Sigma Lithium announced an increase in the estimated size of its deposits of the electric vehicle battery metal in Brazil, which the company said will allow it to further expand production levels in the future.

Sigma has raised the mineral resource estimates at the Grota do Cirilo project in the Brazilian state of Minas Gerais by 27%, it said in a statement. It will now become the world’s fourth-largest operating industrial pre-chemical lithium complex, with 109 million tons in resources, the Vancouver-based company said.

The announcement comes at a time when lithium producers around the world are reeling from a steep plunge in pricing. Chinese prices of lithium carbonate — a partly processed form of the metal — slumped more than 80% last year on over-supply and a slowdown in EV sales growth in Asia’s largest economy. Still, lithium’s longer-term demand outlook is expected to be supported by the accelerating shift away from fossil fuels.

Sigma last year announced it was assessing a number of proposals for some or part of its business, but a strategic review that was planned to finish by the end of 2023 has still not been concluded.

In an interview, Chief Executive Officer Ana Cabral-Gardner said that the price plunge has been exacerbated by a surge in lithium production from informal mines that raise questions about their social and environmental sustainability. Sigma is calling for increased traceability measures in the market that she says would support prices at a $15 000 per ton level.

The CEO declined to comment on the strategic review process. The company, controlled by Brazilian private equity fund A10 Investimentos, has said it attracted parties including battery producers and EV automakers looking to secure supply.

The increase in resources will underpin Sigma’s plan to eventually expand its Brazilian project to a capacity of 104,200 tons of lithium carbonate equivalent. The current annual output capacity is 36 700 t.