Australian mining giant Rio Tinto has moved to take full control of Canadian copper miner Turquoise Hill in a deal worth USD 4.85 billion, solidifying its grip on one of the largest known copper and gold deposits in the world.

Rio Tinto, which already owned a majority stake in Turquoise Hill, will buy the remaining 49 percent of the Canadian company for a total cost of USD 3.3 billion, giving the Australian heavyweight full ownership of a company that owns two-thirds of the Oyu Tolgoi mine in Mongolia.

The Oyu Tolgoi mine, which is part-owned by the Mongolian government, has had significant delays since construction began in 2019 and the estimated cost has increased from USD 5.3 billion to USD 6.9 billion.

Rio Tinto chief executive Jakob Stausholm said the deal will simplify governance and create greater certainty of funding for future of the Oyu Tolgoi project, which it currently operates.

The purchase price of C$43 per share is 19 per cent higher than the Canadian miner’s share price at last close, and Rio Tinto said the price is the company’s “best and final offer” after its previous offers to buy the company at C$34 per share were rejected.

The takeover has the unanimous approval of the Turquoise Hill board special committee but will need to be confirmed by a two-thirds majority of Turquoise Hill shareholders and a simple majority of votes cast by minority shareholders.

Shareholders are expected to meet to approve the takeover bid as early as the fourth quarter of 2022. If approved, Rio Tinto expects to finalise the takeover shortly thereafter.