Preparation and Characterization of a Bentonite-Based Hybrid Gel for Coal Spontaneous Combustion Prevention

This paper presents an investigation of the feasibility of intercalating lignocellulose/xanthan gum (XG) and organic polymers into bentonite to obtain an efficient fire extinguishing gel material. The bentonite-based hybrid gel was prepared by adding polyacrylates, Al(OH)₃, lignocellulose, and XG into a bentonite suspension, and the resulting gel was characterized. The results showed that no cracking and powdering were found on the surface of the hybrid gel due to the formation of the cross-linked network in the bentonite, and a wide mesopore size distribution and good thermal stability were observed. The hybrid gel also exhibits a wide range of water adsorption ratios, excellent water retention, adjustable gelation times, shear thinning characteristics, and improved compressive strength (the yield stress reaches up to 13 MPa). Based on these characterizations, the mechanism of hybrid gel formation is proposed. The inhibition performance of the hybrid gel on coal spontaneous combustion indicates that the addition of the gel slows down the oxygen chemisorption and thus increases the ignition temperature. Due to the presence of the hybrid gel in the coal, the crossing point temperatures were increased and the lowest CO concentration was produced.