Consol Glass (CSG) said 183 permanent jobs would be created by the plant and 36 young people from Duduza were being trained to be part of the workforce at the new plant.
But on Wednesday workers picketed the company´s plant in Pretoria, angered by reports that the company was spending money on expansion, while planning to retrench 32 workers at some of its operations.
One of the workers, who wished not to be named, said: "What disturbs us the most is that all the people who will be retrenched are black people and not even one white worker will lose his or her job."
Consol Glass confirmed that there was a restructuring process that could result in employees being given "the option of voluntary retrenchment".
But the company did not release figures of the people who would be affected by the restructuring.
"It is important to note that Consol is still in the consultation process, which has not yet been concluded.
"The process does include the option of voluntary retrenchment.
"In the interests of employee confidentiality Consol is not able to confirm details until such time as the consultation procedures have been concluded," marketing and communication manager Janine Loftie-Eaton said.
She said if the affected workers had the appropriate skills for vacancies at any one of the five Consol operations they would be considered.
"The retrenchments at CSG are site specific and the production demands for the plants are different.
"The business and staffing requirements for the Consol Nigel plant are different to that of the existing CSG production demands and staffing requirements," she said.
She dismissed the allegations that the retrenchments only focused on black people.
"At this point in the process, employees who have requested that they be considered for retrenchment come from all demographics.
"Management, in consultation with the union, will review the list," explained Loftie-Eaton.