Which of the following is a type of serious accident or high potential incident in coal mining?

The type of serious accident or high potential incident in coal mining highlighted in this question is the unplanned ignition of gas or dust. This situation poses significant risks to the safety of workers and the integrity of the mining operation.

In coal mining, gas emissions, particularly methane, and the accumulation of combustible dust are common hazards. An unplanned ignition can lead not only to catastrophic explosions but also to severe injuries or fatalities among workers. Therefore, such incidents are categorized as high potential due to their serious consequences and the need for stringent management measures to prevent them.

In contrast, the other options involve standard operational procedures that are preventative in nature and do not represent immediate serious risks. Routine safety inspections, regular equipment maintenance, and workplace training are all essential for ensuring ongoing safety in the mining environment, but they do not qualify as serious accidents or high potential incidents since they are proactive measures rather than unintended events.