ASX- and NYSE-listed Ero Copper this week published a maiden preliminary economic assessment (PEA) for its Furnas copper/gold project in Brazil, outlining a 24-year initial mine life and robust economics.

The Furnas project, located in the Carajás mineral province in Pará state, is being advanced under an earn-in agreement with Vale Base Metals, through which Ero can secure a 60% interest upon completion of prescribed work programmes.

The PEA, the first ever published for Furnas, contemplates a large-scale, long-life copper/gold operation with average annual production of about 108 000 t of copper equivalent over the first 15 years. This includes about 70 000 t/y of copper, 111 000 oz/y of gold and 532 000 oz/y of silver.

On a life-of-mine (LoM) basis, the project is expected to deliver more than 1.2-million tonnes of copper, together with about 2-million ounces of gold and nine-million ounces of silver. The updated mineral resource underpinning the study remains open at depth and along strike.

Using long-term price assumptions of $4.60/lb copper, $3 300/oz gold and $40/oz silver, the project generates an after-tax net present value (NPV), using an 8% discount, of $2-billion and an internal rate of return (IRR) of 27%. At higher price assumptions of $6.10/lb copper and $5 550/oz gold, the after-tax NPV more than doubles to $4.7-billion, with the IRR increasing to about 44%.

Initial capital expenditure is estimated at $1.3-billion, equating to a capital intensity of about $16 000/t of copper equivalent. LoM C1 cash costs are projected at around $0.30/lb of copper, supported by significant gold and silver by-product credits.

“The results of the PEA on Furnas, the first ever published on the project, reinforce what an exceptional asset it is," president and CEO Makko DeFilippo said.

“The PEA outlines a large-scale, long-life copper/gold operation with strong underlying economics, supported by low capital intensity, first quartile operating costs and an attractive IRR across a wide spectrum of commodity prices."

He added that the study was the culmination of multiple drilling campaigns and more than a decade of technical work, noting that the deposit remained open and offered further upside through exploration.

Ero is also evaluating opportunities to enhance value, including additional drilling, the potential addition of a magnetite recovery circuit to produce a high-grade magnetite concentrate, and a gravity pre-concentration stage aimed at improving gold recovery.