A study conducted by researchers has revealed new insights on the construction of molecular structure models of bituminous coal and the adsorption characteristics of ethylene (C2H4) and acetylene (C2H2) gases. This research addresses the challenge of spontaneous coal combustion, which poses significant risks, including fires and explosions.
The research focused on the coal remnants within abandoned mine areas, particularly coal seams from the South Yi Mine located in Liaoning Province, China. The abandoned coal absorbs gases like C2H4 and C2H2 during the oxidation process, leading to inaccurate concentration data for these gases, which are used as indicators to monitor coal stability.
Through simulation and experimental methods, the study established and optimized the macromolecular structure models of two specific coal samples: S7 and W12. The researchers utilized advanced techniques such as infrared spectroscopy, X-ray photoelectron spectroscopy (XPS), and nuclear magnetic resonance (NMR) to understand the physical and chemical characteristics of these coals.
Notably, the study found the molecular formulas of the coal samples to be C136H92O30N2S for S7 and C129H87O28N2S for W12. The results indicated interesting trends related to gas adsorption; for example, as pressure increases, the adsorption capacity of both C2H4 and C2H2 also rises, though it eventually stabilizes. Conversely, at constant pressure, the adsorption capacity tends to decrease with rising temperatures due to increased gas activity and desorption rates.
Beyond the data, the study highlights the adsorption site preferences for the gases—a key detail for coal mine safety. C2H2 has been found to have more adsorption sites compared to C2H4, which can significantly affect monitoring strategies. "The adsorption sites of C2H2 are more than those of C2H4," noted the authors, emphasizing how these findings could influence the precision of spontaneous combustion detection methods.
By simulating the interaction of gases with coal, the findings also imply potential pathways for improving safety protocols and technologies around coal mining. Considering the substantial risks associated with spontaneous combustion, developing effective monitoring tools is imperative.
Concluding, the authors call for broader investigations using diverse coal types and gas mixtures to advance the precision and reliability of spontaneous combustion prediction technologies. The development of complex multi-component gas adsorption models will refine our approach to monitoring coal stability, leading to enhanced safety measures within mining operations.