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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

Colin Dessemond, Gervais Soucy, Jean-Philippe Harvey and Philippe Ouzilleau

Article (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.

Uncontrolled Keywords

spodumene heat treatment; phase transitions; thermodynamic phase diagram; acid leaching lithium extraction

Subjects: 1800 Chemical engineering > 1800 Chemical engineering
1800 Chemical engineering > 1803 Thermodynamics
1800 Chemical engineering > 1804 Heat transfer
1800 Chemical engineering > 1805 Transport processes
1800 Chemical engineering > 1806 Separation processes
Department: Department of Chemical Engineering
Research Center: Other
Funders: Fonds de recherche du Québec-Nature et Technologies (FQRNT), Nemaska Lithium Inc.
Grant number: 2016-MI-192454
PolyPublie URL: https://publications.polymtl.ca/9414/
Journal Title: Minerals (vol. 10, no. 6)
Publisher: MDPI
DOI: 10.3390/min10060519
Official URL: https://doi.org/10.3390/min10060519
Date Deposited: 16 Aug 2023 13:47
Last Modified: 07 Nov 2023 11:38
Cite in APA 7: Dessemond, C., Soucy, G., Harvey, J.-P., & Ouzilleau, P. (2020). Phase transitions in the α–γ–β spodumene thermodynamic system and impact of γ-spodumene on the efficiency of lithium extraction by acid leaching. Minerals, 10(6), 519 (23 pages). https://doi.org/10.3390/min10060519


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