Thermodynamic properties and reaction mechanism of coal reductive decomposition phosphogypsum to prepare CaO and SO2

doi:10.1016/j.cjche.2024.11.011

Chinese Journal of Chemical Engineering ›› 2025, Vol. 79 ›› Issue (3): 135-144.DOI: 10.1016/j.cjche.2024.11.011

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Thermodynamic properties and reaction mechanism of coal reductive decomposition phosphogypsum to prepare CaO and SO₂

Pengxing Yuan¹, Meng Li^2,3, Shiyi Chen¹, Wenguo Xiang¹

1. Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing 211189, China;
2. SINOPEC Nanjing Engineering & Construction Incorporation, Nanjing 210049, China;
3. College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310058, China

Received:2024-06-27 Revised:2024-08-21 Accepted:2024-11-11 Online:2025-01-22 Published:2025-03-28
Supported by:
The authors wish to acknowledge financial support by the Phosphogypsum Low-Temperature Decomposition to Produce Calcium-Based Materials and Sulfuric Acid Raw Gas Technology (Horizontal Project) (8503009049) and National Natural Science Foundation of China (52376101).

Thermodynamic properties and reaction mechanism of coal reductive decomposition phosphogypsum to prepare CaO and SO₂

Pengxing Yuan¹, Meng Li^2,3, Shiyi Chen¹, Wenguo Xiang¹

1. Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing 211189, China;
2. SINOPEC Nanjing Engineering & Construction Incorporation, Nanjing 210049, China;
3. College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310058, China

通讯作者: Shiyi Chen,E-mail:sychen@seu.edu.cn;Wenguo Xiang,E-mail:wgxiang@seu.edu.cn
基金资助:
The authors wish to acknowledge financial support by the Phosphogypsum Low-Temperature Decomposition to Produce Calcium-Based Materials and Sulfuric Acid Raw Gas Technology (Horizontal Project) (8503009049) and National Natural Science Foundation of China (52376101).

Abstract

Abstract: The thermal effects, spontaneity and proceeding degree of 32 chemical reactions during coal reductive decomposition phosphogypsum (PG) to prepare CaO and SO₂ are analyzed utilizing thermodynamic theory and method. The ideal reaction temperature for PG decomposition and desulfurization is 1173–1273 K. The 10 key chemical reactions controlling coal reductive decomposition PG have been selected. The heat release of critical exothermic reactions can satisfy the autothermal operation of PG decomposition and desulfurization process. Meanwhile, the spontaneity of oxidation reactions has thermodynamically priority over reduction reactions. But the reaction mechanism shows that the oxidation of CaS by O₂ is in parallel competition with the reduction of CaSO₄ by CO and C. Furthermore, clarifying the regulatory mechanisms of PG decomposition temperature and reaction atmosphere (reducibility and oxidation) is beneficial for maximizing the production of CaO and SO₂.

Key words: Phosphogypsum, Coal, Thermodynamic, Reductive decomposition, Reaction mechanism

摘要： The thermal effects, spontaneity and proceeding degree of 32 chemical reactions during coal reductive decomposition phosphogypsum (PG) to prepare CaO and SO₂ are analyzed utilizing thermodynamic theory and method. The ideal reaction temperature for PG decomposition and desulfurization is 1173–1273 K. The 10 key chemical reactions controlling coal reductive decomposition PG have been selected. The heat release of critical exothermic reactions can satisfy the autothermal operation of PG decomposition and desulfurization process. Meanwhile, the spontaneity of oxidation reactions has thermodynamically priority over reduction reactions. But the reaction mechanism shows that the oxidation of CaS by O₂ is in parallel competition with the reduction of CaSO₄ by CO and C. Furthermore, clarifying the regulatory mechanisms of PG decomposition temperature and reaction atmosphere (reducibility and oxidation) is beneficial for maximizing the production of CaO and SO₂.

关键词: Phosphogypsum, Coal, Thermodynamic, Reductive decomposition, Reaction mechanism

Pengxing Yuan, Meng Li, Shiyi Chen, Wenguo Xiang. Thermodynamic properties and reaction mechanism of coal reductive decomposition phosphogypsum to prepare CaO and SO₂[J]. Chinese Journal of Chemical Engineering, 2025, 79(3): 135-144.

Pengxing Yuan, Meng Li, Shiyi Chen, Wenguo Xiang. Thermodynamic properties and reaction mechanism of coal reductive decomposition phosphogypsum to prepare CaO and SO₂[J]. 中国化学工程学报, 2025, 79(3): 135-144.

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Thermodynamic properties and reaction mechanism of coal reductive decomposition phosphogypsum to prepare CaO and SO₂

Thermodynamic properties and reaction mechanism of coal reductive decomposition phosphogypsum to prepare CaO and SO₂

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