Minimum explosive concentration of coal dust cloud in the coexistence of gas and coal dust

The present work was carried for the prevention of increasingly ever prevalent gas explosion accidents that had occurred in the coexistence of gas and coal dust in recent years. Using a 20 L explosion test system, we studied experimentally the explosive characteristics of the coexisting gas and coal dust and obtained the lower limit of gas explosion under different ignition energies, static and turbulent conditions and the lower limit concentration of coal dust explosion under different conditions. The results show that with the increase of gas concentration, the minimum explosive concentration of coal dust cloud decreases exponentially and that there is a critical gas concentration, in higher than which gas plays a leading role in the process of explosion, shown as the so-called "strong gas". Otherwise, coal dust plays the leading role, which is characterized by the "strong coal dust". The conclusions can serve as an important theoretical basis for preventing the coal mine gas and coal dust explosion.