A Study on the Flame and Pressure Characteristics of Ultrafine Calcium Carbonate (CaCO3) Powder in Suppressing Gas Explosions

This study investigates the suppression effect of ultrafine CaCO3 powder on gas explosions through a series of experiments conducted in a medium-scale explosion tube (9.6 m in length) with varying concentrations of ultrafine CaCO3. The gas explosion suppression concentration was established at 9.5%. The results indicate that, at concentrations of 125 g/m3 and 300 g/m3, ultrafine CaCO3 powder significantly reduced the flame propagation speed of the gas explosion. Among the concentrations that did not fully suppress the gas explosion, 20 g/m3 effectively mitigated the flame propagation speed and overpressure throughout the entire process. The concentration of 75 g/m3 demonstrated a suppression–promotion–suppression–promotion pattern regarding the flame propagation rate, with significant fluctuations observed throughout the process. While the maximum suppression rate reached 60.9%, the maximum promotion rate was 131.12%. At 10 g/m3, the flame propagation rate initially increased before decreasing, with the most effective suppression observed within the first 6.6 m, where flame propagation suppression increased rapidly from 58.13% to 74.82%, and the peak explosion overpressure was reduced by up to 62.94%. These findings contribute valuable insights for the development of effective gas explosion suppression strategies in mining environments.