Juan Benavides, president of Chile’s state-owned copper miner Codelco, said on Wednesday that the company’s Chilean Chuquicamata underground mining copper mine will begin operations in the middle of this year.

Juan Benavides said that the underground mining operation is a basic step and a milestone for Codelco’s structural adjustment.

Codelco announced in 2018 that it will invest $5.55 billion to convert the world’s largest open-pit mining copper mine into a underground mining copper mine. This is part of a $39 billion, 10-year expansion of old copper mine capacity and maintaining high copper output.

The Chuquicamata copper mine has a history of mining for a century.

Chilean Finance Minister Felipe Larrain also confirmed on Wednesday that the copper mine will start mining underground.

Felipe Larrain said the Chilean government will pay the remaining $400 million in capital, after the Chilean government promised to provide $1 billion in funding for the company’s 10-year investment plan announced last June.

“This shows the government’s confidence in Codelco and the importance of Codelco’s ability to complete its structural reform program.”

The Chuquicamata copper mine and the nearby Radomiro Tomic copper mine produced 653,000 tons of copper last year.

Codelco’s copper output is about 10% of global output, and 1.818 tons of copper in 2018.