Phase transformation mechanism of spodumene during its calcination

Arif A. Abdullah, Hans C. Oskierski, Mohammednoor Altarawneh, Gamini Senanayake, Gregory Lumpkin, Bogdan Z. Dlugogorski

    Research output: Contribution to journalArticleResearchpeer-review

    Abstract

    This contribution provides a detailed in-situ account of transformation reactions during calcination of a typical high-grade α-spodumene (α-LiAlSi2O6) concentrate, a pre-treatment step required to refine spodumene into commercial lithium chemicals. We observe four reaction pathways during the transition of spodumene, employing in-situ high-temperature powder XRD measurements using both cathode-tube and synchrotron radiation. At a relatively slow heating rate of 8 °C min−1, we observe a close relationship between the development of γ-spodumene, with an onset temperature of 842 °C, and reduction of the amorphous background, in the collected XRD spectra. This demonstrates that, initially γ-spodumene recrystallises from amorphous spodumene. At the fast initial heating rate of 100 °C min−1, γ-spodumene first appears at a higher temperature of 1025 °C. This mineral subsequently transforms into β-spodumene at high temperatures along the reaction pathways denoted as pathway (1) amorphous spodumene → γ-spodumene → β-spodumene and (3) crystalline α-spodumene → γ-spodumene → β-spodumene. The stability of γ-spodumene strongly depends on the mechanical treatment of the sample, and the heating rate of the calcination process, suggesting high and low activation energies for pathways (3) and (1), respectively. In another experiment, we observe rising peaks of β-quartz, a minor gangue mineral in the spodumene concentrate, that reflect the substitution of Li+ and Al3+ for Si4+ above 875 °C. This phase ultimately transforms to β-spodumene at 975 °C. The same experiment demonstrates the spectrum of β-spodumene continuously increasing in magnitude, above 975 °C, with decreasing abundance of α-spodumene, indicating a direct conversion of α- to β-spodumene. Thus, the two other reaction corridors comprise: (2) crystalline α-spodumene → β-quartzss → β-spodumene; (4) crystalline α-spodumene → β-spodumene. Heating of a finely ground sample results in faster and more-complete conversion of α-spodumene compared to a coarser specimen. Our experiments establish the characteristic temperatures of phase transformations during spodumene calcination and reveal the influence of amorphous material and thermal history on reaction sequences. Approaches that integrate the optimisation of grinding and heating thus bear the potential to reduce the energy requirements of the calcination process, including the extraction of lithium from γ-spodumene formed at a lower temperature.

    Original languageEnglish
    Article number105883
    Pages (from-to)1-10
    Number of pages10
    JournalMinerals Engineering
    Volume140
    Early online date31 Jul 2019
    DOIs
    Publication statusPublished - 15 Aug 2019

    Fingerprint

    Calcination
    Phase transitions
    heating
    Heating rate
    lithium
    Crystalline materials
    transform
    Temperature
    X-ray diffraction
    Lithium
    Minerals
    experiment
    gangue
    Heating
    mineral
    grinding
    activation energy
    Experiments
    Synchrotron radiation
    substitution

