The man was fully submerged in the 10 percent to 12 percent sulfuric acid solution as his Michigan Seamless Tube co-workers worked desperately to pull him from the industrial container, burning themselves from the at least 160-degree chemical solution, Fire Chief Robert Vogel said.
"Other employees, co-workers saw him in the tank," Vogel said. "He was completely submerged and was 100 percent covered in burns. The gentleman was trying to get out. They ran and grabbed him and pulled him out."
Roughly 11 hours later, the man died of chemical burns at 11:30 p.m. Saturday, said Kristin LaMaire, administrative assistant to the Washtenaw County Medical Examiner.
The employees had put the man under a safety shower, and medics then transported him to the University Hospital in Ann Arbor.
"He was speaking when we were there," Vogel said. "He was walking and talking. Unfortunately, he passed. It was pretty extreme burns."
It was unclear how he ended up in the vat and how long it was before he was rescued, he said.
The co-workers who assisted Hill sustained burns to their hands, Vogel said. Medics treated them at the scene.
The company is conducting a comprehensive investigation and is "cooperating fully" with the Michigan Occupational Health and Safety Administration investigation, according to a spokesman.
One of South Lyon's largest employers, the company has had seven workplace safety violations since 2012, according to OSHA, with fines totaling $93,000.
The state of Michigan fined the company $17,500 for a repeated violation in August of not guarding or protecting six employees from "pinch points," places where people or body parts could be caught in a machine or between equipment.
Regulators also determined 18 employees did not receive training on hazardous energy sources, resulting in another $2,500 fine.