Rio Tinto has agreed to buy an 11.65% stake in Boyne Smelters Ltd (BSL), the owner and operator of the Boyne Island aluminium smelter in Gladstone, Australia, from Japanese trading house Mitsubishi Corporation.

Financial details of the acquisition remain undisclosed.

This deal is subject to standard conditions, including clearance of Australia's Foreign Investment Review Board.

The sale, due to close in the second half of 2024, forms part of Mitsubishi’s efforts to reshuffle its aluminium portfolio.

Upon completion of the deal, Mitsubishi will remain active in the aluminium business, including trading and investment in bauxite assets, reported Reuters citing a spokesperson.

Last month, Rio signed a deal to acquire a 2.46% stake in BSL from Sumitomo Chemical.

The two deals are expected to bolster Rio Tinto's ownership in BSL to 73.5%.

Rio Tinto has expressed its commitment to working with the remaining BSL joint venture partners and stakeholders on securing a competitive low-carbon future for the Gladstone operations.

Following the completion of the two deals, the BSL joint venture will include Rio Tinto with a majority stake of 73.5%, YKK Aluminium holding 9.5%, UACJ Australia with a 9.29% stake, and Southern Cross Aluminium having a 7.71% interest.

Operating since 1982, BSL is said to be Australia’s second-largest aluminium smelter.

Located at Boyne Island in Central Queensland, the smelter includes manufacturing carbon anodes in the carbon plant, aluminium production (smelting) in reduction lines, and casting of molten metal into aluminium products ready to ship.

The smelter is connected to the Queensland Alumina Limited Refinery, via a conveyor belt, for the alumina supply.