Study on the characteristics and mechanism of a new type of antioxidant gel foam for coal spontaneous combustion prevention

Aiming at solving the problem of coal spontaneous combustion during coal mining, a new type of antioxidant gel foam for coal mine fire prevention and control was proposed. The gel was prepared by introducing procyanidins into the gel system (sodium silicate / coagulant / bentonite). By testing the gelling time and water retention rate of the antioxidant gel, the effects of different concentrations of coagulant and crosslinker on the performance of antioxidant gel were analyzed. The results of thermogravimetric analysis disclose that the gel corresponds to just about 13% weight loss, and procyanidins in the gel inhibits coal oxidation, thus delaying the decomposition process of coal. The results of inhibition experiment show that the antioxidant gel foam can effectively slow down the oxidation-induced heat release of coal and suppress the increase in coal temperature. Besides, it effectively inhibits the release of CO during coal spontaneous combustion, the inhibition rate reaching up to 68.7%. The results of fire extinguishing experiment display that the gel can well cover the surface of combusting coal to rapidly reduce the temperature at coal center within 900 s and lower the temperature from 727 °C to room temperature within 1850 s, achieving stable fire extinguishing without reburning.