Molten Metal Explosion + Aluminium Dust = Fire

No one was injured when a small explosion and fire evacuated part of the Mercury Marine plant in Fond du Lac Tuesday, April 10 in the morning.

Firefighters say an explosion caused molten aluminum to shoot 25 feet to the ceiling, which ignited dust particles, which wound up getting sucked into the exhaust system.

The Fond du Lac Fire Department was able to contain the fire to a furnace and exhaust system inside the facility.

Part of the plant had to be evacuated while firefighters and plant employees put out the fire. The plant was expected to reopen after the exhaust system was checked out.

The explosion occurred at about 9:45 a.m. when employees poured alloy-melted molten aluminum. The explosion caused melted aluminum to shoot 25 feet to the ceiling and ignited fine dust particles, which then drafted into the exhaust system.

Employees were expected to be back in operations after further investigation of the exhaust system.

Mercury Marine spokesperson issued a press release at about 5 p.m. Tuesday stating the “explosion” was a “thermal discharge of molten aluminum.”

 “After the facility was determined safe, manufacturing operations resumed as normal,” Mercury spokesman wrote in an e-mail. “Operations in other departments and plants within Mercury Marine were not impacted by this incident. Per Mercury’s standard process, root-cause analysis will be conducted and appropriate preventative measures will be implemented.”


The APSB found the term "thermal discharge of molten aluminium" to be a first.