To improve the prevention of spontaneous coal combustion, reduced iron powder and other ingredients should be added together to form an iron-based deoxidizing inhibitor, with the dual effect of oxygen consumption and inhibition. The oxygen consumption rate of the inhibitor was studied through experiments. According to the theory of coordination resistance, the coordination resistance of Fe³⁺ was studied via the density functional method. Subsequently, a comparative experiment of the effects on spontaneous coal combustion was conducted. The research shows that several kinds of common resistance agents that are added to the reduced iron powder can consume oxygen. However, the rate of oxygen consumption varies. Fe³⁺ produced by the reduced iron powder indicates a strong coordination resistance. When compared with traditional inhibitors of Mg²⁺, Fe³⁺ has a stronger inhibition effect on the N, P, and S reactive groups in coal. The overall inhibitory effect is better than that of traditional inhibitors, because of the increased oxygen consumption and the coordination resistance of Fe³⁺ on the basis of traditional inhibitors.

To achieve wide-temperature-range inhibition of coal spontaneous combustion and address the limitations of weakly acidified seepage-prevention oxygen-removal (GMA) inhibitors, which lack targeted suppression of radical chain reactions at mid-high temperatures, this study developed an optimized sodium lignosulfonate (SLS)-reinforced composite inhibitor. Composition was optimized via single-factor experiments, FTIR, and response surface methodology. Mechanisms were systematically investigated through oxygen consumption tests, thermogravimetric analysis (TGA), segmented oxidation kinetics, and density functional theory (DFT) calculations. Results indicate the system maintains a stable oxygen consumption capacity between 20 and 50 °C, reducing early-stage oxygen supply. TGA reveals characteristic temperatures T1–T5 increased from 80, 144, 187, 355, and 399 °C to 117, 153, 216, 397, and 453 °C, respectively. Compared to the SLS-free system, T4 and T5 further rose significantly, demonstrating enhanced high-temperature inhibition. Kinetic analysis confirms a substantial increase in apparent activation energy across the T1-pre, T1–T2, and T2–T3 stages. Furthermore, the burnout index (Df) and comprehensive combustion index (S) decreased by 25.45% and ~69%, respectively. DFT elucidates that SLS phenolic hydroxyl groups act as primary active sites, engaging in reactions with key radicals (RCH2O·, RCH2OO·, and ·OH), specifically exhibiting barrier-less hydrogen transfer for ·OH quenching. This composite achieves wide-temperature-range inhibition through the synergy of low-temperature oxygen management and mid-high-temperature radical scavenging.