The deceased were identified as Prince Kshatriya (33), a manager, and labourer Balram Chaudhary (31), a native of Madhya Pradesh.
Dahej Marine Police said the incident took place at swelter plant-3, when the two employees fell into a 'Dry Copper Concentrate Vessel' at the plant, located in Dahej Industrial Area here.
"Kshatriya went to the top of the vessel which has a considerable depth for inspection, but lost balance and fell inside the hollow beam," Sub-Inspector S B Sharma said.
Other workers pulled them out and rushed to a hospital in Bharuch, but both were declared dead on arrival there.
"We have lodged a case of accidental death and started further investigation," Sharma said.
The company said in a statement that an enquiry would be conducted into the incident.