Rio Tinto has submitted an improved offer of $3.1 billion to acquire the nearly 49 percent of Turquoise shares it doesn’t already own.

Turquoise Hill previously rejected a $2.7 billion offer from Rio Tinto saying that offer did not reflect its full and fair value.

As part of the new offer, Turquoise’s minority shareholders will receive C$40 ($31) per share.

“Rio Tinto believes this offer not only provides full and fair value for Turquoise Hill shareholders but is in the best interests of all stakeholders as we work to move the Oyu Tolgoi project forward,” Rio Tinto Chief Executive Jakob Stausholm said in a statement.

Turquoise Hill is a single-asset company holding 66 percent of Oyu Tolgoi, one of the world’s largest known copper and gold deposits, 550 km (342 miles) south of Mongolia’s capital Ulaanbaatar.

Rio Tinto and the Mongolian government, which owns the remaining 34% of Oyu Tolgoi, earlier this year ended a long-running dispute over a nearly $7-billion expansion of the mine.

The improved proposal has the same conditions as its initial proposal, Rio Tinto said and is not subject to any financing condition or due diligence.

Rio Tinto controls and operates Oyu Tolgoi through its 51 percent stake in Turquoise Hill. The project is Rio Tinto’s main copper growth project.

The offers comes only two months after Rio Tinto and the government of Mongolia reached an agreement to complete the long-delayed $6.9 billion underground development of the Oyu Tolgoi project in the Gobi Desert.

That deal saw the Melbourne-based miner agree to write off $2.4 billion of loans and interest used by Ulan Bator to fund its share of the development costs.

First production from Oyu Tolgoi was initially expected in late 2020 but was rescheduled for October 2022 and later to the first half of 2023.

Once completed, the underground section will lift production from 125 kt –150 kt (138,000 to 165,000 st) in 2019 to 560 kt (617,000 st) at peak output, which is now expected by 2025 at the earliest.

According to the miner, this would make it the biggest new copper mine to come on stream in several years and, by 2030, the operation would be the world’s fourth largest copper mine.

Oyu Tolgoi is expected to produce 110 kt -150 kt (121,000 – 165,000 st) tonnes of copper and 4.5 t – 4.8 t (150,000-170,000 oz) of gold in concentrates in 2022 from processing ore from the openpit, underground and stockpiles.

Rio Tinto controls and operates the Oyu Tolgoi mine via Turquoise Hill’s 66 percent stake in the operation. The government of Mongolia owns the remaining 34 percent.