Development and performance study of a novel physicochemical composite inhibitor for the prevention of coal gangue spontaneous combustion

To overcome the short inhibition life of currently available inhibitors, a high polymer nanocomposite inhibitor was developed. The spontaneous combustion characteristics of coal gangue from the Yangquan mining area were studied through proximate analysis, scanning electron microscope/energy dispersive spectrometer (SEM/EDS), and thermogravimetric analysis. As a result, the coal gangue was found to be prone to spontaneous combustion. Temperature-programmed oxidation experiments showed that the average inhibition rates of Ca (OH)₂ or polyacrylamide (PAM) were 30.99% and 30.95%, respectively. During testing, when the temperature of the coal gangue exceeded 160°C, the CO production and oxygen consumption rate of the sample with PAM increased dramatically, proving that the PAM inhibition effect was short-lived with elevating temperature, whereas the inhibition rate of polyacrylamide/montmorillonite (PAM/MMT) was significantly increased to 47.70%. In addition, the CO production and oxygen consumption rates were significantly reduced in the late oxidation period, proving that the addition of MMT was able to effectively improve the high-temperature resistance of the PAM. Different concentrations of PAM/MMT were compounded with Ca (OH)₂, further improving the inhibition effect of the treatment. The inhibition effect of the PAM/MMT 3%-Ca (OH)₂ 20% composite inhibitor was the best in the study, with an inhibition rate of 83.15%.