Recognizing and understanding silica-polymorph microcrystals in ceramic glazes

Febo, Roberta Di; Casas, Lluı̀s; Campo, Ángel Adolfo del; Rius, Jordi; Vallcorba, Oriol; Melgarejo, Joan Carles; Capelli, Claudio

doi:10.1016/j.jeurceramsoc.2020.05.063

Cited by 18 publications

(11 citation statements)

References 44 publications

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“…In this work, we used the average temperature ( T av ) to convert the FMB-Oxford hot-air blower set temperature to sample temperature in the quartz capillary for all our experiments. The inversion temperatures of quartz (570 °C) in spodumene concentrate and those in potassium sulfate (580 ° C) in the mixture agree well with literature values of 573 and 584 °C, respectively, , confirming the accuracy of the calibration. The maximum set temperature of 1000 °C used in all in situ S-XRD runs corresponded to a 920 °C sample temperature.…”

Section: Methodssupporting

confidence: 87%

“…Thermal analysis of spodumene concentrate using TGA-DSC shows an endothermic peak at 570 °C, which is the characteristic phase transition of α-quartz to β-quartz. 18 It is followed by an endothermic peak starting at 940 °C, reaching its maximum at 1040 °C and terminating at 1120 °C, which corresponds to α-spodumene conversion to β-spodumene. 2,19 Thermal analysis of potassium sulfate shows an endothermic peak at 580 °C, which is associated with the transition of potassium sulfate from the β to the α polymorph.…”

Section: Resultsmentioning

confidence: 99%

“…Heating of the 1:1 mixture leads to phase inversions of quartz and potassium sulfate at 570 and 580 °C, respectively (Figure 5c), consistent with literature values. 17,18 Both inversions appear as endothermic peaks in the associated heat flow curves, with the quartz inversion in the mixture present as a shoulder on the flank of the potassium sulfate inversion (Figure 5c). With increasing temperature, spodumene in the mixture expands linearly and at a similar rate as that in the concentrate (Figure 5d).…”

Section: Resultsmentioning

confidence: 99%

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Two-Step Reaction Mechanism of Roasting Spodumene with Potassium Sulfate

et al. 2021

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The conventional process of lithium extraction from α-spodumene (LiAlSi 2 O 6 ) is energy-intensive and associated with high byproduct management cost. Here, we investigate an alternative process route that uses potassium sulfate (K 2 SO 4 ) to extract lithium while producing leucite (KAlSi 2 O 6 ), a slow release fertilizer. Presenting the first-ever in situ record of the reaction of α-spodumene with potassium sulfate, we use synchrotron X-ray diffraction (XRD) and differential scanning calorimetry (DSC) to document the reaction sequence during prograde heating. From 780 °C, we observe a broad endothermic DSC peak, abnormal expansion of the α-spodumene structure, and an increase in α-(Li, K)-spodumene peak intensity during heating with potassium sulfate, indicative of the exchange between lithium and potassium in the spodumene structure. When 11 ± 1% K occupancy in the M2 site of α-(Li, K)-spodumene is reached, the mechanism changes from ion exchange to a reconstructive transformation of α-(Li, K)-spodumene into leucite, evidenced by a decrease in α-spodumene and potassium sulfate abundance concurring with formation of leucite over a narrow temperature range between 850 and 890 °C. The increasing background intensity in synchrotron XRD above 870 °C suggests that a lithium sulfate-bearing melt starts to form once >90% of α-spodumene has been converted during the reaction. This fundamental understanding of the reaction between α-spodumene and potassium sulfate will enable future development of lithium extraction routes using additives to significantly decrease energy intensity and to produce marketable byproducts from α-spodumene.

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Section: Methodssupporting

confidence: 87%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Two-Step Reaction Mechanism of Roasting Spodumene with Potassium Sulfate

et al. 2021

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“…For SiO 2 , potassium oxide is a powerful mineralizer, which reacts with silica to activate the crystal lattice, thus enhancing the reaction ability and promoting the solid state reaction of quartz to cristobalite. Cristobalite appears after exposure for a certain time, which confirms further the mineralization that the cristobalite is not a stable phase in the pure silica system [19,22]. It is similar to the result of Fenner's [1], where Na 2 WO 4 was used as the flux.…”

Section: The Existence Of Glass Favors Phase Transition Of Quartzsupporting

confidence: 83%

“…It is widely accepted that highly ordered cristobalite only form at higher temperatures while disordered cristobalite forms in the lower temperature range where tridymite is stable [13,22]. The cristobalite crystallites forms at 900 • C and 1000 • C in this study, which is much lower than the stable temperature of crystallites reported in the literature.…”

Section: The Effect Of Temperature On the Phase Transformation Of Quartz-potassium Silicate Glass Compositecontrasting

confidence: 56%

Microstructure Study of Phase Transformation of Quartz in Potassium Silicate Glass at 900 °C and 1000 °C

Xie

et al. 2021

Crystals

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Interfacial reaction between quartz and potassium silicate glass was studied at both 900 °C and 1000 °C. The results showed that no phase transformation was observed for the pure quartz at 900 °C or 1000 °C. Instead, for quartz particles in K2O-SiO2 glass, the transformation from quartz to cristobalite occurred at the quartz/glass interface at first, and then the cristobalite crystals transformed into tridymite. The tridymite formed at the interface between particles and glass became the site of heterogeneous nucleation, which induces plenty of tridymite precipitation in potassium silicate glass. The influential mechanism of firing temperature and size of quartz particles on transformation rate was discussed.

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Origin, formation, and transformation of different forms of silica in Xuanwei Formation coal, China, and its’ emerging environmental problem

Chen,

Shi,

et al. 2023

Environ Sci Pollut Res

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The study on the origin of quartz and silica in Xuanwei Formation coal in Northwest Yunnan, China, is helpful to understand the relationship between quartz and silica and the high incidence of lung cancer from the root. To address these questions, the mineralogy and microscopic studies of silica in Xuanwei Formation coal were performed.The following results were obtained: (1) silica in the late Permian Xuanwei Formation coal seams originated from detrital input, early diagenesis, and late diagenesis. (2) A more signi cant contribution comes from early diagenesis, which contains abundant authigenic quartz and amorphous silica. (3) Quartz and silica from inorganic silicon are more symbiotic with kaolinite and from biogenic silicon with chamosite. (4) Three silica polymorphs in coal samples have been identi ed: opal-A (amorphous silica), opal-CT/-C (cristobalite/tridymite), and α quartz. ( 5) Opal-A is ubiquitous, while opal-CT/-C and α quartz are rare. (5) Opal-A is an amorphous and nontoxic ordinary silica. Highlights 1. Silica originated from detrital input, early diagenesis, and late diagenesis.2. Early diagenetic silica contains authigenic quartz and amorphous silica.3. Inorganic silica is more symbiotic with kaolinite and biogenic silica with chamosite. 4. Opal-A is ubiquitous, while opal-CT/-C and α quartz are rare. 5. Opal-A is an amorphous and nontoxic ordinary silica.

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Recognizing and understanding silica-polymorph microcrystals in ceramic glazes

Cited by 18 publications

References 44 publications

Two-Step Reaction Mechanism of Roasting Spodumene with Potassium Sulfate

Two-Step Reaction Mechanism of Roasting Spodumene with Potassium Sulfate

Microstructure Study of Phase Transformation of Quartz in Potassium Silicate Glass at 900 °C and 1000 °C

Origin, formation, and transformation of different forms of silica in Xuanwei Formation coal, China, and its’ emerging environmental problem

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