Rio Tinto CEO Jakob Stausholm told the Financial Times on Wednesday that the company’s board has given the green light to the Simandou mining project in West Africa.

Stausholm said the company aims to commence iron ore production from the $20 billion development as early as 2025. “The board yesterday approved the largest mining project in the world,” Stausholm told the Financial Times.

Rio said in January it expects to begin infrastructure work on the massive Simandou iron ore project this year following almost three decades of setbacks and scandals.

Set to be the world’s largest and highest grade new iron ore mine, the project will add around 5% to global seaborne supply when it comes on line. It is a partnership between Rio Tinto, the Guinean government and at least seven other companies, including five from China.

The project has been the subject of prolonged negotiations due to its complex ownership structure, delays caused by legal disputes, Guinea’s political changes and construction challenges.

Rio Tinto plans to invest $6.2 billion in the mine, rail, and port project in the Republic of Guinea, in collaboration with other companies, including five from China.

However, final investment approval from Rio’s state-owned Chinese partners, including Chinalco and Baowu, is still pending.

Nonetheless, Stausholm expressed confidence that this approval would be granted soon.

In January, Baowu raised $1.4 billion from a bond issue in China intended to support the project, which entails the construction of a 552-kilometre rail line to transport high-grade iron ore from two new mines in the Simandou mountains — one to be constructed and operated by Rio Tinto — to a new deepwater port on Guinea’s Atlantic coast.

Rio Tinto holds two of four Simandou mining blocks as part of its Simfer joint venture with China’s Chalco Iron Ore Holdings (CIOH) and the government of Guinea. Rio Tinto holds a 53% stake, while CIOH holds the remainder.