The Sims Group is consulting over plans to close its Waste Electrical and Electronic Equipment unit at South Dock, which would see 99 posts go.
A 45-day consultation period began on 10 July.
The GMB union is consulting and said no final decision had been made, but changes in the market place meant the business was "commercially unattractive".
In June, Australia-based Sims Metal Management published outline details of a restructuring of its business in the UK and Canada.
It said the review "determined certain loss-making assets to be outside of the strategic long-term interests of the company".
A statement continued: "Legislation and market dynamics in the UK and Canada have resulted in these businesses being commercially unattractive to the company going forward".
The Sims Group is the world's largest publicly-listed recycler of both metals and electronic materials.
A nearby fridge recycling unit operated by Sims, which employs 35 staff, will be unaffected by the closure proposals.
Nearly 100 jobs are under threat at a recycling plant in Newport.