South32 will power its 40% share of production using 100% renewable energy.

"With the smelter benefitting from existing infrastructure, access to our own supply of alumina and long-term green energy sources, we expect our investment to deliver strong returns through the cycle," South32 CEO Graham Kerr said.

The facility is expected to return to production in the June quarter, with full capacity for the smelter's three potlines of 447,000 tonnes per annum to be achieved in the March 2023 quarter.

South32, which is expecting to invest about US$70 million in the restart, said, that once at full capacity, the smelter will lift the group's annualised aluminium production by 16%, or 179,000 tonnes, to 1.269 million tonnes.

"With this decision we continue to make substantial progress in reshaping our portfolio, increasing our exposure to the base metals required for the critical transition to a low-carbon future," Kerr said.

South32 noted that its energy requirements have been secured under long-term contracts - with the smelter in the second quartile of the global aluminium cost curve - and the alumina supply will be sourced from the co-located 3.5Mtpa capacity Brazil Alumina refinery, which South32 has a 36% share in.

The smelter, which is part of South32's Brazil Aluminium operations, has been on care and maintenance since 2015. Along with the smelter and refinery, South32 also has a 14.8% interest in the 18Mtpa Mineracao Rio do Norte bauxite mine, which is used to supply the operations.