Spontaneous coal combustion prevention mechanisms of thermosensitive composite hydrogel: An experimental study

Abstract

This study aims to determine the prevention mechanisms of spontaneous coal combustion in thermosensitive composite hydrogels. A thermosensitive composite hydrogel is prepared using methylcellulose, polyethylene glycol, and sodium chloride. A self-designed fire extinguishing experimental device is used to test the inhibitory effects of the thermosensitive composite hydrogel on spontaneous coal combustion. Changes in the water loss rate of the hydrogel under different temperature conditions are also studied. The surface morphology and pore structure of the thermosensitive composite hydrogel are observed by scanning electron microscopy. Finally, the characteristics of the functional groups during the combustion of the coal samples are analysed using a Fourier transform infrared spectrometer. The results show that the thermosensitive composite hydrogel undergoes a phase transformation at temperatures above 58 °C. When the coal sample temperature reaches 200 °C, the cooling and suffocation effects of the hydrogel are optimal because the water loss rate of the hydrogel exceeds 50 %. Furthermore, the hydrogel is firmly coated on the surface of the coal body to prevent any contact between coal and oxygen. In addition, the thermosensitive composite hydrogel generates a strong dehydrating agent and inert gas after thermal decomposition. The collision between gas products and free radicals reduces the effective collision probability between the coal surface active molecules and oxygen, further inhibiting spontaneous coal combustion. These results provide a basis for the practical application of thermosensitive composite hydrogels in underground mines, and guidance for the research and development of thermosensitive composite hydrogel materials.