Strategic Minerals PLC (AIM:SML) said it extended its exploration licence at Redmoor in Cornwall for a further ten years until 2037.
A 25-year mining lease option also remains in place, said the miner.
In addition, recent rises in the price of tin and tungsten are likely to increase the internally estimated US$163mln NPV (8%) even with higher mining costs.
An application is in progress for a drilling programme targeting new tin prospects in the Redmoor West area to follow up on earlier trenching work.
"Tin continues to attract wider coverage both within and beyond the mining community and this has been reflected in the substantial tin price appreciation since SML took full ownership of the project," Peter Wale, an executive director of Strategic Minerals, said.
“On top of that, tungsten is also quietly edging up and is now approaching 8-year highs. There has been significant US oil and gas industry demand for tungsten.”