Research on the effect and mechanism of composite phase change materials inhibiting low-temperature oxidation of coal

Coal spontaneous combustion often occurs in hidden areas and is one of the main disasters in mines. The process of coal spontaneous combustion can be effectively blocked by adding inhibitors. A composite phase change material with stable performance and large heat storage was prepared based on the staged characteristics of coal oxidation and the critical temperature point. To further explore the inhibitory properties of the material, three factors were selected: inhibitor concentration, coal samples particle size and coal samples volatilization, and the orthogonal table were used to design the experiment. The variation law of index gas with coal temperature was obtained through the programmed heating device. Compared with the characteristic temperature values of CO occurrence temperature, fire coefficient R₂ = 0.02 and R₃ = 0.1, the range and variance analysis showed that when the addition amount was 4%, the material had the best performance in inhibiting coal oxidation. Then, the effectiveness of range analysis was verified according to the response surface method. According to the infrared spectroscopy experiment, it is found that the composite phase change material effectively reduced the content of oxygen-containing functional groups and methylene groups, and slowed down the process of coal oxidation and self-heating. In addition, during the oxidation process of coal, the material decomposes water molecules to increase the hydroxyl content, which was conducive to reducing the coal temperature.