Emergency services raced to Edinburgh Napier's Merchiston campus after a fire ripped through the basement area just after 10.30am. It is thought to have been caused by a piece of equipment overheating.
Although students managed to put out the blaze, embers got into the extraction system which caused a dust explosion, sparking a second fire.
Billy Webster, of the Scottish Fire and Rescue Service, said: "In 25 years as a firefighter I have never experienced a dust explosion. The fire damage was mainly confined to the extractor machine although there was considerable smoke damage on the first floor."
The university will re-open today.