Effect of collapse column structure on oxidation and physicochemical characteristics of bituminous coal

To investigate the influence of the collapse column structure on the oxidation characteristics of coal, with the aim of preventing mine fires and ensuring the safety of life and property, low-temperature N-2 adsorption, synchronous thermal analysis and enclosed coal oxidation experiments were carried out to analyze the pore structure and macroscopic oxidation characteristics of 3 coal samples (XL1, XL2, XL3) from different affected areas of the collapse column structure in the 1202 working face of Duanwang Mine. C-13 NMR and XPS experiments were conducted to explore the microscopic differences in chemical structure, surface chemical properties, etc. among them. Meanwhile, coal macromolecular models were constructed for ReaxFF pyrolysis simulation. The results show that compared with the original coal XL2, the pores in coal sample XL3 are more developed. The ignition temperatures for XL1, XL2, and XL3 are 510.74 degrees C, 492.81 degrees C, and 482.43 degrees C, respectively. The initial oxygen consumption rate of coal sample XL3 increased by 150 % compared to XL2, while that of XL1 decreased by 37.5 %. The O/C atomic ratio of XL3 is about 2.0 times that of XL2, and about 2.4 times that of XL1. The A/C ratios (The ratio of aromatic carbon content to alkyl carbon content) of XL1, XL2 and XL3 are 4.866, 3.367 and 3.522, respectively. The molecular formulas for XL1, XL2, and XL3 are C154H80O17N2S2, C156H97O30N2S1, and C156H87O33N2S1, respectively. In the ReaxFF pyrolysis simulation, the occurrence order of indicator gases CO, C2H4, C2H2 is XL3, XL2, XL1, respectively.