A recent explosion occurred in a single burner, recirculating solids ring dryer. The explosion caused significant damage to the dryer. All of the explosion panels opened, with two of the doors on the external ring duct were separated from their hinges, with one landing on the upper roof section, while the other fell back through the roof of the facility in the area of workers. The facility owners thought the accident was caused by a dust explosion, because they recently converted to a new process with finer solid particulates. However, process data also showed that the explosion could have been the result of a gas explosion. A computational fluids dynamic model was used to help evaluate the consequences associated with a dust or gas explosion during the incident. The simulated results showed that this was a gas explosion and not a dust explosion. Preventative recommendations are included. (C) 2010 American Institute of Chemical Engineers Process Saf Prog 29: 345-348, 2010