    Cite this

    Abdullah, A. A., Oskierski, H. C., Altarawneh, M., Senanayake, G., Lumpkin, G., & Dlugogorski, B. Z. (2019). Phase transformation mechanism of spodumene during its calcination. Minerals Engineering, 140, 1-10. [105883]. https://doi.org/10.1016/j.mineng.2019.105883
    Abdullah, Arif A. ; Oskierski, Hans C. ; Altarawneh, Mohammednoor ; Senanayake, Gamini ; Lumpkin, Gregory ; Dlugogorski, Bogdan Z. / Phase transformation mechanism of spodumene during its calcination. In: Minerals Engineering. 2019 ; Vol. 140. pp. 1-10.
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    title = "Phase transformation mechanism of spodumene during its calcination",
    abstract = "This contribution provides a detailed in-situ account of transformation reactions during calcination of a typical high-grade α-spodumene (α-LiAlSi2O6) concentrate, a pre-treatment step required to refine spodumene into commercial lithium chemicals. We observe four reaction pathways during the transition of spodumene, employing in-situ high-temperature powder XRD measurements using both cathode-tube and synchrotron radiation. At a relatively slow heating rate of 8 °C min−1, we observe a close relationship between the development of γ-spodumene, with an onset temperature of 842 °C, and reduction of the amorphous background, in the collected XRD spectra. This demonstrates that, initially γ-spodumene recrystallises from amorphous spodumene. At the fast initial heating rate of 100 °C min−1, γ-spodumene first appears at a higher temperature of 1025 °C. This mineral subsequently transforms into β-spodumene at high temperatures along the reaction pathways denoted as pathway (1) amorphous spodumene → γ-spodumene → β-spodumene and (3) crystalline α-spodumene → γ-spodumene → β-spodumene. The stability of γ-spodumene strongly depends on the mechanical treatment of the sample, and the heating rate of the calcination process, suggesting high and low activation energies for pathways (3) and (1), respectively. In another experiment, we observe rising peaks of β-quartz, a minor gangue mineral in the spodumene concentrate, that reflect the substitution of Li+ and Al3+ for Si4+ above 875 °C. This phase ultimately transforms to β-spodumene at 975 °C. The same experiment demonstrates the spectrum of β-spodumene continuously increasing in magnitude, above 975 °C, with decreasing abundance of α-spodumene, indicating a direct conversion of α- to β-spodumene. Thus, the two other reaction corridors comprise: (2) crystalline α-spodumene → β-quartzss → β-spodumene; (4) crystalline α-spodumene → β-spodumene. Heating of a finely ground sample results in faster and more-complete conversion of α-spodumene compared to a coarser specimen. Our experiments establish the characteristic temperatures of phase transformations during spodumene calcination and reveal the influence of amorphous material and thermal history on reaction sequences. Approaches that integrate the optimisation of grinding and heating thus bear the potential to reduce the energy requirements of the calcination process, including the extraction of lithium from γ-spodumene formed at a lower temperature.",
    keywords = "Calcination of α-spodumene, Decrepitation of α-spodumene, Lithium extraction, Lithium pegmatites, Lithium refining, Phase transitions of spodumene",
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    Abdullah, AA, Oskierski, HC, Altarawneh, M, Senanayake, G, Lumpkin, G & Dlugogorski, BZ 2019, 'Phase transformation mechanism of spodumene during its calcination' Minerals Engineering, vol. 140, 105883, pp. 1-10. https://doi.org/10.1016/j.mineng.2019.105883

    Phase transformation mechanism of spodumene during its calcination. / Abdullah, Arif A.; Oskierski, Hans C.; Altarawneh, Mohammednoor; Senanayake, Gamini; Lumpkin, Gregory; Dlugogorski, Bogdan Z.

    In: Minerals Engineering, Vol. 140, 105883, 15.08.2019, p. 1-10.

    Research output: Contribution to journalArticleResearchpeer-review

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    AU - Abdullah, Arif A.

    AU - Oskierski, Hans C.

    AU - Altarawneh, Mohammednoor

    AU - Senanayake, Gamini

    AU - Lumpkin, Gregory

    AU - Dlugogorski, Bogdan Z.

