A Lab-Scale Experiment on the Spontaneous Combustion Behavior of Chronic Naturally–Oxidized Coal in Re-Mining Coal Mine

ABSTRACT

Spontaneous combustion of coal in re-mining coal mine is a serious threat to the safety recovery of coal resources. In this paper, six coal samples, including two raw bituminous coal samples from the new mining working face and four oxidized bituminous coal samples from the re-mining working face, are selected. The pore structures, thermogravimetric properties, and spontaneous combustion characteristics of raw coal and oxidized coal are studied. The pore structures show that the surface of oxidized coals has more cracks and higher macropore volume and porosity as compared with raw coal. The thermogravimetric experiments demonstrate that the oxidized coal has a higher combustion rate and turns to the combustion reaction zone in advance. Moreover, the oxidized coals perform a better combustion property by showing a comprehensive combustion index of 6.7 × 10⁻⁹ min⁻²·°C⁻³ and 8.9 × 10⁻⁹ min⁻²·°C⁻³, higher than the raw coal of 4.0 × 10⁻⁹ min⁻²·°C⁻³. The spontaneous combustion characteristics show that the oxidized coal performs a greater rate of oxygen consumption and more oxidation products released than raw coal. The CPT of raw coal is higher than 157°C, while the CPT of oxidized coal is between 132°C and 140°C. The research results can provide a risk assessment method for coal spontaneous combustion in the re-mining coal mine, and provide guidance for avoiding the occurrence of coal fires.

KEYWORDS:

• Spontaneous combustion of coal
• coal re-mining
• thermogravimetric properties
• propensity index

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contribution

Dong Ma: Methodology, Software, Investigation, Validation, Visualization, Data curation, Writing – original draft. Leilin Zhang: Supervision, Conceptualization, Resources, Writing – review & editing, Project administration, Funding acquisition.

Yixuan Yang: Data curation, Investigation.

Qigeng Zhou: Software, review & editing.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [52204250], and the Independent Research Project of State Key Laboratory for Fine Exploration and Intelligent Development of Coal Resources, CUMT [SKLCRSM23X007].