hi,
The only instance I can recall is when coal is stored in very large heaps/piles.
You can get 'internal combustion' self heating of the pile, which if is hot enough can produce carbon monoxide, resulting from incomplete burning due to lack of oxygen in the piles core.
Old coal colliery waste tips can burn internally for years.
Mine fires are more frequent and ubiquitous than you hear about. They're the darkside of coal mining (you know, as oppose to the cheery notion of spending a life's work in the bowels of the planet), and burn for centuries, since they're impossible to put out.