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    N2 - This contribution provides a detailed in-situ account of transformation reactions during calcination of a typical high-grade α-spodumene (α-LiAlSi2O6) concentrate, a pre-treatment step required to refine spodumene into commercial lithium chemicals. We observe four reaction pathways during the transition of spodumene, employing in-situ high-temperature powder XRD measurements using both cathode-tube and synchrotron radiation. At a relatively slow heating rate of 8 °C min−1, we observe a close relationship between the development of γ-spodumene, with an onset temperature of 842 °C, and reduction of the amorphous background, in the collected XRD spectra. This demonstrates that, initially γ-spodumene recrystallises from amorphous spodumene. At the fast initial heating rate of 100 °C min−1, γ-spodumene first appears at a higher temperature of 1025 °C. This mineral subsequently transforms into β-spodumene at high temperatures along the reaction pathways denoted as pathway (1) amorphous spodumene → γ-spodumene → β-spodumene and (3) crystalline α-spodumene → γ-spodumene → β-spodumene. The stability of γ-spodumene strongly depends on the mechanical treatment of the sample, and the heating rate of the calcination process, suggesting high and low activation energies for pathways (3) and (1), respectively. In another experiment, we observe rising peaks of β-quartz, a minor gangue mineral in the spodumene concentrate, that reflect the substitution of Li+ and Al3+ for Si4+ above 875 °C. This phase ultimately transforms to β-spodumene at 975 °C. The same experiment demonstrates the spectrum of β-spodumene continuously increasing in magnitude, above 975 °C, with decreasing abundance of α-spodumene, indicating a direct conversion of α- to β-spodumene. Thus, the two other reaction corridors comprise: (2) crystalline α-spodumene → β-quartzss → β-spodumene; (4) crystalline α-spodumene → β-spodumene. Heating of a finely ground sample results in faster and more-complete conversion of α-spodumene compared to a coarser specimen. Our experiments establish the characteristic temperatures of phase transformations during spodumene calcination and reveal the influence of amorphous material and thermal history on reaction sequences. Approaches that integrate the optimisation of grinding and heating thus bear the potential to reduce the energy requirements of the calcination process, including the extraction of lithium from γ-spodumene formed at a lower temperature.

    AB - This contribution provides a detailed in-situ account of transformation reactions during calcination of a typical high-grade α-spodumene (α-LiAlSi2O6) concentrate, a pre-treatment step required to refine spodumene into commercial lithium chemicals. We observe four reaction pathways during the transition of spodumene, employing in-situ high-temperature powder XRD measurements using both cathode-tube and synchrotron radiation. At a relatively slow heating rate of 8 °C min−1, we observe a close relationship between the development of γ-spodumene, with an onset temperature of 842 °C, and reduction of the amorphous background, in the collected XRD spectra. This demonstrates that, initially γ-spodumene recrystallises from amorphous spodumene. At the fast initial heating rate of 100 °C min−1, γ-spodumene first appears at a higher temperature of 1025 °C. This mineral subsequently transforms into β-spodumene at high temperatures along the reaction pathways denoted as pathway (1) amorphous spodumene → γ-spodumene → β-spodumene and (3) crystalline α-spodumene → γ-spodumene → β-spodumene. The stability of γ-spodumene strongly depends on the mechanical treatment of the sample, and the heating rate of the calcination process, suggesting high and low activation energies for pathways (3) and (1), respectively. In another experiment, we observe rising peaks of β-quartz, a minor gangue mineral in the spodumene concentrate, that reflect the substitution of Li+ and Al3+ for Si4+ above 875 °C. This phase ultimately transforms to β-spodumene at 975 °C. The same experiment demonstrates the spectrum of β-spodumene continuously increasing in magnitude, above 975 °C, with decreasing abundance of α-spodumene, indicating a direct conversion of α- to β-spodumene. Thus, the two other reaction corridors comprise: (2) crystalline α-spodumene → β-quartzss → β-spodumene; (4) crystalline α-spodumene → β-spodumene. Heating of a finely ground sample results in faster and more-complete conversion of α-spodumene compared to a coarser specimen. Our experiments establish the characteristic temperatures of phase transformations during spodumene calcination and reveal the influence of amorphous material and thermal history on reaction sequences. Approaches that integrate the optimisation of grinding and heating thus bear the potential to reduce the energy requirements of the calcination process, including the extraction of lithium from γ-spodumene formed at a lower temperature.

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    KW - Decrepitation of α-spodumene

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    Abdullah AA, Oskierski HC, Altarawneh M, Senanayake G, Lumpkin G, Dlugogorski BZ. Phase transformation mechanism of spodumene during its calcination. Minerals Engineering. 2019 Aug 15;140:1-10. 105883. https://doi.org/10.1016/j.mineng.2019.105883