Andalusite‐Based High‐Alumina Castables

Rebouillat, Lionel; Rigaud, M.

doi:10.1111/j.1151-2916.2002.tb00099.x

Cited by 27 publications

(21 citation statements)

References 7 publications

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“…The volumetric variation of the crystal phases alone, i.e. andalusite to mullite crystals, is -18%, while the glass volume variation is +22% (bulk densities of silica glass, andalusite and mullite are 2.2-2.6, 3.15 and 3.2 g/cm 3 , respectively) [23]. The differences in the densities cause expansion at higher temperatures (1350 ˚C).…”

Section: Effect Of Microsilica/cement Ratio On Permanent Linear Changmentioning

confidence: 98%

The effect of microsilica and refractory cement content on the properties of andalusite based Low Cement Castables used in aluminum casthouse

et al. 2010

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The bonding system in low cement castables is achieved by the use of calcium aluminate cement, microsilica and reactive alumina. The lime/silica ratio critically impacts the liquid phase formation at high temperatures and subsequently the corrosion resistance and the mechanical and physical properties of the refractory. In the current study, the effects of microsilica and cement contents on the corrosion resistance and the physical and mechanical properties of Andalusite Low Cement Castables (LCCs) refractories were investigated. Alcoa Cup test was used to evaluate the corrosion resistance of the castables at 850 ºC and 1160 ºC. The study showed that an increase in the microsilica/cement ratio improves the physical and mechanical properties of the castable, but at the expense of the corrosion resistance. When a fixed amount of BaSO4 was added to the base refractory material, barium celsian along with glassy phase formation was observed to increase with the increase in the microsilica/cement ratio in the refractory. The presence of the glassy phases was noted to lower the positive effect of Ba-celsian formation on improving the corrosion resistance of the refractory. The observed results were validated using thermodynamic calculations which indicated that Ba-celsian phase was more resistant than Ca-anorthite for applications involving contact with molten aluminum.

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Section: Effect Of Microsilica/cement Ratio On Permanent Linear Changmentioning

confidence: 98%

The effect of microsilica and refractory cement content on the properties of andalusite based Low Cement Castables used in aluminum casthouse

et al. 2010

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“…The expelled silica-rich phase may react with alumina fines in the matrix forming mullite needles (secondary mullitization) which further strengthen the castable. Several recent investigations have shown that secondary mullitization is indeed promoted in very fine andalusite powder and promising properties of castables with fine andalusite were reported [2,4,6]. On the other hand, a negative effect of expelled silica on high temperature strength was reported for castables containing andalusite aggregates, as it was assumed to promote a liquid phase formation at service temperatures [3,7,8].…”

Section: Introductionmentioning

confidence: 98%

“…In aluminabased castables, high properties may be obtained using a micro-silica addition and alumina fines in the matrix. In a number of recent publications, the potential of incorporating very fine andalusite powder in castables as a source of mullite was explored [1][2][3][4][5][6]. On firing at temperatures above 1250-1300 °C, andalusite transforms to a mullite, releasing silica-rich amorphous phase.…”

Section: Introductionmentioning

confidence: 99%

Effects of Andalusite Grain Size on Microstructure and Mechanical Properties of Low Cement Alumina-Based Castables

Brisson¹,

Paransky²,

Rigaud³

2003

Canadian Metallurgical Quarterly

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Three high alumina-based, low cement castables each containing a 15% addition of andalusite of different grain size were compared to a similar castable containing micro-silica (3.7%) and no andalusite. All castables were fired at 1450 °C for 12 hours. High temperature mechanical properties of the castables were measured employing a wedge splitting test (WST). While the castable with the micro-silica addition exhibited superior strength properties, both strength and work-of-fracture values at high temperature improved in castables containing ultra fine andalusite powder. Microstructural factors leading to the observed differences in properties are discussed.Résumé -On a comparé trois bétons réfractaires à contenu élevé en alumine mais faible en ciment, chacun contenant une addition de 15% d'andalousite de différentes tailles de grain, avec un béton réfractaire similaire contenant de la micro-silice (3.7%) mais sans andalousite. On a cuit tous les bétons réfractaires à 1450 °C pendant 12 heures. On a mesuré les propriétés mécaniques à haute température des bétons réfractaires en employant un test d'écartèlement par enfoncement d'un coin (WST). Alors que le béton réfractaire avec addition de micro-silice exhibait des propriétés mécaniques supérieures, tant les valeurs de résistance que de travail de rupture à haute température se sont améliorées pour les bétons réfractaires contenant de la poudre d'andalousite ultra-fine. On discute des facteurs de microstructure conduisant aux différences observées.

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“…Alumina-based refractories can be classified into low-alumina, containing less than 50% Al 2 O 3 , and high-alumina or bauxite, containing between 50 and 90% Al 2 O 3 . High-alumina refractories have widespread applications in high-temperature metal extraction processes due to their outstanding thermochemical and thermomechanical properties and stability (Rebouillat and Rigaud, 2002;Frulli, 2016). The typical chemical composition of refractory-grade bauxite consists of 85-90 wt.% Al 2 O 3 , 5-10 wt.% SiO 2 , 1-2wt.% Fe 2 O 3 , 3-4 wt.% TiO 2 , 0.4-0.8 wt.% CaO + MgO, and 0.20-0.8 wt.% K 2 O + Na 2 O (Nyoka et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Effect of reclaimed bauxite on andalusite-based refractory castables for tundish applications

Matinde¹,

Msibi²

2019

J. S. Afr. Inst. Min. Metall.

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The robust nature of alumina refractory materials presents opportunities for their in-process reclaiming and re-use in non-critical applications. Virgin refractories can be substituted with different quantities of reclaimed materials without compromising the quality of the refractory products. In this study, the effect of reclaimed bauxite on andalusite-containing refractory castables for tundish applications was investigated. The recycled bauxite was formulated in different proportions to replace virgin andalusite in the castables. Standard tests were conducted to evaluate the physical, physicochemical, and thermochemical properties of the formulated products. Static corrosion tests were conducted using tundish slag in order to simulate the actual operating conditions. The results show that the standard flow behaviour, open porosity, and bulk density of samples containing up to 22 mass% reclaimed bauxite were comparable to those of the reference castable. However, high-temperature properties such as static corrosion at 1400°C and hot modulus of rupture at 1500°C indicated that there is an upper constraint to the amount of substitution. The study demonstrated direct potential savings of up to 10% when the reclaimed alumina replacement ratio was increased to 22 mass%.

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Andalusite‐Based High‐Alumina Castables

Cited by 27 publications

References 7 publications

The effect of microsilica and refractory cement content on the properties of andalusite based Low Cement Castables used in aluminum casthouse

The effect of microsilica and refractory cement content on the properties of andalusite based Low Cement Castables used in aluminum casthouse

Effects of Andalusite Grain Size on Microstructure and Mechanical Properties of Low Cement Alumina-Based Castables

Effect of reclaimed bauxite on andalusite-based refractory castables for tundish applications

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