They MIGHT be trying to put out a fire in the existing coal seam still in the ground.

My only experiences with burning coal were my great grandparents coal burning potbelly stove, and a blacksmith forge in the little town where they lived. Lumps coal does not flame like that. Coal dust on the other hand is explosive under the right conditions.

From what I have have read and understand about coal, it can smolder for a long time, when it is being starved for oxygen, like in a coal seam under ground, or in the storage bunker on a ship. For example a blacksmith forge, the coal is recessed in a "bowl", the coal does not have good access to oxygen so it just smolders. But as soon as the bellows or blower feed air to it, the heat is intense.

A recent theory about the sinking of the Titanic involves a fire (smoldering) in a coal storage bunker before they even left port in Southampton. Supposedly, the ship was going so fast because the stokers were shoveling the coal into the boilers as fast as they could attempting to put out the fire.
https://www.smithsonianmag.com/smart...nic-180961699/