Societe Miniere de Boke, which mines aluminum raw material bauxite in Guinea, signed agreements with the West African nation to spend $3 billion on a railway, an alumina refinery and the development of new mining areas.

The 135-kilometer (84-mile) railway, which will link mining operations to a river terminal, will cost an estimated $1.2 billion and is expected to start operations in 2022, the group said in a statement Monday. The refinery will have capacity of as much as 1 million tons a year and require $700 million to $900 million of investment.

Production from the new mining deposits is expected in 2022, with estimated output of 10 million tons in the first year, increasing to 30 million tons in 2024.

Guinea vies with Australia as the biggest exporter to China of bauxite, the raw material used to make alumina and eventually aluminum. SMB is a joint venture owned by Singapore’s Winning Shipping Ltd, China’s Shandong Weiqiao and logistics group UMS International. The government of Guinea also holds 10 percent.

China’s bauxite imports from Guinea will continue to increase in 2019 as new mines ramp up, Bloomberg Intelligence analysts Yi Zhu and Anthony Cham Fung Yau said in a Nov. 15 note. Guinea accounted for 40 percent of China’s bauxite imports of 68.6 million tons in 2017.