Lithium minnow Birimian plunged yesterday amid investor disapproval of a pre-feasibility study into its Goulamina project in Mali.

West Africa-focused Birimian (ASX:BGS) plunged as much as 36 per cent to an intraday low of 26c after the study showed the project may be more expensive than expected. The shares closed down 12c at 29c.

The study found the project was economically and technically viable based on five development scenarios ranging from $US86.9 million ($110 million) to $US142 million.

That compared to a January scoping study which costed the project at $US83.4 million for a processing plant and associated project infrastructure.

Net present value fell between $US85.6 million and $US126.4 million — more if the mineral resource was higher.

An 18-month development period was tipped to start in mid-2019, with initial production expected in early 2021.

The project had an operational life of nine to 14 years — compared to a 13-year life flagged in the scoping study.

“The pre-feasibility study demonstrates that Goulamina is potentially a robust project, both technically and economically, based on the current Indicated Mineral Resource,” Birimian executive director and CEO Greg Walker said.

Birimian believes results from recent exploration work show resources may be greater than the study indicates.

“The recent shallow-hole drilling results delineating additional lithium-bearing pegmatite anomalies at Yando, Sabali and Danaya have highlighted the exploration potential of the project area,” Mr Walker said.

“The forthcoming drilling program on these targets may increase the Project’s Mineral Resource base, which in turn would redefine and enhance the preferred development strategy.

Timing of a definitive feasibility study would be determined following the results of the upcoming drilling program.

Earlier this year, Birimian’s shares were suspended after a new board kicked off an internal review into its activities.

The review uncovered $1.8 million in unpaid taxes in Australia and Mali and a raft of corporate governance, compliance and disclosure issues.

Since the lifting of the suspension in late August, Birimian has traded as high as 48c. The company has a market cap of $55 million.