The miner's Africa COO Mike Fraser will be the "primary representative" to SAEC as well as overseeing alumina and aluminium operations in Australia and South Africa.
He will also have responsibility for the Cerro Matoso ferronickel project in Colombia.
The current Australia COO Paul Harvey will be the chief for manganese in Australia and South Africa and the Cannington and Illawarra met coal mines in Australia.
South32 CEO Graham Kerr said the SAEC split was progressing well.
"We are well advanced in our planning for this important strategic initiative and will provide further updates as we finalise our new operating model, governance structures and redesign the SAEC business," he said.