The credits from the by-products production sees Piedmont potentially produce lithium hydroxide at a cash cost of US$3,112/t and lithium concentrate at $193/t, generating annual earnings (on an EBITDA basis), of $225-245 million.
The project is estimated to have a net present value of A$1.2 billion and an internal rate of return of 46%.
Piedmont is expected to need in the order US$109 million to get the show on the road in North Carolina, up $18 million on earlier scoping work that didn't incorporate the recovery of the by-products.
A second-stage development involving lithium hydroxide production being funded by cash flows.
The PFS is "targeted for completion in 2019".
Piedmont also said it would continue "ongoing discussions with potential strategic partners".
Piedmont started the current quarter with A$10 million cash.
Shares in Piedmont (PLL) were up 7% to 15c in morning trade, capitalising the company at $84 million.
The stock has spent much of the past 12 months trading in a range of 15-20c.
Piedmont last raised equity in October 2017 when $16 million worth of new shares were issued priced at 16c each.
