Preparation of foamed gel for preventing spontaneous combustion of coal

Abstract As a fire prevention and extinguishing technology, foamed gel was developed to control spontaneous combustion of coal effectively. Foamed gel is a compositional system formed by a foaming agent, polymers, and N2 through physical foaming. It controls spontaneous combustion of coal by integrating the fire prevention and extinguishing properties of gel and foams. In this study, the influences of the compositional system and the dosage of foaming agent, as well as the type and dosage of polymers, on foam properties were analyzed by experiments. A compositional foaming agent system was prepared by mixing two surfactants at a mass ratio of 1:2. Results show that the foamed gel prepared when the mass fractions of the compositional foaming agent system and the polymer X are 6 and 3 g/L is optimal. Moreover, the retardation performance of the foamed gel was studied. Results demonstrate that the TTI of coal samples with foamed gel is 334 s, which is considerably higher than those of coal samples with MgCl2 and raw materials (167 and 27 s, respectively). The highest HRR of coal sample with foamed gel is only 38.46 kW/m2, which is significantly lower than those of coal samples with MgCl2 and raw materials (62.32 and 68.08 kW/m2). The THR of coal samples with foamed gel is the lowest (28.87 kW/m2) within 1,200 s; meanwhile, the THR of coal samples with MgCl2 and raw coal samples is 45.46 and 49.97 kW/m2, respectively. Therefore, the coal samples with foamed gel have outstanding retardation performance.