What is the cause of explosion propagation in mines?

The correct answer is coal dust, as it plays a significant role in explosion propagation within mines, particularly in coal mining operations. Coal dust can become suspended in the air, and when it mixes with oxygen in a specific concentration, it forms an explosive mixture. If an ignition source is present—such as open flames, electrical sparks, or even hot surfaces—the dust can ignite and lead to a rapid explosion.

Coal dust explosions can escalate rapidly, creating a chain reaction where more dust is disturbed and ignited, leading to further combustion and pressure waves that can cause extensive damage and endanger lives. Effective control measures are necessary to manage coal dust in mining operations, including proper ventilation, dust suppression techniques, and regular monitoring.

While methane is also a gas that can result in explosions, it is typically the ignition source that interacts with coal dust that leads to significant propagation of explosive forces. Electric sparks have the potential to ignite methane or coal dust but are not in themselves a primary cause of explosion propagation on their own. Water vapor generally does not contribute to explosion propagation, as it typically acts as a suppressant.