The accident happened yesterday when 23 workers were dismantling a settling tank in the Henan branch of the Aluminium Corporation of China, officials said.
In addition to the 11 dead, another eight were injured.
Two of them are still in critical condition.
Kong Nianlin, one of the survivors, said as he fell his safety belt caught something on the wall, state-run Xinhua news agency reported.
He said many of his co-workers were not wearing safety attire at the time of accident.
Two massive explosions in the port of Tianjin, northern China, killed 173 people, left hundreds more injured and devastated large areas of the city in September last year.