A berth has been closed at a Vale bulker loading facility after a fire on Thursday.
The rest of the Ponta da Madeira terminal was operational, however, the Brazilian mining giant said.
A shiploader went ablaze early on 14 January at the main iron ore export facility in the North-east of the country, the company added.
High-grade Carajas ore is shipped out from Ponta da Madeira.
The blaze was later brought under control by firefighters, Vale said.
The miner gave no information on the extent of damage, or the potential impact on exports.
Cargo delays are expected, according to the Platts news agency.
One shipowner with a vessel loading there told the agency that the 4S shiploader had burned. This is mainly used by VLOCs.
Disruption ahead?
"Vale informs that an incident occurred in the early hours of this Thursday, January 14, in one of our ship loaders at the Ponta da Madeira Maritime Terminal, in Sao Luis, Maranhao," Vale said.
"The fire brigades and the fire department were activated and the fire contained, without any victims or environmental damage. The terminal continues to operate."
And Vale added: "The affected site will undergo an assessment. The causes of the incident are under investigation."
One shipbroker said a berth had already been closed there due to a recent collision. Three other berths are continuing as normal.
Iron ore prices rose on Thursday on supply concerns.
Prices could increase further due to potential disruption at Ponta da Madeira.
