The correlation between the spontaneous combustion tendency of coal and its properties are of great importance for safety issues, environmental concerns, and economic problems. In this study, the relationship between multiple parameters, different from the previous single parameter, and the spontaneous combustion tendency was analyzed. The comprehensive judgment index (CJI), which indicates the tendency of coal spontaneous combustion, was obtained for samples collected from different mines. The CJI was measured by the cross-point temperature and had a negative correlation with the spontaneous combustion tendency. Physical pore structures and chemical functional groups were characterized based on cryogenic nitrogen adsorption and Fourier transform infrared spectroscopy measurements, respectively. For analyzing the effect of coal properties on the spontaneous combustion tendency, the grey relational grade was determined by the grey relational analysis between the CJI and the pore structures and functional groups of coal. The grey relational grade of the benzene substituent with CJI had a maximum of 0.8642, and the macropores had the minimum, 0.4169. The higher the gray relational grade was, the more relevant the spontaneous combustion tendency was, indicating that the benzene substituent was the most relevant. To better predict the spontaneous combustion tendency, the average pore diameter, hydroxyl, methyl, methylene, and benzene substituent with a high grey relational grade were selected. Finally, the multiple regression prediction model of CJI was established. The R squared coefficient, significance level, F-distribution, t-distribution, collinearity diagnosis, and residual distribution of the model met the requirements. In addition, two coal samples were selected to verify the spontaneous combustion tendency model. The relative errors between the predicted CJI value and the experimental CJI value were 1.42 and 4.25%, respectively. These small relative errors verified the reasonableness and validity of the prediction model.

In order to investigate P-containing flame retardant on coal spontaneous combustion, trisodium phosphate, sodium hexametaphosphate, and ammonium polyphosphate were selected. Raw coal and inhibitor solution (10 wt%) were mixed at weight ratio 4:1. Coal (raw coal, inhibited coals) oxidation reaction was measured by own designed temperature-programming device. Simultaneous TG-DSC was carried out. Evolution of CO with increasing temperature and cross point temperature (CPT) were obtained of coal oxidation reaction; these results showed that the addition of (NaPO₃)₆ and ammonium polyphosphate (APP) to raw coal had an obvious suppression effect during low-temperature oxidation. CPT of APP-inhibited coal was 16°C higher than that of raw coal. TG-DTG curve results revealed that characteristic temperatures and mass fraction (ω) of APP-inhibited coal were significantly higher than other coal samples. Initial exothermal temperatures, thermal peak temperatures, and inhibition ratio were obtained from DSC curves. The results all demonstrated that APP had obvious inhibition effects on the whole coal oxidation. Infrared spectrograms of release gases showed that temperatures of the maximum release value and the whole quantity of gas products (CO₂, CH₄, CO, and H₂O) were decreased due to the addition of APP by eliminating free radicals and diluting the amount of oxygen in the surrounding coal sample.

To reveal the CO, CO2, and O-2 adsorption properties of two bituminous coals at different pressures and temperatures, the molecular unit-cell structures of two types of bituminous coal are constructed (C1180H960O120N20 and C1160H860O80N20) by Fourier transform infrared (FTIR) spectroscopy. The bituminous coal molecular FTIR spectroscopic curve is calculated by quantum chemistry, and the results are consistent with the experimental curve. The isothermal adsorption curves of the single-component gases CO, CO2, and O-2 conform to the Langmuir equation from 20 to 60 degrees C. The adsorption simulations are mainly performed using grand canonical Monte Carlo (GCMC) methods. The amount of adsorption decreases with increasing temperature at the same pressure, and CO2 can be the first to reach adsorption saturation at the same temperature. The CO2/CO adsorption selectivity for binary gas mixtures has apparent advantages in low-pressure or shallow buried coal seams. The adsorption selectivity of O-2/CO varying under different pressures is not obvious. The high amount of CO inhibits the adsorption capacity of CO2 and O-2. In other words, the effect of injecting CO2 to control fire extinguishing in bituminous coal seams with high abnormal CO concentrations is not significant.

Abstract  Based on the temporal‐spatial distribution and geochemical characteristics, the Emeishan basalts can be divided into two types: high‐P₂O‐TiO₂ basalt (HPT) and low‐P₂O₅‐TiO₂ basalt (LPT), which differ distinctly in geochemistry: the LPTs are characterized by relatively high abundances of MgO, total FeO and P₂O₅ and compatible elements (Cr, Ni, Sc), and relatively low contents of moderately compatible elements (V, Y, Yb, Co), LREE and other incompatible elements compared with the HPT. On the diagrams of trace element ratios, they are plotted on an approximately linear mixing line between depleted and enriched mantle sources, suggesting that these two types of basalts resulted from interactions of varying degrees between mantle plume and lithospheric mantle containing such volatile‐rich minerals as amphibole and apatite. The source region of the LPT involves a smaller proportion of lithospheric components, while that of the HTP has a larger proportion of lithospheric components. Trachyte is generated by partial melting of the basic igneous rocks at the base of the lower continental crust. Both the two types of magmas underwent certain crystal fractionation and contamination of the lower crust at high‐level magma chambers and en route to the surface.