The incident is under investigation by Peoria County Sheriff's Office and the Occupational Safety and Health Administration, but no foul play is suspected.
A co-worker told WSWS Dierkes was working near one of the large melters in the main foundry melting area, when the accident occurred.
"He was taking a sample of iron for the met lab and apparently just tripped," he said. "He died instantly, but not all of him went in."
"Part of his body remained on the deck for the coroner to retrieve. It must have been ghastly for those folks that witnessed it and to wait for the coroner with half of their coworker lying on the floor."
According to Caterpillar's website, the Mapleton Foundry is one of the largest in the United States, and can melt up to 1,000 tons of iron each day.
More than 800 people are employed at the foundry, which transforms sand and metals into solid iron block castings.
"We are deeply saddened by the death of an employee who was involved in a serious incident at our Mapleton, Illinois, facility on June 2," a company spokesperson told the Journal Star.
"Our thoughts are with this employee's family, friends and colleagues. The safety of our employees, contractors and visitors is our top priority."
The father-of-three is survived by "his best friend and life partner" Jessica, and their three daughters Rilie Myrl, 12, Remie Jo, 5, and Tamzlinn Jean, 4, according to his obituary.
"He was a hard-working teddy bear of a man with calloused hands and a tender heart," it reads. "He would have done anything for anyone with no expectation of anything in return. He would have given a stranger the shirt from his back even though that may have been his last shirt."
"Most of all, he was a wonderful loving father to his daughters that he absolutely adored."
It is the second occupational fatality at the foundry in just seven months, according to OSHA; in December, 50-year-old Scott Adams stepped off a ladder before falling 20 feet to his death through a hole in the floor.