Effects of SDBS+CDEA compounded with surfactant on the dust suppression and explosion characteristics of a methane-coal dust explosion: macroscopic, mesoscopic and microscopic analyses

This study systematically investigated the effects of the compounded surfactant sodium dodecylbenzenesulfonate (SDBS) and coconut oil fatty acid diethanolamide (CDEA) on the explosion characteristics of methane-coal dust mixtures from macroscopic, mesoscopic, and microscopic perspectives. At the macroscopic level, the explosion overpressure suppression effect of SDBS + CDEA was determined through pipeline network explosion experiments, which revealed that SDBS + CDEA significantly reduced the peak overpressure of methane-coal dust explosions. When the SDBS + CDEA concentration was 0.5 % and the ultrafine water mist concentration was 205 g/m3, the explosion peak overpressure at monitoring point 7 decreased to 0.157 MPa, corresponding to a reduction of 76.8 %. At the mesoscopic level, analysis of the surface tension, contact angle, settling velocity, and SEM morphology of coal dust indicated that the optimal concentration of the surfactant was 0.5 %, at which point the compounded system formed a continuous and dense coating layer on the coal dust surface, significantly enhancing the liquid bridge effect and wettability. At the microscopic level, thermogravimetric and infrared spectroscopy analyses revealed that the thermal decomposition rate of coal dust treated with SDBS + CDEA decreased while the maximum heat flux density increased, clarifying the evolution of the chemical structure of coal dust before and after treatment. Finally, the explosion suppression mechanism of SDBS + CDEA is discussed, which can be summarized as a “physical-chemical dual pathway” involving the liquid bridge effect and free radical capture. This study provides a theoretical reference for coal dust explosion prevention and control as well as for the preparation of compounded dust suppressants.