Thermokinetic Characteristics of Coal by Multi Kinetics Methods and TG–MS and TG-DSC-FTIR: A Case of the Dananhu Second Mine of Xinjiang

In response to the spontaneous combustion hazards occurring during the mining of multiple coal seams at the Dananhu second mine in Xinjiang, this study aims to enhance the understanding of the combustion mechanism in this open-pit mining. Utilizing thermogravimetric analysis (TG) coupled with mass spectrometry (MS) and simultaneous thermal analysis involving thermogravimetry (TG), differential scanning calorimetry (DSC), and Fourier-transform infrared spectroscopy (FTIR), key parameters such as mass variation, gaseous products, and functional groups during the coal combustion process were systematically obtained. The self-ignition propensity classification for the various coal seams was determined to be at Level I, indicating a high susceptibility to spontaneous combustion. Gaussian fitting quantified the contributions of different mechanisms to mass loss. The study analyzed the intensity of ionic flows from oxidation products and the characteristics of infrared spectra with temperature variations, revealing that the ionic flow intensities of gas components, such as CO, CH4, and CO2, were significantly greater than those of C2H2 and C3H6. Characteristic peaks of CO2, CO, gaseous water, and CH4 were identified. Kinetic characteristics were analyzed using model-free methods (KAS, FWO, Starink) as well as model-fitting approaches. The results from the model-fitting methods indicated a strong linear relationship between ln-(A) and E a under varying heating rates, demonstrating an effective compensation effect during the pyrolysis process of the coal samples. As the loading rate increases, a change in the kinetic mechanism function is observed. This study provides critical insights into the understanding of combustion mechanisms in the Xinjiang region.