Development and Performance Study of a New Physicochemical Composite Inhibitor for Coal Spontaneous Combustion Control

In order to restrain the spontaneous combustion of coal and ensure the safety of coal mine, an environment-friendly whole-process-inhibiting hydrogel-tea polyphenols-halloysite nanotubes (HNTs) physicochemical composite inhibitor was prepared. The optimal ratio was determined by response-surface experiment, namely, tea polyphenol 2.42%, neutralization degree 80%, initiator dosage 1.68%, crosslinking agent 1%, and crossing point temperature 159.74°C. Compared with pure hydrogel inhibitor and tea polyphenol hydrogel inhibitor, the composite inhibitor performed superior whole-process inhibition effect, with the lowest oxygen consumption rate, CO, and CO2 production rate. The overall inhibition rate was stable at approximately 55% and its highest value was 58%, which indicated that tea polyphenols and HNTs effectively improved the thermal stability. The radical concentration treated with composite inhibitor was the lowest with the reduction of 2.784 × 1017/g lower than that of raw lignite, which proved that the composite inhibitor improved the inhibiting effect microscopically. Finally, inhibition mechanisms of the composite inhibitor were proposed. The results of this work suggest that composite inhibitor is an effective inhibitor of coal oxidation.