Brazil's National Mining Agency (ANM) has maintained the emergency level two rating for Xingu dam after a new inspection on Tuesday, sister publication Brazil Mining News reported.
Vale reiterated there was no imminent risk of rupture.
The company had stopped the trains on its Fabrica Nova branch at the Mariana complex earlier this month, in compliance with a notification from the regional labour superintendent, temporarily halting production at its Timbopeba plant with an impact of about 33,000 tonnes per day.
"After full implementation, the unmanned train will cover a 16km stretch using an integrated control system capable of automatically performing acceleration and dynamic braking operations," Vale said.
"It is expected that, at the end of the tests and implementation, which should take between one and two months, the Timbopeba plant will be able to keep its operation at around 80-100% of its daily capacity of 33,000t."
Vale said access for workers and vehicles to Xingu's flood zone remained suspended, including for the Alegria mine, with entry only allowed for people who worked in activities for the structure's stabilisation and in structuring actions for the deployment of the unmanned train through a strict safety protocol.
It has previously said the impact on Alegria would be about 7,500t/d.
Vale did not announce any change to its 2021 iron ore guidance of 315-335 million tonnes.
The company is aiming to build up towards 400Mt per annum as it overcomes restrictions put in place following the Brumadinho tailings dam failure in 2019 in Minas Gerais which killed 270 people.
