CONVENT — One of three iron ore storage domes at the Nucor Corp. plant in St. James Parish suffered a structural failure and collapsed Wednesday, just weeks before the plant was to start production after more than two years of construction.
The collapsed beige dome, which looked like a deflated balloon Wednesday afternoon at Nucor’s site along the Mississippi River, did not result in fires, explosions, release of hazardous materials or injuries, authorities said.
Company officials are investigating the cause of the collapse of the storage dome, which is at Nucor’s direct reduced iron plant, according to Katherine Miller, spokeswoman for the Charlotte, N.C., company.
The $750 million plant will use natural gas to convert iron ore pellets into direct reduced iron once in production.
DRI is a basic building block used in Nucor’s electric arc furnaces to make steel, according to state air permit requests.
“The impact the collapse of the storage dome may have on the startup date for the DRI plant will not be known until the extent of the damage can be assessed,” she said in a statement.
The reduced iron plant is the first of several phases in a planned $3.4 billion steel complex that would employ 1,250 people.
Three iron ore storage domes sit in a row on Nucor’s 4,000-acre site. A conveyor system is connected to the tops of each dome. The part of the conveyor over the deflated dome was bent Wednesday, creating a kink in the connection between the other two domes and parts of the plant closer to the river.
The iron ore is delivered by ship and unloaded with a conveyor system, air permit requests say.
Before the collapse Wednesday, the DRI plant was undergoing “hot commissioning,” which is a series of trial runs ahead of the planned startup, company officials have said.
Plant manager Lester Hart said construction and hot commissioning continues despite the collapse.
“We are still continuing the construction, but we just don’t know if or what impact this will have on our startup,” he said.
He said it was too soon to say what effect the damaged conveyor system might have on plant operations.
St. James Parish officials said in a statement they received a 911 call of “an explosion” at the plant at 3:15 p.m. Wednesday.
Firefighters from Paulina and Convent and other emergency response agencies rushed to the scene but were recalled once officials realized a structural failure had occurred, according to Eric Deroche, parish director of homeland security and emergency preparedness.
The domes are made of concrete but have a fabric skin and contain iron ore, which is not a hazardous material, he said.
Workers could be seen leaving the plant Wednesday afternoon as emergency vehicles and fire trucks drove off after getting an all clear signal.
St. James Parish Sheriff Willy Martin speculated the collapse may have sounded like an explosion, leading to the initial 911 call and early news accounts of an explosion.
Some residents living near the plant along River Road said they were not aware of the problems at the plant Wednesday and had not heard anything.
Once in full operation, the DRI plant will produce 2.5 million tons of direct reduced iron per year, making it the largest DRI plant of its kind in the world and the first operating in the nation in several years.
Low natural gas prices played a role in Nucor’s use of DRI technology.
The DRI plant, which officials broke ground on in early March 2011, is the first of five phases that Nucor may build to create a $3.4 billion integrated steel mill in Convent.
Nucor officials had said Wednesday, before the collapse, that after startup in “the next few weeks,” production would ramp up during the fourth quarter of 2013 and that the DRI plant would be fully operational by the start of the year.
The company has already hired 140 people to work in the DRI plant and aimed to reach its planned 150-employee mark a year ahead of a 2015 goal, company officials said.