At its Brucutu iron ore mine in Minas Gerais, Vale said it had completed 100 million tonnes handled by autonomous trucks, leading to safety and environmental benefits.

"In five years with vehicles without an operator in the cab, there were no accidents caused by trucks, carbon emissions have been reduced and productivity has increased," it said.

Vale said Brucutu was the first mine in Brazil with 100% autonomous operation, with all 13 trucks circulating using the new technology from 2019.

It was carrying out tests on autonomous trucks in Carajas and also investing in autonomous drills.

"It is important to emphasise that the conversion of a mine to autonomous operation requires a significant investment, therefore, Vale is working on the feasibility analysis of all units to prioritise where improvements will be implemented," it said.

Out on the water, Vale said "air lubrication" had been installed in a 325,000t Guaibamax named Sea Victoria which was on its way to Brazil.

The technology by English company Silverstream produced air bubbles under the ship's hull to reduce friction with the water, reduce fuel consumption and consequently lower emissions.

Sea Victoria was the first ore carrier in the world to use this technology, Vale said, and conservative estimates pointed to a fuel reduction of 5-8%.

"If the test is successful, the technology could be replicated on the remainder of the contracted fleet dedicated to transporting the company's ore," Vale said.

In a separate pilot project, Vale recently announced the launch of the world's first ore carrier equipped with rotor sails, also built in China and scheduled to arrive in Brazil at the end of the month, which could further reduce emissions.

The miner last year said it was aiming for net zero emissions (scopes 1 and 2) in 2050 and to reduce scope 3 emissions by 15% by 2035.

Vale shares are trading near a multi-year high and the company is capitalised about US$120 billion.