Synthesis and Characteristics of Thermosensitive Hydrogel for Extinguishing Coal Mines Fire

Thermosensitive hydrogel shows good application prospect in the prevention of coal spontaneous combustion. In this study, a kind of thermosensitive hydrogel was synthesized by adding sodium polyacrylate (PAAS) and magnesium chloride (MgCl2) into methylcellulose (MC). Single-factor experiments and central composition design（CCD method）were carried out to optimize the gel ratio, the inhibitory effect of the gel on three kinds of bituminous coal was analyzed, a test platform was set up (coal capacity of 200 kg) to test the gel’s fire-fighting performance. Results showed that the optimal preparation ratio of gel was MC: PAAS: MgCl2 = 1.3:2.11:16, resulting in the three response parameters of Y1[gelation time, 50 s], Y2[gel strength, 53 KPa], and Y3[viscosity, 11.6 Pa·s]. Temperature programmed experiment indicated that the gel can reduce the release of CO and C2H4 emission and oxygen consumption rate, thus it raising CPT of long flame coal by 5°C and inhibition rate by 63.71%. After injecting the gel in the burning coal, the thermosensitive hydrogel took phase change and absorbed the high temperature as well as thermal energy, reducing the composite speed of the coal and oxygen, causing the coal fire to go out. Research can provide new ideas for the research and application of gel fire extinguishing agents.