Changes in physicochemical properties of α-spodumene by mechanochemical treatment

Gasalla, H.J.; Aglietti, E.F.; López, José Manuel; Pereira, E.

doi:10.1016/0254-0584(87)90088-5

Cited by 18 publications

(11 citation statements)

References 8 publications

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“…However, at higher temperatures, once sufficient nucleation sites are created, the γ-spodumene to β-spodumene reaction mechanism (which may be the nucleation and growth phenomenology suggested by Botto) can readily proceed with a much lower activation energy, hence the higher conversion of α-spodumene for a given heat treatment time. This analysis would be consistent with the suggestion of Gassala et al [20] that grinding spodumene concentrates favors the formation of γ-spodumene at lower heat treatment temperatures through the formation of favorable nucleation sites for this allotrope.…”

Section: Samplesupporting

confidence: 92%

“…According to the literature, this allotropic transformation is linked to irreversible volumetric changes [40]. In addition, the β-spodumene formation is reported as irreversible [7,40], while the α-to-γ allotropic transition is stated as reversible [19,20,40]. The nature of the γ-to-β transition is unknown.…”

Section: Assessing the Irreversibility Of The Allotropic Transformations In Spodumenementioning

confidence: 99%

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Phase Transitions in the α–γ–β Spodumene Thermodynamic System and Impact of γ-Spodumene on the Efficiency of Lithium Extraction by Acid Leaching

et al. 2020

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Heat-treatment of spodumene concentrate at 1323 K (1050 °C) for 30 min in a rotary kiln yielded a successful decrepitation. Particle size decreased from 2 cm to less than 425 µm for 80% of the initial mass. X-ray analysis of both fractions did not reveal the presence of α-spodumene or γ-spodumene. The coarse fraction was ground to less than 425 µm with minimal mechanical energy and mixed with the finer fraction to perform lithium extraction. The lithium extraction efficiency reached 98 wt% without the need for flotation. Some aspects of the thermodynamic behavior of the spodumene system were assessed. Results show that metastable γ-spodumene may hinder the formation of β-spodumene at lower heat treatment temperatures. Some heat-treated samples presented non-negligible γ-spodumene content and lithium extraction efficiency decreases as the γ content increases. Finally, the assumed irreversibility of the transformations was studied by analyzing heat-treated samples following long controlled-storage periods. The results show that concentrate composition is not static over the studied time. This suggests that the β formation is not as irreversible as claimed. It is recommended to avoid long periods between heat-treatment and extraction to avoid the slow conversion of β-spodumene to other allotropes, which are less susceptible to lithium extraction.

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Section: Samplesupporting

confidence: 92%

Section: Assessing the Irreversibility Of The Allotropic Transformations In Spodumenementioning

confidence: 99%

Phase Transitions in the α–γ–β Spodumene Thermodynamic System and Impact of γ-Spodumene on the Efficiency of Lithium Extraction by Acid Leaching

et al. 2020

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“…After heating the amorphous spodumene metastable c-form appears approximately at 800°C which is subsequently converted into b-spodumene at higher temperatures between 900 and 1080°C depending on the experimental conditions (Nordmann and Cheng, 1997;Guo et al, 2006;Kotsupalo et al, 2010;Gasalla et al, 1987). Ferro et al (2004) observed that a rare Li zeolite bikitaite [Li 2 (Al 2 Si 4 O 12 )Á2H 2 O, P1] transforms to c-spodumene at temperature of 800°C and Hurlbut (1957) found the transformation of bikitaite to b-spodumene upon heating to 900°C.…”

Section: Phase Transformation Via C-spodumenementioning

confidence: 98%

“…Amorphization is performed via melting with alloying elements (Nordmann and Cheng, 1997) or via mechanical treatment (Kotsupalo et al, 2010;Gasalla et al, 1987). After heating the amorphous spodumene metastable c-form appears approximately at 800°C which is subsequently converted into b-spodumene at higher temperatures between 900 and 1080°C depending on the experimental conditions (Nordmann and Cheng, 1997;Guo et al, 2006;Kotsupalo et al, 2010;Gasalla et al, 1987).…”

Section: Phase Transformation Via C-spodumenementioning

confidence: 99%

α→γ→β-phase transformation of spodumene with hybrid microwave and conventional furnaces

Peltosaari

Tanskanen

Heikkinen

et al. 2015

Minerals Engineering

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“…Likewise, Moore et al [ 3 ] and Peltosaari et al [ 10 ] recorded 35% and 40% as the highest in their studies, respectively. According to Abdullah et al [ 11 ] and Gasalla et al [ 23 ], the quantity of this phase formed is influenced by the particle size of the feed as well as the heat treatment technique employed; finer particles impact amorphicity which easily recrystallizes into the γ-phase on heating compared to larger-sized particles. The heating rate employed also influences the quantity formed; slow heating rates form higher amounts due to the slow rate of conversion to the β-form.…”

Section: Resultsmentioning

confidence: 99%

Physico-Chemical Characteristics of Spodumene Concentrate and Its Thermal Transformations

et al. 2021

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Spodumene concentrate from the Pilbara region in Western Australia was characterized by X-ray diffraction (XRD), Scanning Electron Microscope Energy Dispersive Spectroscopy (SEM-EDS) and Mineral Liberation Analysis (MLA) to identify and quantify major minerals in the concentrate. Particle diameters ranged from 10 to 200 microns and the degree of liberation of major minerals was found to be more than 90%. The thermal behavior of spodumene and the concentration of its polymorphs were studied by heat treatments in the range of 900 to 1050 °C. All three polymorphs of the mineral (α, γ and β) were identified. Full transformation of the α-phase was achieved at 975 °C and 1000 °C after 240 and 60 min treatments, respectively. SEM images of thermally treated concentrate revealed fracturing of spodumene grains, producing minor cracks initially which became more prominent with increasing temperature. Material disintegration, melting and agglomeration with gangue minerals were also observed at higher temperatures. The metastable γ-phase achieved a peak concentration of 23% after 120 min at 975 °C. We suggest 1050 °C to be the threshold temperature for the process where even a short residence time causes appreciable transformation, however, 1000 °C may be the ideal temperature for processing the concentrate due to the degree of material disintegration and α-phase transformation observed. The application of a first-order kinetic model yields kinetic parameters which fit the experimental data well. The resultant apparent activation energies of 655 and 731 kJ mol−1 obtained for α- and γ-decay, respectively, confirm the strong temperature dependence for the spodumene polymorph transformations.

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Changes in physicochemical properties of α-spodumene by mechanochemical treatment

Cited by 18 publications

References 8 publications

Phase Transitions in the α–γ–β Spodumene Thermodynamic System and Impact of γ-Spodumene on the Efficiency of Lithium Extraction by Acid Leaching

Phase Transitions in the α–γ–β Spodumene Thermodynamic System and Impact of γ-Spodumene on the Efficiency of Lithium Extraction by Acid Leaching

α→γ→β-phase transformation of spodumene with hybrid microwave and conventional furnaces

Physico-Chemical Characteristics of Spodumene Concentrate and Its Thermal Transformations

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