Preparation of retarding foam based on tea polyphenols and its flame retardancy

In order to effectively control the spontaneous combustion of residual coal in goaf, tea polyphenol （ＴＰ） was added to compound surfactant solution, and a TP foam with good foaming effect, strong stability and excellent flame retardancy was developed. The composition, compound ratio, mass fraction and content of tea polyphenols were determined by foam scanner and interfacial rheometer. The fire suppression performance of TP foam and three-phase foam was compared with cone calorimeter. The experimental results show that when the ratio of anionic surfactant A to zwitterionic surfactant D is 1∶2, when the mass fraction is 0.3%, the foaming time is the shortest, and the 200 mL foam only needs 142 s. The foam is the most homogeneous and fine, with an average particle size of only 0.054 mm. After adding an appropriate amount of tea polyphenols, the foaming performance of the system is improved. When the mass fraction is 0.06%, the foaming volume can reach 179 mL, and the half-life of liquid separation increases from 584 s to 719 s. Tea polyphenols can reduce the number of active groups in coal. Compared with the three-phase foam, the heat release rate of TP inhibitor foam decreases from 88.5 kW/m2 to 52.2 kW/m2, and the CO₂ release amount from 1.7 kg/kg to 0.6 kg/kg, and the effect of inhibiting coal spontaneous combustion is remarkable.