When I was a kid I had a friend whose grandfather supposedly worked at one of those back in the day and the biggest threat was the possibility of a dust explosion. If I remember the story correctly he worked at the one in Hay Lakes and it exploded. The structure was blown to flinders and smithereens but miraculously nobody was killed.
Dust is a constant problem in grain elevators. Many wooden grain elevators were retrofitted with dust collectors to help control the problem.
Grain dust is definitely explosive. I am sure I once read, and I cannot find any reference to it, that grain elevators had a design and certain shape to vent an explosion upwards.