What is the principal danger while sealing mine fires?

The principal danger while sealing mine fires is the risk of a gas explosion. When a mine fire occurs, it can create a range of hazardous conditions, including the accumulation of flammable gases produced by combustion. These gases can include methane and other volatile compounds, which are highly explosive when ignited.

When sealing a mine fire, if these gases are not properly managed or if there's an ignition source present, there is a significant risk that an explosion could occur. Proper ventilation management and monitoring of gas levels are crucial to ensure safety during the sealing process, making gas explosion the primary concern over other potential hazards.

While fall of ground, inhalation of toxic gases, and electrical failure are significant dangers in mining operations, the direct and immediate threat posed by a gas explosion in the context of sealing mine fires elevates it to the principal danger in this specific situation. Addressing gas management and explosion risks is critical to the safety of personnel involved in sealing operations.