Abstract: The use of fly ash mineralized CO₂ material for preventing coal spontaneous combustion and storing CO₂ is a new path of resource utilization that balances environmental benefits and engineering application value. In response to the current problems of low self activity, and low CO₂ mineralization, and leaching of harmful elements in the utilization of fly ash, fly ash was taken as the research object. The microstructure and chemical composition of activated and mineralized products of fly ash under different excitation conditions (ball milling, water, NaOH, H₂SO₄, Na₂SO₄, and triethanolamine) and mineralization conditions (atmospheric pressure, 25 ℃ and 3.5 MPa, 150 ℃) were studied. The corresponding mechanisms of fly ash activation and mineralization were explored, and the CO₂ mineralization ability and harmful element leaching of fly ash under different conditions were quantitatively evaluated. And explored the inhibitory effect of raw fly ash and its different mineralized products on coal spontaneous combustion. The results show that during the activation process of fly ash, NaOH and H₂SO₄ can significantly change the chemical composition of fly ash. Among them, NaOH dissolves mullite by breaking the Al—O and Si—O bonds, achieving the release of Ca²⁺and providing a calcium source for mineralized CO₂. In the process of CO₂ mineralization in fly ash, NaOH stimulates the optimal amount of mineralized CO₂ in fly ash, reaching 82.37 g/kg and 67.19 g/kg at normal pressure and temperature, and high pressure and high temperature, respectively. Compared with the water excitation system, it increases by 196.83% and 112.86%, respectively. Triethanolamine may be used through its complexation to mineralize CO₂ at normal pressure and room temperature, and at high pressure and high temperature, with CO₂ concentrations of up to 55.74 g/kg and 55.47 g/kg, respectively. Compared with the water excitation system, this represents an increase of 100.86% and 73.68%, respectively. Simultaneously confirming that high pressure and high temperature are not absolute conditions for increasing CO₂ mineralization. The amount of harmful elements in the leachate of fly ash after different excitation methods and mineralization conditions is lower than the leaching toxicity identification standard value in the national standard. From the perspective of different mineralization conditions, compared to mineralizing CO₂ at normal pressure and 25 ℃, the release of Cr, Zn, and Hg elements from fly ash under various excitation systems significantly decreased after mineralizing CO₂ at 3.5 MPa and 150 ℃, while the As element significantly increased. From the perspective of different excitation methods, compared with the water excitation system, the NaOH, H₂SO₄, and triethanolamine excitation systems can significantly increase the release of harmful elements in fly ash. Additionally, preliminary studies confirm that the material formed by mineralizing CO₂ with fly ash primarily inhibits coal spontaneous combustion through physical inhibition mechanisms such as moisture absorption and coverage. Compared to raw coal, the crossing-point temperature of fly ash-treated inhibition coal samples shows an overall increasing trend, while oxygen consumption rates exhibit varying degrees of decline. Under 190℃ conditions, the oxygen consumption rates of all treated coal samples decrease by more than 34.48%. These findings provide a theoretical basis for the large-scale, green application of fly ash in disaster prevention and carbon sequestration.