicate precursors also depends on the preparative methods used and that, in particular, mechanochemical treatment of mixtures may cause significant changes in the temperature dependence of the formation reaction . It has been suggested that grinding mixtures not only enhances the rate of reaction by decreasing the particle size but also introduces the possibility of the formation of new chemical species by mechanochemical reaction. − Temuujin et al have postulated that grinding of kaolinite and gibbsite mixtures results in polymerization of Al−O−Si bonds, thereby creating new precursors from which mullite can be formed upon heating.…”

Section: Introductionmentioning

confidence: 99%

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Multiple-Quantum and Cross-Polarized ²⁷Al MAS NMR of Mechanically Treated Mixtures of Kaolinite and Gibbsite

et al. 2000

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Mixtures of the clay mineral kaolinite with gibbsite, when heated, form mullite, a high-temperature ceramic. The 27 Al multiple-quantum magic angle spinning (MQMAS) NMR technique is used to study the local Al environment in mixtures of kaolinite and gibbsite that have been ground together for varying amounts of time. This mechanical treatment forms new chemical species that are amorphous in nature and, therefore, unsuited to analysis by X-ray diffraction. Both novel and established cross-polarization techniques are employed to characterize the starting materials and mixtures, confirm the spatial proximity of 1 H and 27 Al nuclei, and "edit" the two-dimensional 27 Al MQMAS NMR spectra, thereby allowing overlapping peaks corresponding to octahedral Al sites to be studied.

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Mechanochemical Synthesis of Double Oxides

Soft Mechanochemical Synthesis

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Preparation of Mullite from Kaolin by Dry-Grinding

Cited by 15 publications

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Reactivity of fly ashes milled in different milling devices

Reactivity of fly ashes milled in different milling devices

Multiple-Quantum and Cross-Polarized ²⁷Al MAS NMR of Mechanically Treated Mixtures of Kaolinite and Gibbsite

Mechanochemical Synthesis of Double Oxides

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Preparation of Mullite from Kaolin by Dry-Grinding

Cited by 15 publications

References 0 publications

Reactivity of fly ashes milled in different milling devices

Reactivity of fly ashes milled in different milling devices

Multiple-Quantum and Cross-Polarized 27Al MAS NMR of Mechanically Treated Mixtures of Kaolinite and Gibbsite

Mechanochemical Synthesis of Double Oxides

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Product

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Multiple-Quantum and Cross-Polarized ²⁷Al MAS NMR of Mechanically Treated Mixtures of Kaolinite and Gibbsite