Evolution of pore structure and its influence on gas expansion energy for pulverized coal

The primary factor that determines the outburst hazard is the energy released by gas desorption. Previous studies have rarely quantified the initial gas expansion energy and have not adequately characterized the nonlinear adsorption process. To address these limitations, this study develops the FTGER model by introducing fractal geometry and time-varying diffusion parameters, enabling accurate calculation of gas expansion energy during outbursts. Based on N 2 (77K) adsorption and gas desorption experiments, we modified the model parameters and analyzed the pore evolution law, desorption volumes, and velocity characteristics. The results indicate that the proposed model effectively characterizes the gas expansion energy, which increases sharply by 12.77–14.21 times when coal particles are pulverized to the ultimate particle size, and quantitatively describes the evolution of desorption volume during the outburst process. The model further provides a basis for evaluating the outburst proneness of coal seams and shows applicability in both theoretical analysis and engineering practice. • Evolution of pore structure and its influence on gas expansion energy for pulverized coal. • ·Using experimentation to reveal the evolution of pore structure in the coal and gas outburst. • ·Establishing the FTGER model to quantify the gas expansion energy. • ·Analyzing the mechanism of outburst and refining the criteria for assessing outburst risk.