JOHANNESBURG (miningweekly.com) ­– Geothermal lithium is probably the greenest lithium in the world, says Sibanye-Stillwater CEO Neal Froneman, who told this year’s DigiMine event at his University of the Witwatersrand (Wits) alma mater that his company is looking to potentially extracting geothermal lithium.

“It comes from quite deep in the earth’s crust and we are seriously looking at companies that have the technologies in that space where they are running geothermal plants and they are actually putting the lithium back underground.

“We’re looking at how we can extract that and that would be the greenest lithium in the world,” said Froneman in response to a question at the Wits Sibanye-Stillwater Digital Mining Laboratory event moderated by Professor Fred Cawood and covered by Mining Weekly.

Lithium is currently derived mostly from hard rock mines, or from brine deposits below the surface of dry lake beds.

But the environmental impact of these means of extraction are seen as being quite steep, which is why the extraction of lithium from geothermal waters has received considerable attention, with several companies reportedly exploring that option in regions known for high-lithium content in geothermal waters.

The method is seen as having a small environmental footprint compared with conventional methods.

Earlier this month, Sibanye-Stillwater became Finnish lithium mining company Keliber Oy’s largest shareholder, with a 27% stake.

Keliber has lithium deposits in Finland, which are among the most significant lithium-bearing areas in Europe.

The Finnish company is scheduled to start production in 2024 at a rate of about 15 000 t of battery-grade lithium hydroxide a year from lithium mines and a concentrator plant in Kaustinen, Kokkola and Kruunupyy, as well as a lithium hydroxide plant in Kokkola.

Johannesburg- and New York-listed Sibanye-Stillwater is also investing $490-million in a lithium/boron mining project in Nevada, US, in joint venture (JV) with Australia-listed ioneer.

The JV will develop the Rhyolite Ridge project, which is expected to produce an average of 20 600 t of lithium carbonate a year, converting in the fourth year of operation to 22 000 t/y of battery-grade lithium hydroxide and 174 000 t/y of boric acid over a 26-year mine life.

The all-in sustaining cost for the project is $2 510/t, placing it in the bottom of the global cost curve. An offtake agreement to supply lithium carbonate to a unit of South Korean battery maker Ecopro has been signed by ioneer.