How can the explosibility of coal dust be reduced?

Reducing the explosibility of coal dust is crucial for maintaining safety in underground mining operations. One effective way to do this is by adding incombustible material to the coal dust. Incombustible materials do not burn and thus can dilute the concentration of combustible coal dust particles in the air. By increasing the proportion of incombustible materials, the overall combustibility of the dust mixture decreases, making it less likely to ignite or propagate an explosion.

This strategy is particularly effective in controlling dust in areas where coal dust accumulation poses a significant risk. The incorporation of materials like rock dust or gypsum can help create a safer environment by interrupting the chain reaction required for an explosion. This is a widely adopted practice in the industry as part of dust control measures.

The other options do not effectively address the explosibility of coal dust. Using lighter or finer particles could actually increase the risk of dispersion and suspension in the air, thereby raising the potential for explosive conditions. Conversely, increasing moisture levels can help control dust, but it does not necessarily reduce explosibility in a significant way as the moisture itself can influence how dust behaves in terms of ignition and combustion.