A Novel H-TiO2/gel Co-Stabilized Three-Dimensional Network Synergistic Fire-Retardant Foam Gel for Coal-Pile

A new hollow titanium dioxide (H-TiO2)/gel with a three-dimensional network structure and flame resistance effect was proposed to address the instability and inefficiency of existing foam fire extinguishing agents. Sodium borate and H-TiO2 were added to the mixture of acrylic acid (AA) and acrylamide (AM) to form H-TiO2 foam gel by stirring. Test results showed that the optimal gelation time was 18 min at 40 degrees C, and the concentration of crosslinker and initiator was 0.3 wt. % and 0.4 wt. %. In addition, the test results indicated the successful crosslinking and thermal stability due to the three-dimensional network structure. Rheological properties demonstrated that the optimal concentration of H-TiO2 was 0.1 wt. %, and the half-life of H-TiO2 foam gel reached 50 min. The cone calorimeter test(CCT) results showed that for coal #2 the time to ignition(TTI) of H-TiO2 foam gel was up to 12 times than that of raw coal samples. The maximum heat release rate(HHR) was reduced by 56.59 %, and the minimum total heat release(THR) was decreased by 32.04 %. The flue gas inhibition of bituminous coal #2 was 52.63 %, whereas the maximum smoke production was only 0.0006 m2/s. The delayed performance test of coal showed that H-TiO2 foam gel could improve the ignition time of coal, reduce the exothermic rate and total heat dissipation rate of coal, and have an obvious smoke suppression effect.