Study on the Mechanism of Slow-Release Antioxidant Inhibitor in Inhibiting Coal Spontaneous Combustion

Abstract

In order to inhibit spontaneous combustion from the essential structure of coal, anthocyanin was grafted with hydrotalcite composite high-absorbent resin after molecular modification to prepare a slow-release antioxidant inhibitor. Differential scanning calorimeter (DSC) experiments were used to compare the inhibition effect of different ratios and addition amounts, and determined the optimal ratio as 1:6 and the optimal addition mass ratio as 5 wt%. The evolution characteristics of free radicals and active functional groups in the oxidation process of coal samples were studied by electron spin resonance (ESR) and Fourier transform infrared spectrometer (FTIR). It was found that the inhibitor reduced the concentration of free radicals in coal, slowed down the consumption of key active groups. The correlation values between five kinds of key active groups and heat flow intensity were calculated by grey correlation degree method, and it was found that C=O was the most critical group to determine the heat flow intensity in the process of coal spontaneous combustion (CSC). The improved KAS conversion method was applied to calculate the kinetic parameters, and the results indicated that the inhibited coal oxidation required higher energy. The analysis reveals that the H+ released by the slow-release antioxidant inhibitor reacts with the active functional groups in the coal structure, terminates the free radical chain reaction of the active functional groups in the coal, and achieves the purpose of inhibiting spontaneous combustion, revealing the mechanism of inhibiting CSC. The research results have important guiding significance and application value for the prevention of CSC.

Keywords: Coal spontaneous combustion, Slow-release antioxidant inhibitor, Correlation analysis, Kinetic analysis, Inhibition mechanism