Applied Chemical Engineering

Polythermal phase equilibria in the Na2CO3-LiCl-H2O ternary system and crystallization of lithium carbonate

Bakhodir Abdullayev

University of Economics and Pedagogy, Karshi, 180119, Uzbekistan;Karshi State Technical University, Karshi, 180119, Uzbekistan

Dilnoza Axmedova

University of Economics and Pedagogy, Karshi, 180119, Uzbekistan

Jurabek Bozorov

University of Economics and Pedagogy, Karshi, 180119, Uzbekistan

Sarvar Abdiyev

University of Economics and Pedagogy, Karshi, 180119, Uzbekistan

Sanat Samatov

University of Economics and Pedagogy, Karshi, 180119, Uzbekistan

Erkin Yakubov

Karshi State University, Karshi, 180119, Uzbekistan

Khusniddin Botirov

Asian Technology University, Karshi, 180119, Uzbekistan

Murodullo Rakhimov

Tashkent Chemical of Technological Institute, Tashkent, 100001, Uzbekistan

Elbek Mavlanov

Tashkent Chemical of Technological Institute, Tashkent, 100001, Uzbekistan

Tolmas Olimov

Tashkent Chemical of Technological Institute, Tashkent, 100001, Uzbekistan

Odil Mamajonov

Tashkent Chemical of Technological Institute, Tashkent, 100001, Uzbekistan

Mansur Axmedov

Tashkent Chemical of Technological Institute, Tashkent, 100001, Uzbekistan

Miyasar Zhumanova

Tashkent Chemical of Technological Institute, Tashkent, 100001, Uzbekistan

Shavkat Umarov

Jizzakh State Pedagogical University, Jizzakh, 130100, Uzbekistan

Sarvigul Khujanazarova

Karshi State Technical University, Karshi, 180119, Uzbekistan

Murodjon Samadiy

Karshi State Technical University, Karshi, 180119, Uzbekistan

DOI: https://doi.org/10.59429/ace.v9i1.5892

Keywords: Lithium chloride; evaporation; sodium carbonate; cooling; precipitation

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Abstract

Understanding the phase equilibria and solubility behavior in multicomponent salt-water systems is essential for the development of efficient separation and resource recovery technologies, especially for lithium-containing compounds. However, reliable phase equilibrium data for the Na₂CO₃–LiCl–H₂O system remain limited over a wide range of temperatures and concentrations. In this study, solubility relationships and phase transformations in the sodium carbonate–lithium chloride–water system were systematically studied using a visual polythermal method over a wide range of temperatures and compositions. The resulting phase diagram describes distinct crystallization regions corresponding to ice, Na₂CO₃∙10H₂O, Na₂CO₃∙7H₂O, LiCl∙5H₂O, LiCl∙2H₂O, LiCl∙H₂O, and the newly identified Li₂CO₃ phase. The formation and stability of the new lithium carbonate phase were confirmed using combined chemical and physicochemical analysis, including infrared spectroscopy and X-ray diffraction, ensuring the reliability of the obtained equilibrium data. Characteristic absorption bands in the IR spectrum observed at 1437.03 cm^-1 and 869.93 cm^-1 were assigned to carbonate functional groups, providing further evidence for the formation of Li₂CO₃. The polythermal diagram shows that a significant portion of the system is occupied by crystallization fields, indicating the initially low solubility of lithium carbonate. This behavior highlights the possibility of selectively separating Li₂CO₃ from saturated solutions through controlled evaporation. Overall, the results provide fundamental thermodynamic insights and practical recommendations for lithium recovery processes and the development of effective separation strategies in aqueous carbonate-chloride systems.

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