Modeling the relationship between the influencing factors and the multiple responses of coal-like materials using Taguchi-Gray correlation analysis for their utilization in gas seepage studies

Coal-like sampling obtained through compression molding is an important application of powder compression molding technology in mining engineering. To obtain ideal coal-like samples for the revelation of the seepage property of low-permeability soft coals, gas seepage studies, which utilized the Taguchi method, were performed on coal-like materials with different particle sizes, activated carbon weight, Portland cement weight, and forming pressure. The effect of a single factor on the fluid-solid coupling property of coal-like materials was analyzed. The results indicate that the permeability and axial stress curves that correlated with strain in the conventional triaxial tests can be divided into three clear phases, and that layered damage appears in all tested specimens. The stress-permeability relationship model of coal-like materials is proposed. The influence of process parameters on the strength and permeability of coal briquettes during gas seepage tests was experimentally investigated. The Taguchi method and gray correlation analysis were integrated to determine the best combination of input factors through the key indicator of the gray relational grade, which is required to satisfy multiple quality goals in gas seepage coal-like materials. The contribution percentage of the input factors to the outputs was determined using analysis of variance; it indicated that coal particle size was the prominent influencing parameter followed by activated carbon, forming pressure, and Portland cement.