The agency said the upgraded outlook reflects the resilience of Gerdau's operations during 2016 and 1H17 despite Brazil's market downturn.
The US$2.5bn project has faced fierce opposition from environmental groups since it was submitted for approval in September 2013.
Chinalco's 2022 strategic plan includes autonomous trucks, automated CCTV and remote control of drills.
Peruvian miners are drilling again at properties across the country's Andean spine as surging metals prices provides an incentive.
The latest news from junior mining companies operating across Latin America.