Investigation on the suppression characteristic of deoxidization gel foam on coal spontaneous combustion

Abstract

Summary Mine fire caused by coal spontaneous combustion is one of the main safety problems in mining. For the purpose of developing a more effective inhibitor to suppress the coal spontaneous combustion, a compound deoxidization gel foam inhibitor was proposed by combining sodium dithionite deoxidizer with gel foam. An experimental platform was self‐built to evaluate the suppression characteristic of deoxidization gel foam. Experimental results showed that the deoxidization gel foam reduced the oxygen concentration to below 14% within 180 minutes. STA‐FTIR test indicated that the deoxidization gel foam raised the active temperature from 250.57°C to 275.18°C and reduced CO2 absorption peak from 0.2926 to 0.2201 at the reaction temperature 20°C. The activation energy was also increased from 85.69 to 95.59 kJ·mol−1 in thermal decomposition combustion that exhibited an excellent flame‐retardant efficacy on the coal, especially at the low temperature stage. CH3 and CH2 were reduced by 56.86% and 47.17% processed by deoxidization gel foam. Meanwhile, the significant reduction in the content of reductive functional groups indicated that the new inhibitor had a strong suppression capacity for coal spontaneous combustion. Based on above research, it is believed that this study will lay an important foundation in the widespread application of deoxidization gel foam technology for coal spontaneous combustion prevention in underground mines.

Research Progress of Gel Foam Extinguishing Agent in Coal Mines

“…It prevented the further oxidation of the coal structural group −OO and thus terminated the chain reaction of free radicals in the coal. Lu et al [67] incorporated sodium dithionite, calcium hydroxide, and activated carbon in a gel foam for a composite deoxygenation gel foam. It has an inhibitory effect on coal oxygen adsorption by blocking the coal radical chain reaction by reducing the alkyl, hydroxyl, and carbonyl groups of coal.…”

“…The results showed that the blocking effect of each particle size of the coal sample by gel foam was in the order of large particle size > medium particle size > small particle size. Lu et al [107] used a coal self-ignition signature gas determination experimental system and a simultaneous analyzer to test the coal warming rate, the development pattern of signature gas, and the characteristic temperature and thermal effect of coal during pyrolysis of coal samples treated with gel foam, respectively. It was found that the hindering performance of gel foam was better compared with waterbased foam and slurry.…”