Effect of Wet Carbonation of Calcium Carbide Slag on CO₂ Sequestration and the Prevention of Coal Spontaneous Combustion

Under the concept of integrated technology for coal mine disaster reduction and carbon dioxide (CO₂) emission reduction, this study investigates the effect and mechanism of CO₂ storage through the mineralization of calcium carbide slag (CS) while exploring the inhibition effect of the resulting products on the spontaneous combustion of coal. The effects of different water-solid ratios, pressures, and rotational speed conditions on the mineralization of CS were analyzed. The results showed that the CO₂ storage of carbide slag was positively correlated with pressure, and the carbonation efficiency was negatively correlated with pressure. With the increase of rotational speed, the amount of CO₂ trapped by solid waste increases first and then tends to be flat (the increase of the CO₂ trapped amount is small when the rotational speed is higher than 900 rpm). The amount of CO₂ trapped in the solid waste was positively correlated with the water-solid ratio. Scanning electron microscopy/energy-dispersive spectroscopy (SEM-EDS) was used to analyze the microstructure changes of solid waste and mineralized samples. It was found that the particle morphology before and after mineralization produced many irregular calcium carbonate particles, and ESD results exhibited that the carbon content increased significantly. Moreover, it was found by gas chromatography that the CO production of the coal sample treated with carbide slag slurry decreased to varying degrees, which indicated the inhibition effect of mineralized products on natural coal processes, that the product after adding reinforced waste mineralized CO₂ had a certain inhibitory effect on the coal oxidation reaction, further providing a theoretical basis for exploring the collaborative utilization of solid waste and carbon resources in coal mines.