A 30,000 tonne per year battery grade lithium hydroxide plant would cost US$572 million with all-in sustaining lithium hydroxide production costs estimated to be around $10,630 a tonne, it said. 

The study assumed a fixed price of $22,000 a tonne for lithium hydroxide and $1,200 a tonne for spodumene concentrate. 

Piedmont has spodumene concentrate supply agreements with ASX-listed Sayona Mining and London-listed Atlantic Lithium. 

The assessment for the second plant demonstrated the potential for Piedmont to expand its lithium hydroxide manufacturing business, it said. 

The project would have a steady-state EBITDA of $346 million a year, an estimated net present value of approximately $2.25 billion and an internal rate of return of 33%. 

Development remains subject to final site selection and financing, it said.

The firm has previously been reportedly considering Canada as a potential site for a processing facility. 

The proposed second facility will process spodumene into lithium hydroxide rather than be an integrated mining operation. 

The firm reported a feasibility study for its main integrated Carolina Lithium project in North Carolina last December.

This is based on an initial capital expenditure of $988 million and was based on a long term reference price of $18,000 a tonne. 

But the project requires state, county and federal permits, including those on environmental criteria. Local opposition to the mine has reportedly been strong. 

Development of the mine has been expected next month but the scheme is delayed.