Multifunctional sprayable LiCl@polyacrylamide gel powders for preventing coal spontaneous combustion and dust

A multifunctional LiCl@PAM powder material with both fire prevention and dust suppression functions was prepared. It features simple synthesis, convenient production processes, and sprayability. The physical and chemical structure, water absorption/retention and thermal conductivity of LiCl@PAM gel were investigated. Experimental studies were conducted on the effects of LiCl@PAM gel powders with different salt contents on lignite coal spontaneous combustion (CSC) and dust suppression. Results from FTIR, SEM, water absorption and retention tests, swelling tests, infrared thermal imaging, low-temperature oxidation experiments, thermogravimetric analysis, immersion tests and simulated dust suppression tests showed that the 20 wt%LiCl@PAM gel powder exhibited the best overall performance. This gives it significant advantages in both preventing CSC and suppressing dust. In terms of CSC inhibition, compared to raw coal, the crossing point temperature of 20 wt%LiCl@PAM/coal increased by 33.9 °C and the inhibition rate reached 74.37 % at 90 °C. The apparent activation energies increased by 8.5 kJ/mol (at 30–90 °C) and 10.9 kJ/mol (at 110–190 °C), respectively. In terms of dust suppression, 20 wt%LiCl@PAM showed excellent dust suppression and wetting properties through the combined effect of the strong hygroscopicity of LiCl and the adhesive and agglomeration ability of PAM. This LiCl@PAM powder material provides a novel multifunctional integrated material and solution for the prevention of CSC and dust hazards.