Cochilco lowered its average copper price prediction for this year by $0.03 to $2.97 per pound on Thursday in its second negative projection in six months.
The company said the expansion, to start in early 2019, would add an average 60,000 tonnes of copper a year to its production over the first 15 years of operation.
China is the world's biggest consumer of the metal but its own copper mine production has been stagnating amid a broad crackdown on pollution, exacerbating a heavy reliance on imports.
Canada’s largest diversified miner has been looking for a development partner for the $4.8-billion extension of Quebrada Blanca copper mine in northern Chile.
Disruptions to cobalt supplies in the DRC are not expected to eradicate a glut of the material used to make batteries for electric vehicles, thwarting hopes that prices can be boosted from their lowest since March last year.
