What happens when coal dust is raised in clouds and ignited?

When coal dust is raised into clouds and ignited, it can indeed lead to a severe explosion. This phenomenon occurs due to the rapid combustion of the coal dust particles, which creates a significant increase in pressure and a shockwave that can result in an explosive force. The fine particles in the cloud provide a large surface area for combustion, allowing for a more efficient ignition process. The explosion potential is particularly dangerous in confined spaces, such as underground mines, where the accumulation of dust and limited ventilation can amplify the effects.

In contrast, the other options do not accurately represent the behavior of ignited coal dust. It does not disperse harmlessly; instead, the explosion can cause devastating damage and has been responsible for numerous accidents in mining operations. While coal dust may cool down after combustion, this would not be the primary concern during an explosion. Finally, while some combustion processes can convert solid fuel to gas, this is not the immediate consequence of an explosion when coal dust is ignited.