Dehydration of Ca3Al2(SiO4)y(OH)4(3−y) (0&lt;y&lt;0.176) studied by neutron thermodiffractometry

Rivas-Mercury, Jose M.; Pena, P.; Aza, Antonio H. De; Turrillas, X.

doi:10.1016/j.jeurceramsoc.2007.12.038

Cited by 45 publications

(18 citation statements)

References 16 publications

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“…TGA analysis (Fig. 3) confirmed that a weight loss of 12 wt.% occurred in a two-step process between 250 ºC and 400 ºC, which can be explained in terms of the reported two-step katoite dehydration [40]. No other substantial weight losses were detected in the TGA.…”

Section: Carbon Sequestration Agentsupporting

confidence: 54%

New method for carbon dioxide mineralization based on phosphogypsum and aluminium-rich industrial wastes resulting in valuable carbonated by-products

Romero-Hermida

Santos

Pérez‐López

et al. 2017

Journal of CO2 Utilization

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A new carbon mineralization method was designed based on a sequestration agent synthesised exclusively from industrial wastes. Phosphogypsum waste from the fertiliser industry was dissolved into caustic aqueous waste from the aluminium anodising industry. The resulting precipitate consisted of katoite (Ca 3 Al 2 (OH) 12 , a Si-free hydrogrossular solid solution end-member of the Al-containing hydrogarnet) and thenardite (Na 2 SO 4 );the latter easily removed by rinsing with water. The carbonation performance of this katoite-rich sequestration agent was evaluated using two different methods: by bubbling in aqueous media, and by weathering. Both procedures yielded high carbonation efficiencies (80% and 100%, respectively), and resulted in a solid precipitate composed primarily of calcite (CaCO 3 ) and aluminium hydroxide (Al(OH) 3 ). Priority attention was given to the transfer of trace elements and radionuclides of the uranium series typically present in the phosphogypsum. Results confirmed that the traces were transferred to resulting final solid carbonate at concentrations similar to those present in the raw phosphogypsum. In conclusion, these carbonated minerals would trap substantial amounts of CO 2 and produce final materials with similar civil engineering uses to those proposed for current phosphogypsum wastes. This work offers new methods for jointly manage specific industrial wastes oriented to more sustainable industrial processes and to control CO 2 emissions.

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Section: Carbon Sequestration Agentsupporting

confidence: 54%

New method for carbon dioxide mineralization based on phosphogypsum and aluminium-rich industrial wastes resulting in valuable carbonated by-products

Romero-Hermida

Santos

Pérez‐López

et al. 2017

Journal of CO2 Utilization

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“…Crystalline phases like spinel solid solutions are identified in all samples. The preexisting cancrinite (i.e., in the raw BR) transforms during heat treatment to nepheline, while the gehlenite formation can be explained possibly by hydrogrossular degradation and recrystallization [19,31,32]. These silicates are examples of mineral phases which were not predicted in the thermodynamic calculation for the given compositions, except for Pr_BR.…”

Section: Characterization Of Precursormentioning

confidence: 92%

A Proposal for a 100 % Use of Bauxite Residue Towards Inorganic Polymer Mortar

Hertel

Blanpain

Pontikes

2016

J. Sustain. Metall.

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A new process is suggested in the present work turning bauxite residue (BR) into a ready-made mortar for the synthesis of inorganic polymers, effectively transforming the Bayer process into a zero-waste process. This was achieved by firing BR at 1100°C which supports the formation of liquid phase and results after subsequent fast cooling in a semivitreous material. Based on thermodynamic calculations, the process was subsequently improved by adding minor quantities of C and silica to BR before firing which leads to the carbothermic reduction of ferric iron into ferrous iron; the new blends demonstrated an increase in the melt formation and eventually in the content of amorphous phase after solidification. The resulting material was activated using a K-silicate solution and was cured at 60°C for 72 h. The synthesized materials were water insoluble and dense, demonstrating compressive strength exceeding 40 MPa for the silica-rich blend. These inorganic polymers can find applications in construction, such as pavement tiles or floor/roofing tiles. A possible implementation of the process to transform BR within the alumina refinery is also represented.

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“…Hydroxy-sodalite has previously been observed in NaOH activated fly ash. 12,42,45 The high concentration of Cl in the APC residue would favour the presence of the Cl containing analogue in the samples studied here.…”

Section: Characterisation Of Productsmentioning

confidence: 97%

“…High alkalinity may assist katoite formation by increasing the solubility of Al and the reaction kinetics. Dehydroxylation of katoite has been shown to occur at 250-350uC, 42 and therefore, the DTA endotherm corresponding to this event would overlap with that of Friedel's salt.…”

Section: Characterisation Of Productsmentioning

confidence: 99%

Alkali activated solidification/stabilisation of air pollution control residue using co-fired PFA: mineralogical characterisation

Shirley

Black

2011

Advances in Applied Ceramics

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The paper characterises the phases formed in a solidification/stabilisation (s/s) matrix resulting from a blend of air pollution control residue and co-fired pulverised fuel ashes, activated with a waste, aluminium containing, NaOH solution. Characterisation was performed by X-ray diffraction, simultaneous thermal analysis (thermogravimetric analysis and differential thermal analysis) and SEM. The effects of varying air pollution control/pulverised fuel ashes ratio, curing temperature and time and liquid phase (NaOH or deionised water) on the hydration products in the s/s matrix were studied, as were the changes in phase composition during regulatory leach testing. The principle phases in the s/s matrix, dependent on the process conditions, included Ca(OH) 2 , CaCO 3 , NaCl, C-S-H (I), Friedel's salt, katoite, zeolitic phases Na-P1 and sodalite, CaClOH and vishnevite. Some retention of chlorides within Friedel's salt and sodalite during leach testing was observed; however, most was released due to its presence as NaCl. Sulphates were retained as vishnevite during leach tests.

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Dehydration of Ca3Al2(SiO4)y(OH)4(3−y) (0<y<0.176) studied by neutron thermodiffractometry

Cited by 45 publications

References 16 publications

New method for carbon dioxide mineralization based on phosphogypsum and aluminium-rich industrial wastes resulting in valuable carbonated by-products

New method for carbon dioxide mineralization based on phosphogypsum and aluminium-rich industrial wastes resulting in valuable carbonated by-products

A Proposal for a 100 % Use of Bauxite Residue Towards Inorganic Polymer Mortar

Alkali activated solidification/stabilisation of air pollution control residue using co-fired PFA: mineralogical characterisation

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