Rio, Winning Consortium Simandou (WCS) and the Guinean government have incorporated La Compagnie du TransGuinéen (The TransGuinean Company) to further progress plans to co-develop the multi-purpose and multi-user infrastructure for the project.
Rio and WCS will each hold 42.5% of La Compagnie du TransGuinéen, while the government will have a 15% free-carried interest.
It comes after a framework agreement was signed in March.
The parties will now work on next steps including shareholding agreement, finalising cost estimates and funding, and securing all necessary approvals and other permits and agreements required to progress the co-development of infrastructures, which includes 600km of rail.
Rio Copper chief executive Bold Baatar, who also oversees Simandou, said the Simandou development would complement the company's Pilbara iron ore portfolio.
"It is also a very important moment for Guinea and for Guineans, for whom the project's southern infrastructure corridor has the potential to bring significant benefits for regional economic development by leveraging international project and ESG standards," he said.
WCS, a consortium of Singaporean company, Winning International Group (45%), Weiqiao Aluminium (35%) and United Mining Suppliers International (20%), holds 85% of Simandou North block 1-2.
Simandou South block 3-4 is 85%-held by Simfer Jersey, a JV between the Rio (53%) and Chinese consortium Chalco Iron Ore Holdings (47%).
The Guinea government holds a 15% free-carried interest in all four blocks.
"Our country remains open to all responsible and serious mining investment that will help support the sustainable development of our economy and, in turn, is committed to maintaining a stable and calm business climate," Djiba Diakité, chairman of the strategic committee of the Simandou project and minister director of the Office of the Presidency of the Republic said.
Blocks 3-4 alone could produce as much as 95 million tonnes per annum of high-grade iron ore.