Rio Tinto’s $US23.2 billion ($34.3 billion) African iron ore project has won final approval from the Guinean and Chinese governments, clearing the way for first production to begin within 18 months.

The long-awaited final approval for the Simandou iron ore project in Guinea came on the same day that Rio’s flagship Australian iron ore division confirmed that a train derailment had hampered exports in the three months to June 30.