Beyer has resigned and will leave the company on September 30 to pursue another opportunity in the resources sector.
The iron ore miner has promoted long-time chief financial officer Peter Kerr to CEO.
Kerr has been with the company since September 2012.
Tony Kiernan has been named as the new chairman of growing gold producer Saracen Mineral Holdings.
He will success Geoff Clifford, who will remain on the board.
Kiernan is also chairman of lithium producer Pilbara Minerals and copper-zinc developer Venturex Resources.
To coincide with his appointment to the Saracen board, Kiernan has stepped down as a director of Chalice Gold Mines.
South32 has promoted Simon Collins to the lead...