It said it had signed an agreement with Vivo to implement a private 4G/LTE network in its operations in Brazil, which would optimise the use of autonomous equipment.

"Vale and Vivo will be the first companies to deploy a private LTE network with these characteristics in the country," the miner said.

Vivo would also provide 4G coverage, which would help communication among employees.

Vale uses private 4G/LTE networks in its operations in Canada and Malaysia but said in Latin America, the partnership model was only available in Chile, which was being tested.

"In addition to the benefits regarding data volume and coverage, the use of LTE is also an important investment due to it is scalability; all mobile phone technology development must comply with this standard from now on," Vale IT director Gustavo Vieira said.

The company said the network would be available from the first half of 2020 at the Carajás (Pará) mine, where three autonomous drills were already operating and autonomous trucks would "be adopted soon".

It said it would then be rolled out to the Brucutu mine, where 13 autonomous trucks operated and would migrate from a WiMax network to the new set-up.

"This network has the potential to be used to connect dam monitoring instruments," Vale said.

The company further trimmed its 2019 iron ore and pellets sales guidance this month to 307-312 million tonnes, with about 42Mtpa remaining suspended as the company continues its "gradual and safe return of operations" following the fatal dam collapse at Brumadinho in January.