The ruling, issued on Friday by Judge Antonio Lucio Tulio de Oliveira Barbosa, followed a civil lawsuit filed by the Federation of Quilombola Communities of Minas Gerais. The organisation argued that Sigma’s mining project falls within the direct area of influence of the Bau Quilombola Community, triggering additional legal protections and consultation requirements.
Quilombolas are traditional communities of African descent whose ancestors were largely people who escaped slavery and established settlements in Brazil. Their territories receive special protection under Brazilian law, particularly when large-scale developments such as mining projects could affect their land, livelihoods or way of life.
In his decision, Judge Barbosa said there was sufficient evidence to indicate that the Bau territory falls within the area of influence of the Grota do Cirilo project. That finding, he said, could require Sigma to comply with procedures including a free, prior and informed consultation with members of the community before continuing its activities.
The judge also expressed concern about the potential for physical harm and disruption to residents, pointing to what he described as "constant blasting and earthmoving activities just a few kilometres from the traditional territory."
The court cited studies placing the Quilombola territory approximately 2.7 km (1.7 miles) from the area directly affected by the mining project. That distance is significantly below an 8 km threshold identified in the proceedings as triggering a more extensive environmental and consultation process.
The ruling comes as Sigma Lithium maintains that its mining complex is outside the area considered to have an impact on the Bau community. The company’s position is now set to face further scrutiny as the court has ordered an independent georeferencing expert to establish the precise distance between the mining project and the Quilombola territory.
The suspension extends beyond Sigma’s existing environmental licences. The ruling also prevents the government of Minas Gerais state from issuing new environmental licences for the project while the dispute is being considered.
Sigma could additionally face financial penalties if it continues mining operations in defiance of the court order.
The development is significant for Sigma because Grota do Cirilo is the company's only productive asset. The mine has a nameplate capacity of approximately 330,000 tonnes of lithium oxide concentrate per year on an annualised basis.
The court case therefore creates a potentially significant operational setback for the lithium producer while raising broader questions about how mining companies operating near protected traditional territories must engage with local communities.
For the Bau community and the Federation of Quilombola Communities of Minas Gerais, the dispute centres on whether the project's proximity creates a legal obligation for consultation and enhanced environmental safeguards.
The independent georeferencing review ordered by the court is expected to provide a key piece of evidence in determining whether the mine falls within the legally relevant area of influence.
Sigma Lithium did not respond to a Reuters request for comment made outside normal working hours.