Microstructure and properties of sintered mullite developed from Indian bauxite

Tripathi, Himanshu; Ghosh, Arup; Halder, Manas Kamal; Mukherjee, B; Maiti, Himadri Sekhar

doi:10.1007/s12034-012-0337-z

Cited by 23 publications

(18 citation statements)

References 15 publications

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“…Many workers have attended the problem and trying to reduce the effect of these impurity phases on the overall refractory properties. Our previous study shows that selective removal of CaO by acid leaching of bauxite greatly improved the refractory properties . After selective removal of CaO, other impurity phases, such as TiO 2 and Fe 2 O 3 , enter into in situ formed mullite phase by solid solution during reactive sintering, which was confirmed by an enhancement in unit cell parameters of mullite .…”

Section: Introductionmentioning

confidence: 79%

“…India is blessed with a huge resource of bauxite minerals, but out of total available resources, only 1% is of refractory grade, as it contains a considerable amount of impurities, that is, TiO 2 , Fe 2 O 3 , and CaO . In its present form, it shows very low refractory properties due to the formation of low melting phases at higher temperature.…”

Section: Introductionmentioning

confidence: 99%

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Mechanical Properties of Mullite–Corundum Composites Prepared from Bauxite

Maldhure

Tripathi

Ghosh

2014

Int J Applied Ceramic Tech

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Mullite–corundum composites have been prepared by reaction sintering of Indian bauxite having considerable amount of impurities and silica sol. The effect of changing mullite phase proportion on the mechanical properties (i.e., flexural strength, elastic modulus, hot modulus of rupture, thermal shock resistance) of prepared composites has been studied. Flexural strength and elastic modulus increase with increasing free corundum phase content in the composites. Hot modulus of rupture for the sample containing only mullite phase increases with increasing test temperature over entire temperature range. Theoretical thermal shock resistance parameters R and R‴ are well supported by experimental thermal shock data.

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Section: Introductionmentioning

confidence: 79%

Section: Introductionmentioning

confidence: 99%

Mechanical Properties of Mullite–Corundum Composites Prepared from Bauxite

Maldhure

Tripathi

Ghosh

2014

Int J Applied Ceramic Tech

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“…The chemical analysis of the as-received bauxite was done by standard wet chemical methods as discussed elsewhere. 18 CaO was removed from bauxite by acid leaching (10% HCl) for 4 h. As-received bauxite ore was crushed and ground to pass though 100 mesh sieve. 1 kg ground bauxite was mixed in 2 L 10% HCl and was stirred for 4 h. The mixture was allowed to settle down to remove the acidic water followed by washing by water for several times until the mixture shows pH around 7.…”

Section: Methodsmentioning

confidence: 99%

“…The formation of solid solution is responsible for the uneven growth of mullite. 18 Figure 6d shows high packing of alumina particles among the coarser mullite grains. The crystalline phases are bonded together by vitreous phase with high packing and low porosity.…”

Section: Scanning Electron Microscopy (Sem)mentioning

confidence: 95%

Mullite-Corundum Composites from Bauxite: Effect of Chemical Composition

Maldhure

Tripathi

Ghosh

et al. 2014

Transactions of the Indian Ceramic Society

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In situ mullite-corundum composites have been prepared from low grade Indian bauxite containing high percentage of impurities (SiO 2 , Fe 2 O 3 , TiO 2 , CaO) and silica sol to study the effect of different mullite proportions on the refractory properties. Formation of different phases has been identified by X-ray diffractometry and the microstructure has been studied by field emission scanning electron microscopy. XRD analysis shows the presence of mainly mullite and corundum peaks. The bulk density increases and apparent porosity decreases with decreasing amount of mullite phase proportion in the mullite-corundum sintered aggregate. Refractoriness under load of mullitecorundum composites increases with increasing corundum amount up to a certain level and then decreases marginally. The unit cell parameter and cell volume calculated from X-ray diffraction data for mullite also follows the similar trend.

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“…Avoiding extensive Na 2 CO 3 consumption is desired by researchers and industries who are concerned with low-grade resources. Tripathi et al [22] found that the occurrence of sintered grains was related to their chemical compositions. Le et al [23] proposed a heat transfer mechanism by testing microstructures which involves preheating by vapors and decreasing the penetration depth of the outer layer.…”

Section: Introductionmentioning

confidence: 99%

Promote Alumina Leaching through Re-Pelleting: Effects of Directional Coating of Calcite on Silicate Grains

Hu¹,

Qiu²,

Wei³

et al. 2018

Minerals

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Abstract:The contents of Fe and SiO 2 in ferric bauxite are much higher than that in regular bauxite, and the leaching yield of Al 2 O 3 from ferric bauxite cannot reach the general level of ordinary ores, even under optimal conditions. This paper introduces a pretreatment method to enhance sintering before leaching. First, mixing followed by grinding was found to be more efficient than grinding followed by mixing as a pretreatment method by forming a directional coating structure of CaCO 3 on the SiO 2 surface. Second, leaching yields increased grinding fineness because CaCO 3 grain uniformity could be improved with the latter method. Finally, the leaching yields were increased by pulp consistency under certain conditions, as evidenced by improvements in CaCO 3 uniformity, bulk density, and Al 2 O 3 grain size, which parameters were beneficial to enhance leaching. The leaching yield of Al 2 O 3 was increased from 75.2% to 87.15% by using the proposed mixing-grinding method with the leaching agent of water.

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Microstructure and properties of sintered mullite developed from Indian bauxite

Cited by 23 publications

References 15 publications

Mechanical Properties of Mullite–Corundum Composites Prepared from Bauxite

Mechanical Properties of Mullite–Corundum Composites Prepared from Bauxite

Mullite-Corundum Composites from Bauxite: Effect of Chemical Composition

Promote Alumina Leaching through Re-Pelleting: Effects of Directional Coating of Calcite on Silicate Grains

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