NEW MADRID, Mo. -- Preliminary investigations indicate molten aluminum hitting water caused explosions that injured more than 30 employees at a Southeast Missouri aluminum plant, a federal agency said Wednesday.
The U.S. Department of Labor's Occupational Safety and Health Administration is investigating the explosions that occurred Tuesday at the Noranda Aluminum plant.
OSHA officials said preliminary findings suggest molten aluminum came into contact with water, causing the explosions.
OSHA said 33 workers were hurt, but Noranda spokesman John Parker said none of the injuries was critical. One worker was treated for smoke inhalation and 32 for eye and throat irritation, OSHA said. Some also had ringing in the ears.
A large plume of smoke after the explosions could be seen for miles, and a Southeast Missourian reporter on the scene Tuesday saw the metal service building's south wall was ripped apart by the blasts and holes were seen in other walls.
Parker said the explosions occurred in the caste house, where the company produces extrusion billet, a length of metal with a cylindrical shape. OSHA said much of that building appeared to be destroyed, though other buildings were undamaged.
"OSHA is on scene and will conduct a thorough investigation at Noranda Aluminum facility to see if any violations of safety procedures contributed to this tragic incident," David Keim, OSHA's assistant area director in St. Louis, said in a statement.
Rhonda Burke, with OSHA's St. Louis office, said the investigation could take up to six months to complete.
It will be the second investigation at the plant in a little over a month. OSHA opened an investigation June 30 after the company reported a worker suffered second- and third-degree burns. That investigation has not been completed, Burke said.
On Tuesday, Missouri State Highway Patrol spokesman Sgt. Clark Parrot confirmed five injuries and was on his way to the plant to check for further details.
Injuries appeared to be limited to dust irritation, smoke inhalation and noncritical abrasions, he said.
All affected employees were released from medical care, with many returning to work Tuesday, Christian wrote.
Air Evac was called in as a precaution, but no one had to be lifted out, Parrott said.
Noranda is involved in all aspects of the aluminum industry, including technology, smelting, fabricating and mining, according to company literature.
All of the company's primary aluminum production takes place at the New Madrid plant.