The study pegs initial capital costs for the 4 million t/y open pit operation at $294 million, with sustaining capital of $196 million.
At an 8% discount rate, the after-tax net present value is $380 million and the internal rate of return is 41.8%.
The new study improves the after-tax payback period to 1.4 years from 3.6. It also features a lower life-of-mine head grade of 0.83% compared with 0.95%. The study used consensus copper prices of $3.80 per lb. in 2024, $3.95 per lb. in 2025 and $3.40 per lb. after that.
Cash costs per lb. of copper are expected to be $1.36 per lb. Over the first five years of mine life, when production is expected to be 35,000 tonnes per year (compared with the life of mine average of 27,000 tonnes), cash costs will be only $1.12 per lb.
Ero has started detailing engineering for the project, located in southern Para state, and early construction works could start in the first half of 2022, if the board gives its approval.
In a release, Ero CEO David Strang said he was excited by the results, and that the project was the latest example of the company creating value from its existing portfolio.
“We started the re-evaluation of Boa from the ground up, beginning with a complete review of the mineral resource calculations that identified significant upside opportunities on which to build a new vision for Boa,” he said. “By re-logging core, focusing our efforts on geologic modelling and optimizing the mine sequence, we were able to identify a superior mine plan capable of supporting a much larger operation by pulling forward high-grade mineralization in the production plan.”
Proven and probable reserves at Boa Esperanca total 43 million tonnes grading 0.83% copper for 356,600 tonnes copper.
The company also sees additional exploration potential at the project. In the near-term, it’s targeting the Gap zone, a target area within the pit shell that has seem limited drilling.
Aside from Boa Esperanca, Ero holds the producing MCSA copper complex in northeastern Bahia state, Brazil, and the NX Gold mining complex in Matto Grosso state.
(This article first appeared in the Canadian Mining Journal)
