Ivanhoe Mines has unveiled results of an independent preliminary economic assessment (PEA) at its Kamoa copper discovery in the Democratic Republic of Congo, which indicated that the project would cost about $1.4bn.
The assessment gave the asset a $4.3bn pre-tax net present value (NPV) at an 8% discount rate.
According to the PEA, the project would be developed into a large mine and smelter in two phases.
Phase one of mining would target high-grade copper mineralisation from shallow, underground resources to yield a high-value concentrate.
The second phase would feature a significant expansion of the mine and mill and construction of a smelter to produce blister copper.
Ivanhoe Mines said the PEA proposes the establishment of a conventional copper mine and concentrator complex at Kamoa with an initial mining rate and concentrator capacity of three million tonnes per year.
Initial mill feed would come from the Kansoko Sud mineralised zone and lead into the Centrale area of Kamoa's mineralized zones.
The concentrator, however, would be expanded by the fifth year, producing a further eight million tonnes a year (mtpa). An on-site smelter would be built to yield around 300,000t per year of blister copper.
The operation is also expected to produce about 1,600t of sulphuric acid per day as a by-product in the copper smelting process, which could be sold to copper-oxide mining operations on the Central African copperbelt that currently buy acid from Zambia or overseas.
The production scenario schedules 326 million tonnes to be mined and milled at an average copper grade of 3% copper over a 30-year mine life.
It includes 7.8 million tonnes of payable blister copper and 500,000t of payable copper in concentrate, in the initial concentrate phase over the life of the project.
Ivanhoe Mines founder and executive chairman Robert Friedland said Kamoa has the rare combination of a very high copper grade and very large tonnage, qualities that position it to become a substantial copper producer with one of the lowest cash costs anywhere in the world.
"This thorough, independent assessment gives us added confidence as we proceed with the planning of our next steps to advance Kamoa's development into a world-class copper mine," Friedland added.