Influence of Sulfur Content on the Thermal Release Characteristics of Coal Oxidation and Its Mechanism

As a key resource in China’s energy system, coal’s spontaneous combustion characteristics are significantly affected by sulfur content. In order to study the heat release characteristics and influencing mechanisms of coal oxidation with different sulfur contents, the C600 microcalorimeter and Fourier transform infrared spectrometer were used to analyze the changes in heat flux, heat release acceleration, heat release, and evolution of active groups in sulfur containing coal within the range of 0–300°C. The semi quantitative structural parameters were used to quantitatively characterize the changes in the aliphatic parameter CH2/CH3, oxygen-containing functional group parameter “C,” and aromatic parameter AR. The research results show that during coal oxidation, the heat flux, heat release acceleration, and heat release rate show a trend of first increasing and then decreasing with the increase of sulfur content. They peak at a sulfur content of 5.3%, and the heat absorption rate increases by a factor of 0.5866 and the heat release rate increases by a factor of 1.94 compared to a sulfur content of 2.8%. As the sulfur content changes, CH2/CH3 and “C” first increase and then decrease, and AR first decreases and then increases, indicating that the reactivity of coal first increases and then decreases. This study provides important theoretical reference for the prevention and control of coal spontaneous combustion in sulfur-containing coal mining.