Fluidization thermal decomposition of sodium fluosilicate

doi:10.1016/j.cjche.2022.08.006

Chinese Journal of Chemical Engineering ›› 2023, Vol. 57 ›› Issue (5): 329-337.DOI: 10.1016/j.cjche.2022.08.006

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Fluidization thermal decomposition of sodium fluosilicate

Feng Pan^1,2, Sugang Ma¹, Yu Ge¹, Chuanlin Fan^1,2, Qingshan Zhu^1,2

1. State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences (CAS), Beijing 100190, China;
2. College of Chemical Engineering, University of Chinese Academy of Sciences, Beijing 100049, China

Received:2022-06-01 Revised:2022-08-08 Online:2023-07-08 Published:2023-05-28
Contact: Chuanlin Fan,E-mail:chlfan@ipe.ac.cn;Qingshan Zhu,E-mail:qszhu@ipe.ac.cn
Supported by:
The authors wish to gratefully acknowledge financial support from the National Natural Science Foundation of China (22078326, 21878305, 22078342) and the financial supports of the National Key Research and Development Project of China (2020YFC1909701).

Fluidization thermal decomposition of sodium fluosilicate

Feng Pan^1,2, Sugang Ma¹, Yu Ge¹, Chuanlin Fan^1,2, Qingshan Zhu^1,2

1. State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences (CAS), Beijing 100190, China;
2. College of Chemical Engineering, University of Chinese Academy of Sciences, Beijing 100049, China

通讯作者: Chuanlin Fan,E-mail:chlfan@ipe.ac.cn;Qingshan Zhu,E-mail:qszhu@ipe.ac.cn
基金资助:
The authors wish to gratefully acknowledge financial support from the National Natural Science Foundation of China (22078326, 21878305, 22078342) and the financial supports of the National Key Research and Development Project of China (2020YFC1909701).

Abstract

Abstract: To break through the thermodynamic limitation that sodium fluosilicate only can be completely decomposed at high temperature, the technology of pre-decomposition under SiF₄ atmosphere and deep decomposition under air condition at lower temperature was developed. The hydrolysis reaction of sodium fluosilicate can be effectively restrained when drying under vacuum or low temperature. Thermal decomposition results of sodium fluosilicate indicate that temperature has a very significant effect on its decomposition. The decomposition ratio can reach 79.4% at 600 ℃ for 1 h, and 99.6% at 700 ℃ for 1 h under air condition, respectively. Gas velocity and the type of inert gas have no significant effect on its decomposition. Fine particles affect its decomposition performance due to agglomeration, while coarse particles have good thermal decomposition performance without significant differences. The decomposition reaction process in fluidized bed satisfies the classical Avrami Erofe'EV model, with the reaction order of 1.5 and the activation energy of 61.35 kJ·mol^-1.

Key words: Sodium hexafluorosilicate, Preparation, Silicon tetrafluoride, Absorption, Fluidized bed

摘要： To break through the thermodynamic limitation that sodium fluosilicate only can be completely decomposed at high temperature, the technology of pre-decomposition under SiF₄ atmosphere and deep decomposition under air condition at lower temperature was developed. The hydrolysis reaction of sodium fluosilicate can be effectively restrained when drying under vacuum or low temperature. Thermal decomposition results of sodium fluosilicate indicate that temperature has a very significant effect on its decomposition. The decomposition ratio can reach 79.4% at 600 ℃ for 1 h, and 99.6% at 700 ℃ for 1 h under air condition, respectively. Gas velocity and the type of inert gas have no significant effect on its decomposition. Fine particles affect its decomposition performance due to agglomeration, while coarse particles have good thermal decomposition performance without significant differences. The decomposition reaction process in fluidized bed satisfies the classical Avrami Erofe'EV model, with the reaction order of 1.5 and the activation energy of 61.35 kJ·mol^-1.

关键词: Sodium hexafluorosilicate, Preparation, Silicon tetrafluoride, Absorption, Fluidized bed

Feng Pan, Sugang Ma, Yu Ge, Chuanlin Fan, Qingshan Zhu. Fluidization thermal decomposition of sodium fluosilicate[J]. Chinese Journal of Chemical Engineering, 2023, 57(5): 329-337.

Feng Pan, Sugang Ma, Yu Ge, Chuanlin Fan, Qingshan Zhu. Fluidization thermal decomposition of sodium fluosilicate[J]. 中国化学工程学报, 2023, 57(5): 329-337.

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Fluidization thermal decomposition of sodium fluosilicate

Fluidization thermal decomposition of sodium fluosilicate

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