About 10,000 gallons of ammonia liquor was spilled at the ArcelorMittal Burns Harbor steel mill during a fire and brief power outage Tuesday.
ArcelorMittal contained the spill and has been working to clean it up.
"Ammonia liquor is a liquid waste byproduct from the ammonia scrubbing operations associated with coke production," Indiana Department of Environmental Management Public Information Officer Barry Sneed said. "ArcelorMittal explained that the release resulted from the high voltage power interruption that caused a backup in the production line and an overflow of ammonia liquor onto the ground."
The Indiana Department of Environmental Management's Emergency Response Program visited the mill to oversee the company's response to the spill.
"The waste ammonia liquor was contained on-site, and spill cleanup was in progress," Sneed said. "On Feb. 7, ArcelorMittal advised that spill cleanup is ongoing, with two environmental response companies vacuuming up the liquid and placing it in four on-site frac tanks. They plan to work through the night. IDEM will continue to monitor the cleanup."
Exposure to high levels of ammonia can cause irritation, coughing and burns, but ammonia occurs naturally in the environment and does not bioaccumulate or last long, according to the Chemical Safety Facts website.
The "high voltage power interruption" at ArcelorMittal Burns Harbor Tuesday caused major flaring when the mill had to burn off excess coke oven gas that normally would have been burned in a blast furnace to make iron, a key part of the steelmaking process. An automated emergency flare system at the mill triggered the flaring that resulted in towering flames that could be seen from U.S. 12.
"It is being reported to IDEM that there was not a structural fire," Sneed said. "Reportedly there was an increase in gas build-up in the coke ovens due to the power interruption. The observed flames were the intentional flaring of this gas buildup."
A firefighter with the Porter Volunteer Fire Department became ill while working to control the flames and had to be taken to a hospital to be treated for heat exhaustion.
Porter Fire Department Assistant Chief Dan Branham said the firefighter was treated and released.
"He's OK now," he said.
ArcelorMittal spokeswoman Mary Beth Holdford said no employees or contractors suffered "significant injuries" and that the steelmaking plant restored operations within 12 hours.