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Thermal behavior of Al(NO3)3·9H2O and its application in preparing Al2O3 and regenerating HNO3.
- Source :
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Process Safety & Environmental Protection: Transactions of the Institution of Chemical Engineers Part B . Oct2023, Vol. 178, p728-738. 11p. - Publication Year :
- 2023
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Abstract
- The new process 'coal gangue/fly ash – HNO 3 pressure leaching (NAPL) –low-temperature pyrolysis' was proposed by our team, which aimed to achieve the transformation of coal-based solid wastes from harmless to Al resource. For cost control, the regeneration of HNO 3 at a low cost was crucial for the process. Following NAPL of coal gangue and fly ash, massive amounts of Al(NO 3) 3 ·9 H 2 O were collected, with a decomposition temperature as low as 523 K. The energy consumption for low-temperature pyrolysis could be supplied by the combustion of residual carbon (6.96 wt%) during the thermal activity of coal gangue, allowing HNO 3 to be regenerated and recycled without extra heat supply. However, little research has been done on the pyrolysis behavior and kinetics of Al(NO 3) 3 ·9 H 2 O, which was examined in this study. The pyrolysis characteristics of Al(NO 3) 3 ·9 H 2 O were assessed by TG-DSC analysis. Further experiments and XRD/FTIR/MS analysis revealed that phase evolution of Al(NO 3) 3 ·9 H 2 O followed the sequence of Al(NO 3) 3 ·9 H 2 O→ Al(NO 3) 3 ·nH 2 O→ Al(NO 3) 3 ·3Al(OH) 3 ·5/2 H 2 O→ AlOOH→ Al 2 O 3. Subsequently, the thermodynamic (∆ G , ∆ H , ∆ S) and kinetic (E a , A) parameters were calculated based on the thermogravimetric data by the iso-conversional methods. And the mechanism models and functions were identified via the Malek method. Finally, the economic evaluation of pyrolysis indicated that 5.04 × 10–3 Nm3 of natural gas was consumed during pyrolysis of one mole Al(NO 3) 3 ·9 H 2 O, equivalent to 44.33 $ per ton of Al 2 O 3. As a basic research of Al(NO 3) 3 ·9 H 2 O pyrolysis, this paper enhances related theories of the NAPL process. [Display omitted] [ABSTRACT FROM AUTHOR]
- Subjects :
- *PYROLYSIS kinetics
*THERMAL coal
*ALUMINUM oxide
*FLY ash
*SOLID waste
Subjects
Details
- Language :
- English
- ISSN :
- 09575820
- Volume :
- 178
- Database :
- Academic Search Index
- Journal :
- Process Safety & Environmental Protection: Transactions of the Institution of Chemical Engineers Part B
- Publication Type :
- Academic Journal
- Accession number :
- 172293098
- Full Text :
- https://doi.org/10.1016/j.psep.2023.08.046