On January 31, 2011 a fatal flash fire at Hoeganaes Corporation fatally injured a one worker and seriously burned as another. The facility produces powdered iron and is located about twenty miles outside of Nashville, Tenn. Photo from U.S. Chemical Safety Board.
There’s a new update out this week from the U.S. Chemical Safety Board that shows again the dangers of combustible dust in the workplace:
The U.S. Chemical Safety Board (CSB) today released test results confirming preliminary conclusions that two flash fires which occurred at the Hoeganaes Corporation plant in Gallatin, Tennessee—one fatal—involved the combustion of iron powder which had accumulated throughout the facility and became airborne in combustible concentrations. A flash fire on January 31st killed one worker and seriously burned another. A similar fire occurred on March 29th and caused one injury.
According to CSB investigators:
The first incident occurred on January 31 as two maintenance mechanics on the overnight shift inspected a bucket elevator that had been reported to be malfunctioning due to a misaligned belt. The bucket elevator, located downstream of an annealing furnace, conveyed fine iron powder to storage bins. The two mechanics were standing alone on an elevated platform near the top of the bucket elevator, which had been shut down and was out of service until maintenance personnel could inspect it. When the bucket elevator was restarted the movement immediately lofted combustible iron dust into the air. The dust ignited and the flames engulfed the workers causing their injuries. A dust collector associated with the elevator was reported to have been out of service for the two days leading to the incident.
The second incident occurred less than two months later on March 29 when a plant engineer, who was replacing igniters on a furnace, was engulfed in combustible dust which ignited. In the course of the furnace work, he inadvertently dislodged iron dust which had accumulated on elevated surfaces near the furnace. He experienced serious burns and bruises as a result of this second event; a contractor witnessed the fireball but escaped without injury.
CSB Investigator-in-Charge Johnnie Banks said:
Tests conducted on samples of metal powder – collected from the plant – determined that this material is combustible.
The team observed significant quantities of metal dust on surfaces within close proximity to the incident locations. This was of particular concern as metal dust flash fires present a greater burn injury threat than flammable gas or vapor flash fires. Metal dust fires have the potential to radiate more heat and some metals burn at extremely high temperatures in comparison to other combustible materials.