Jacob Denn was working the night shift at Spectro Alloys in February when the furnace erupted, showering the Hastings man with hot metal. Denn, 20, suffered burns on his back, head and legs and was rushed to the burn center at Regions Hospital in St. Paul.

It was the sixth time an explosion has rocked the Rosemount plant since 1989, when the facility was bought by the Palen family of St. Paul. In 2008, an aluminum scrap shredder blew up, leaving a worker permanently disabled. In 1996, a similar furnace explosion spewed molten aluminum on two workers, critically injuring one.

In three of those explosions, Spectro was cited for safety violations that caused or contributed to the explosions, records show. The company also has been repeatedly cited for violating environmental regulations by state and federal regulators. Minnesota's Occupational Health and Safety Division continues to investigate the most recent explosion.

The company's failure to properly deal with hazardous waste led Dakota County officials to file criminal charges against Spectro in 2007. Spectro pleaded guilty to two misdemeanors and was fined $1,354. Federal officials also are considering civil or criminal charges against the company for more recent violations, records show.

Will Branning, a Dakota County commissioner whose district includes Spectro, said the company's repeated injuries and violations make him wonder what it will take to ensure compliance. Commissioners considered revoking Spectro's hazardous waste license in 2007, but decided not to take that step -- which would have forced Spectro to close -- after company officials said they'd make improvements, Branning said.

"I surely don't want to put a taxpaying industry out of business," Branning said. "I want them to clean up their act."

Spectro owner and Chief Executive Gregory Palen said his foundry company, which recycles aluminum, is inherently more dangerous than many other industries. He said his company has spent millions of dollars on plant improvements.

"Our record hasn't been perfect, but our commitment is very strong to safety and environmental issues," Palen said.

'A wake-up call'

Spectro, which sits on 15 acres in the Pine Bend area, shreds used aluminum and melts it down into ingots weighing as much as 1,100 pounds. The plant uses about 10 tons of chlorine per day to remove aluminum impurities, state records show. The process of shredding and heating the scrap also produces air emissions, which can be hazardous.

The company's worst incident happened in December 1989, when a worker was killed after he climbed on a moving conveyer belt to dislodge a scrap metal jam. His left arm got caught in the conveyor, and he was crushed. The state fined the company $8,256, finding Spectro failed to provide "a place of employment free of recognized hazards."

A year later, the state division fined the company nearly $1,100 after an explosion caused third-degree burns to a worker who wasn't wearing required protective clothing.

Spectro was fined $2,000 after a 1996 furnace blowout injured two workers. The state said Spectro failed to adopt procedures that would have prevented moisture from being introduced into a furnace full of molten metal, which caused the explosion.

Scott Dodge was an assistant mill operator in 2008 when an aluminum shredder exploded, putting him in a hospital for seven months with a severe head injury. State regulators fined the company $55,500 for inadequate venting of aluminum dust, a key factor in the explosion.

The accident damaged Dodge's memory and left him unable to read or hold a conversation, said his wife. Kay Dodge said her husband requires around-the-clock care. His medical treatment is covered by workers' compensation, but the family filed a personal injury suit against Spectro to recover lost income. Spectro has denied negligence allegations, and a trial is set for October, court records show.

"I would say we have had a number of accidents," Palen said. "Any accident is a wake-up call and points out a need for more training and diligence."

Spectro workers also have been injured in chemical mishaps. In 1995, a release of chlorine required the hospitalization of seven workers, who were treated for respiratory problems.

Since 2000, Spectro has been fined more than $300,000 by the U.S. Environmental Protection Agency for a variety of serious violations, including unsafe emission of dioxins, which can cause cancer. In a 2009 letter to the company, EPA investigators alleged that furnace temperatures exceeded acceptable limits more than 7,800 times in a three-year period. EPA investigators also noted hundreds of cases in which the plant failed to properly monitor its equipment.

Palen said the case is under negotiation, but he acknowledged the facility failed a few air quality tests. He said other alleged violations were due not to emission violations but to faulty monitoring equipment that has been repaired. He said some furnace explosions were due to employees who didn't follow proper procedures.

To address the EPA's concerns, Spectro has proposed spending $1.8 million on a "major upgrade" to its emission and dust control systems.

Jim Adams • 952-707-9996