Seventeen wagons of a goods train derailed next to Acornhoek Station in Mpumalanga on Sunday evening.
Rail traffic was diverted through Polokwane.
A team was at the scene of the accident yesterday attempting to establish the extent of the damage and the cause of the derailment.
Spoornet's national spokesman, Mike Asefouitz, said the 40-wagon train was derailed at about 6.25pm.
It was carrying magnetite, an iron ore, from Phalaborwa, in Limpopo, to Broodsnysplaas, between Klaserie and Acornhoek.
He said ore had been spilled and an environmental impact assessment was in progress.
"We hope to have cleared the cordoned-off area by tomorrow and then everything can return to normal," said Asefouitz.
He said people intending to use the passenger train that uses the line on which the derailment occurred should find out if a bus service had been provided from their nearest railway station as an alternative to rail transport.
Asefouitz would not confirm that this was the third time a train had been derailed in the area in five years.
Commuters who use Acornhoek, Cottondale, Mbumba, Rolle, Machayi, Areagh and Mkhuhlu railway stations have been affected because the passenger train is not able to reach them.