Microscopic Structural Evolution of Oxidized Coal Residues with Different Oxidation Degree.
ACS Omega
; 9(25): 27655-27668, 2024 Jun 25.
Article
em En
| MEDLINE
| ID: mdl-38947841
ABSTRACT
Coalfield fires represent a critical environmental and safety concern, warranting a comprehensive understanding of the factors influencing the reactivity of oxidized coal residues within fire zones. This study investigates the influence of the oxygen volume fraction and oxidation temperature on the residual structure of oxidized coal, elucidating the underlying mechanisms driving reduced coal reactivity. The representative oxidation conditions for coalfield fire zones were determined. Through industrial and elemental analyses, complemented by methods such as infrared diffuse reflection, specific surface area determination, and pore size analysis, results indicate that higher temperatures and oxygen levels decrease volatile matter and fixed carbon, notably above 400 °C due to oxygen-deficient combustion. Hydroxyl groups decrease with a rising temperature in high oxygen conditions, while carboxyl groups increase at lower temperatures with elevated oxygen. Oxygen-lean and high-temperature conditions reinforce the coal structure, evidenced by the reduced condensation index in aromatic hydrocarbon. Oxidation alters the pore morphology, progressing from micropores to larger irregular pores through various stages, including pore formation, expansion, and merging. Elevated oxygen levels intensify oxidation, consuming the coal carbon matrix and reducing micropores, hindering internal gas diffusion, which is the key to a reduced coal reactivity in fire zones.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
ACS Omega
Ano de publicação:
2024
Tipo de documento:
Article
País de afiliação:
China