What preparatory work is necessary before unsealing a mine fire?

The option that involves preparation for fire gases to pass directly to the main return while heavily rocking dusting all entries outby the seals is essential before unsealing a mine fire. This approach ensures that any harmful gases produced during the fire are effectively directed away from areas where miners may be working, thus reducing the risk of exposure to toxic fumes.

Rocking dusting outby the seals helps to control dust and can also act as a barrier, limiting the spread of fire or smoke. Proper management of air flow is crucial, as it serves to create a safer atmosphere for rescue operations and other mining activities. The preparation also reflects the importance of ventilation in managing both fire and the air quality within the mine.

In contrast, destroying flammable materials or simply cooling the area might not address the immediate concern of gas management, and maintaining ventilation systems alone does not prepare the mine for the specific dynamics of dealing with a fire situation effectively.