The employee had reportedly begun his shift at 19:00 local time (10:00 GMT) on Monday.
However, he was not reported missing until the following morning.
Police say they searched the factory and within four hours found what they believed to be human remains.
“After searching together with plant workers, we spotted what appears to be fragments of human bone inside a vessel,” Mr Kawano said.
“We don’t know if these really are human bones or if they belong to the worker who went missing,” he said.
“But if these are the man’s bones, maybe the worker fell into the pot,” he said.
He added that they were investigating whether any workers had witnessed what had happened.
The employee had been working 5m (16ft) above a melting pot which he was…
