TRIMET Urges Brazil's CADE to Block Alcoa-South32 Deal, Citing 51.8% Alumina Share

TRIMET Aluminium SE has asked Brazil's competition regulator, the Administrative Council for Economic Defense (CADE), to block Alcoa's proposed acquisition of South32's alumina and bauxite assets, saying the deal would cut independent smelter-grade alumina suppliers in Brazil from three to two. alcircle reported the request on November 7, 2026.

TRIMET's Objections to the Alcoa-South32 Purchase

TRIMET is a family-owned European aluminium producer based in Essen, Germany, with 2,400 employees and more than one billion euros in annual sales, according to akta.pro company records. It makes foundry, wrought and special alloys and runs primary smelting and recycling operations in Germany and France.

The German producer proposed remedies including the sale of integrated bauxite-mining and alumina-refining assets in Brazil or Western Australia, changes to ownership links in Alumar and MRN, and greater transparency and independent monitoring of alumina price reporting. TRIMET said the combined entity could control approximately 51.8 per cent of Brazil's merchant alumina sales, leaving Glencore with the remaining 48.2 per cent. It estimated Alcoa and South32 would hold a combined 52.66 per cent share of the wider Western merchant alumina market, potentially reaching 61 per cent.

The transaction includes South32's interests in the Alumar alumina refinery and the Mineração Rio do Norte bauxite mine in Brazil, plus the Worsley alumina refinery in Western Australia. Alcoa's ownership of Alumar would rise to 90 per cent after the acquisition. TRIMET said the deal would remove South32 as an independent supplier and that Alcoa could redirect around 3 million tonnes of alumina currently sold by South32 to third-party customers toward its own smelters.

"For Brazilian nonintegrated smelters — and for any project to industrialise the supply chain — the Proposed Transaction would mean relying on only two foreign suppliers, one of which accounts for more than half of the available supply," TRIMET stated.

TRIMET said it depends entirely on third-party suppliers for the smelter-grade alumina its smelters need, buying from companies including Alcoa and South32 through long-term contracts and spot transactions linked to published indices, particularly the Platts Alumina Index. It warned that reduced merchant supply or higher benchmark prices could raise production costs and squeeze margins while benefiting vertically integrated producers. TRIMET also said the acquisition would give Alcoa control of 95 per cent of Western Australia's refining capacity, including Worsley, which it described as an independent source of pricing data from the port of Bunbury.

Rio Tinto's Stake in Alumar

TRIMET asked CADE to examine Rio Tinto's 10 per cent interest in Alumar and Alcoa's potential access to those volumes. It also requested information on the companies' Western Australian production capacity, output, third-party sales, spot transactions and price reporting, and evidence behind their claims about spare capacity and expansion projects.

What TRIMET Wants CADE to Do

TRIMET asked CADE to conduct an in-depth investigation rather than use its fast-track review process. It also requested that the authority calculate market shares based on alumina sold to third parties rather than total production, which includes volumes consumed internally by integrated producers.