Microchemical composition and cell dimensions of mullites from refractory-grade South American bauxites

Schneider, Hartmut; Wohlleben, Karl

doi:10.1016/0272-8842(81)90009-2

Cited by 12 publications

(7 citation statements)

References 8 publications

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“…3b) its basicity [4], which was 1.70-1.95, was determined. Therefore with a sufficiently high firing temperature the mullite in the investigated bauxites approaches a composition of 2Al2Oa-Si02, which was noted in investigated of foreign bauxites in varieties with relatively high Fe20 ~ and TiO z contents [5].…”

supporting

confidence: 58%

Investigation of the bauxites of Verkhne-Shchugor Deposit of Komi ASSR

Gaenko¹,

Mel'nikova²,

Bragina³

et al. 1989

Refractories

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supporting

confidence: 58%

Investigation of the bauxites of Verkhne-Shchugor Deposit of Komi ASSR

Gaenko¹,

Mel'nikova²,

Bragina³

et al. 1989

Refractories

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“…A survey of the literature data shows that mullite incorporates up to about 12% Fe 2 O 3 while titanium solubility ranges between about 2% and 6% TiO 2 , depending on the synthesis conditions [26]. These incorporations cause strong expansions in the unit cell and were already studied in refractory grade bauxites by Schneider and Wohlleben [27] that found a linear correlation between the impurity incorporation (sum of iron and titanium) and the unit cell parameters, allowing an estimation of Fe 2 O 3 and TiO 2 amounts inside the crystal structure of mullite from the cell parameters. Those researchers used bauxites with Fe 2 O 3 +TiO 2 ranging from 0.43% to 6.9% [27].…”

Section: Resultsmentioning

confidence: 99%

Brazilian refractory grade bauxite: a new alternative to refractories makers and users

Pereira

Reis

Ferreira³

et al. 2019

Cerâmica

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After two centuries of the discovery, we now know that there are several types of bauxites, in which mineralogy points to the most appropriate application. In the non-metallurgical industry, bauxites with refractory grades have been applied as raw materials in the production of high-alumina refractories for both shaped and unshaped. The increase in the cost of other sources of high-alumina raw materials has encouraged the refractory producers to find a more cost-effective substitute, such as refractory-grade calcined bauxites (RGB). Nowadays, concerns rise regarding the availability of RGB due to the continuous restrictions taking place in China, which has a 95% market share. This work presents a new RGB of high-alumina content (~85%) from a Brazilian source in which process enabled a technology with high refractoriness.

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“…Besides this, the Fe 3+, Ti 4+, Ti s+ atoms and others [3,13,26] can occupy the tetrahedral and octahedral positions and can also be incorporated in the statistically distributed structural channels that are located parallel to the c axis and form due to the displacement of A1 atoms during the creation of oxygen vacancies.…”

Section: All-union Institute Of Refractories (Viomentioning

confidence: 99%

“…

…”

mentioning

confidence: 99%

Phase and chemical analysis of a fused refractory based on bauxite concentrate

Соколов¹,

Казаков²,

Tsiporina³

et al. 1987

Refractories

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Bauxite concentrate is a promising raw material for producing high-alumina refractories that are used in the ladles designed for out-of-furnace treatment of steels [i].The purpose of this work is to study the structure and the properties of the fused refractories made from a bauxite concentrate obtained by hydrochloric acid treatment [2].Mullite-based solid solutions (having a basicity >1.5) constitute the main crystalline phase of the refractories obtained from bauxite and its concentrate [2][3][4]. The phase diagram of the AI203-SiO2 system gives an approximate phase constitution of the aluminosilicate refractories (including the fused refractories) as a functionof the chemical composition. According to this diagram, mullite is the only aluminosilicate that is stable at high temperatures. It was established [5][6][7][8][9][10][11][12][13] that the solid solutions of mullite whose composition changes from 3A1203"2Si02 up to 2A!203"Si02 are obtained as a result of a heterovalent substitution 2Si~++C~--~-~2AI~++ 0.In sillimanite, the type (i) substitution leads to a mullite structure having a statistical (random) distribution of oxygen vacancies [] [8, 9, 13]. The following structural formula of mullite was previously suggested [Ii]:where AIVI and AIIV indicate the coordination~ (sites) of aluminum atoms in the octahedral and tetrahedral positions, respectively; and x is the number of oxygen atoms lost per unit structural cell of sillimanite. Cameron [10][11][12] noted that sucha scheme of isomorphous substitution does not restrict the extent of mullitic solid solutions right up to sillimanite [14] on one hand and up to aluminum oxide [15][16][17][18] on the other.The possibility of obtaining mullites of variable composition by electromelting alumina and silica was shown earlier [19].Electromelting of bauxite concentrate and the compositions of the Al2Os-bauxite concentrate-SiO 2 system was carried out in a 'Kristall' unit using a cold crucible having an internal diameter of 65 mm. In order to melt (cast) the specimens of this system, we used high purity (99.99%) aluminum oxide and silica. Electromelting was carried out in air by successive fusion of AI203 and the mixtures of A1203, bauxite concentrate, and silica and an ingot measuring approximately 600 mm in length was obtained. Samples were cut out from the external region of the ingot using a diamond tool. The ingot was subjected to the maximum cooling rate (10-20~ Phase analysis of aluminosilicate refractories is difficult because not only chemical, but also crystallographic transformations occur during the process of their production. In view of this, the methods of rational chemical and x-ray phase analysis are of limited use because chemical analysis requires corrections for the solubility of the phase being analyzed as a function of the particle size, the temperature, and the duration of acid treatment; and x-ray phase analysis needs corrections for the degree of crystallinity of the phases. These facts prompted the application of infrared spectroscopy.Qu...

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Microchemical composition and cell dimensions of mullites from refractory-grade South American bauxites

Cited by 12 publications

References 8 publications

Investigation of the bauxites of Verkhne-Shchugor Deposit of Komi ASSR

Investigation of the bauxites of Verkhne-Shchugor Deposit of Komi ASSR

Brazilian refractory grade bauxite: a new alternative to refractories makers and users

Phase and chemical analysis of a fused refractory based on bauxite concentrate

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