Study on the secondary oxidation behavior and microscopic characteristics of oxidized coal gangue.

Spontaneous combustion of coal gangue (CG) hills has caused varieties of secondary disasters that seriously endanger the ecological environment of the world. The emission law of index gases and their oxidation kinetics during the secondary oxidation process of CG with different ranks of oxidation were studied by using the temperature programmed device and online mass spectrometer (MS). Fourier transform infrared spectroscopy (FTIR) was used to reveal the changes of the CG internal active functional groups.

Piezoelectric Effect and Ignition Characteristics of Coal Mine Gob Roof Collapse.

Existing studies of coal self-ignition and impact frictional sparks do not provide valid support for the analysis of ignition sources in all cases of methane explosions in the gob. In this paper, the explosion in the gob of the Renlou coal mine is used to investigate the piezoelectric effect and ignition characteristics of roof collapse in identifying a new ignition source of gas explosion. Experimental and theoretical analyses conclude that the piezoelectric effect is produced by quartz, which is the main constituent of the roof sandstone.

Pyrolysis Characteristics of Jet Coal and Oxidation of Residues in Zhundong Coalfield Fires.

Coalfield fire area reburning is one of the serious disasters in fire prevention and safety production. In this study, a synchronous thermal analyzer was used to conduct isothermal pyrolysis of jet coal at different temperatures, and the reaction characteristic parameters of different pyrolysis residual structures were analyzed. FTIR was used to measure group contents in raw coal and different pyrolysis residues.

Coupling Relation between the Location of Cross-Cut Negative Pressure and Injecting Nitrogen into Coal Mine Goaf.

Injecting nitrogen into goaf has been widely adopted for preventing fire hazards in coal mines. In this paper, the coupling relation between different locations of negative pressure of cross-cut drainage and nitrogen injection was investigated. The minefield data collection was carried out by an in situ beam tube system on the intake airway and return airway of the mine goaf.

Reaction Mechanism of Aldehyde Groups during Coal Self-Heating.

In order to further understand the mechanism of coal self-heating in the initial stage, the aldehyde group was analyzed by using the quantum chemistry methods. The charge distribution, structural parameters, and molecular orbital were analyzed to determine the active sites existing in the structure of aldehyde group. Then, a chemical reaction model including five elementary reaction sequences was established.

Pore structure and its impact on susceptibility to coal spontaneous combustion based on multiscale and multifractal analysis.

The relationship between the properties of coal and its tendency to spontaneous combustion is critical for the environment, safety concerns, and economy. In this study, to eliminate the complex influence of moisture; the samples having similar moisture content were selected from Shanxi and Henan provinces. The chemical properties, physical properties, and tendency of coal samples to spontaneous combustion were characterized based on the conventional analysis, mercury intrusion porosimetry, fractal dimensions, and crossing point temperature (CPT).