Equations of state and structures of andalusite to 9.8 GPa and sillimanite to 8.5 GPa

Using synchrotron X‐ray diffraction and diamond anvil cells we performed in situ high‐pressure studies of mullite‐type phases of general formula Al4+2xSi2−2xO10−x and differing in the amount of oxygen vacancies: 2:1‐mullite (x = 0.4), 3:2‐mullite (x = 0.25), and sillimanite (x = 0). The structural stability of 2:1‐mullite, 3:2‐mullite, and sillimanite was investigated up to 40.8, 27.3, and 44.6 GPa, respectively, in quasi‐hydrostatic conditions, at ambient temperature. This is the first report of a static high‐pressure investigation of Al2O3–SiO2 mullites. It was found that oxygen vacancies play a significant role in the compression mechanisms of the mullites by decreasing the mechanical stability of the phases with the number of vacancies. Elevated pressure leads to an irreversible amorphization above ~20 GPa for 2:1‐mullite and above 22 GPa for 3:2‐mullite. In sillimanite, only a partial amorphization is observed above 30 GPa. Based on Rietveld structural refinements of high‐pressure X‐ray diffraction patterns, the pressure‐driven evolution of unit cell parameters is presented. The experimental bulk moduli obtained are as follows: K0 = 162(7) GPa with K0′ = 2.2(6) for 2:1‐mullite, K0 = 173(7) GPa with K0′ = 2.3(2) for 3:2‐mullite, K0 = 167(7) GPa with K0′ = 2.1(4) for sillimanite.

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“…on compression up to 5.3 GPa and with data of Burt et al . up to 8.5 GPa . In the sillimanite data of Friedrich et al .…”

Section: Resultsmentioning

confidence: 95%

High‐Pressure Behavior of Mullite: An X‐Ray Diffraction Investigation

Kalita

Schneider²,

Lipinska

et al. 2013

J. Am. Ceram. Soc.

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“…Fig. 9 a,b show clusters around the O1 and O2 sites, respectively, projected on (001) of the andalusite structure including the proposed hydrogen sites (Burt et al 2006(Burt et al , 2007. The O1 site is coordinated by three Al atoms and the O2 site by two Al and one Si atom.…”

Section: E||cmentioning

confidence: 99%

“…Fig. 9 Projection of clusters of the andalusite structure around the O1 site (a) and O2 site (b) based on structural data of Burt et al (2006) plus H at the tetrahedral Si-sites increases (increase of the corresponding OH band). Fig.…”

Section: E||cmentioning

confidence: 99%

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FTIR spectroscopic study of natural andalusite showing electronic Fe–Ti charge-transfer processes: zoning and thermal evolution of OH-vibration bands

Taran¹,

Koch‐Müller

2012

Phys Chem Minerals

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“…Andalusite, with orthorhombic crystals, is one of the most important minerals used in the production of advanced refractory material (Burt et al, 2006;Zhang et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Andalusite Flotation Using Alkyl Benzene Sulfonate as the Collector

Zhou

Zhang

2011

Mineral Processing and Extractive Metallurgy Review

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Andalusite flotation using alkyl benzene sulfonate as the collector has been investigated in this work. This study was performed firstly with a high-grade andalusite sample in a micro-flotation cell and then with an ore sample in a mechanical flotation cell. Electrokinetic measurements showed that the isoelectric point of andalusite was pH 5.2 while that of quartz and biotite these were pH 2.1 and 3.8, respectively. Alkyl benzene sulfonate was found to be effective for andalusite flotation in acidic pH range where andalusite surfaces were positively charged. A pre-treatment by desliming and pre-float (to remove carbonaceous species) followed by flotation produced a concentrate assaying 56.5% Al 2 O 3 at an aluminum recovery of 65.7%.

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Equations of state and structures of andalusite to 9.8 GPa and sillimanite to 8.5 GPa

Cited by 35 publications

References 17 publications

High‐Pressure Behavior of Mullite: An X‐Ray Diffraction Investigation

High‐Pressure Behavior of Mullite: An X‐Ray Diffraction Investigation

FTIR spectroscopic study of natural andalusite showing electronic Fe–Ti charge-transfer processes: zoning and thermal evolution of OH-vibration bands

Andalusite Flotation Using Alkyl Benzene Sulfonate as the Collector

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