## 3 Results and Discussion
### Analysis of Explosion Residues
The TG curve shows that the mass loss began at about 100 \({}^{\circ}\)C and tended to be stable after 186 \({}^{\circ}\)C, so NaHCO\({}_{3}\) was in the thermal decomposition stage at 100-186 \({}^{\circ}\)C. The DSC curve shows two endothermic peaks: at 100 \({}^{\circ}\)C, the NaHCO\({}_{3}\) crystal melted and absorbed heat; 161 \({}^{\circ}\)C corresponds to a strong endothermic peak at which NaHCO\({}_{3}\) was decomposed into NaOH, H\({}_{2}\)O, and CO\({}_{2}\) and absorbed a large amount of heat. As shown in Figure 14c, the TG curve of the MSA-NaHCO\({}_{3}\) composite powder explosion inhibitor contains three steps: 16-100 \({}^{\circ}\)C corresponds to moisture decomposition in MSA;100-200 \({}^{\circ}\)C corresponds to the decomposition of NaHCO\({}_{3}\) (as can be proven by FTIR analysis in Figure 13), and the pyrolysis reaction of metal hydroxide in MSA occurred at 200-800 \({}^{\circ}\)C to form metal oxides. The DSC curve contains two endothermic peaks, mainly corresponding to the endothermic decomposition of NaHCO\({}_{3}\) and metal hydroxides. Obviously, the MSA-NaHCO\({}_{3}\) composite powder explosion inhibitor effectively combined the cooling effects of MSA and NaHCO\({}_{3}\). Figure 14d shows the thermogravimetric curve of oil shale dust. The TG curve shows a slow weight loss at 50-250 \({}^{\circ}\)C, indicating the gradual moisture evaporation in oil shale; 250-550 \({}^{\circ}\)C corresponds to combustion-induced weight loss; 550-800 \({}^{\circ}\)C marks the end of combustion when the curve begins to stabilize. The DSC curve shows an exothermic peak at 489 \({}^{\circ}\)C, suggesting that oil shale dust had the highest combustion reaction speed and the greatest exothermic capacity at 489 \({}^{\circ}\)C. This comparative analysis confirms that the  
Figure 13: The FTIR analysis results of the explosion suppression of oil shale dust by MSA–NaHCO\({}_{3}\) composite powder. optimal pyrolysis temperature range of the MSA-NaHCO\({}_{3}\) composite powder explosion inhibitor is 100-200 \({}^{\circ}\)C. During explosion suppression, before the oil shale dust reached the peak pyrolysis temperature of 489 \({}^{\circ}\)C, the composite inhibitor was able to cool the explosion environment of oil shale dust and keep the ambient temperature from reaching the optimal exploding temperature of oil shale dust. This inhibition effect can also be called physical endothermic cooling effect. Based on the SEM, FTIF, and TGA results, it can be seen that the explosion suppression process of the MSA-NaHCO\({}_{3}\) composite powder explosion inhibitor involves a synergy of physical inhibition and chemical inhibition. The physical inhibition is mainly reflected in the following three aspects. The first is physical coating: MSA and the metal hydroxides (e.g., Al(OH)\({}_{3}\) and Fe(OH)\({}_{3}\)) in MSA generate metal oxides (e.g., Fe\({}_{2}\)O\({}_{3}\) and Al\({}_{2}\)O\({}_{3}\)) to coat the exploded particles. Second is physical endothermic cooling: this refers to the endothermic properties of the metal hydroxides (e.g., Fe(OH)\({}_{3}\) and Al(OH)\({}_{3}\)) in MSA and the NaHCO\({}_{3}\) content in the MSA-NaHCO\({}_{3}\) composite powder explosion inhibitor. The third is gas inerting: the CO\({}_{2}\) produced by the pyrolysis of NaHCO\({}_{3}\) and the water vapor formed by H\({}_{2}\)O compete with O\({}_{2}\) in limited environment. Figure 14: The TG-DSC curves of the target dust. (**a**) the TG–DSC curve of MSA; (**b**) the TG–DSC curve of NaHCO3; (**c**) the TG-DSC curve of the MSA–NaHCO3; (**d**) the TG-DSC curve of the oil shale dust.