TORONTO (miningweekly.com) – Canadian copper junior Curis Resources on Wednesday said it had completed a “positive” prefeasibility study (PFS) on its central Arizona property, which placed a pretax net present value (NPV) of $748-million on the project, at a 7.5% discount rate.

Authored by consultants M3 Engineering & Technology, the base-case economics for the flagship Florence copper project used a $2.75/lb long-term copper price and an average design production rate of 55-million pounds of copper a year in the first five years, rising to 85-million pounds in year six.

The base-case economics indicated an internal rate of return (IRR) of 38% and a pretax 2.4-year payback of the $129-million capital costs. This represented an 18% decrease from the initial capital cost estimate in the 2010 preliminary economic assessment. The commercial operating life of the project was also extended from 19 to 25 years.

At a price sensitivity of $3/lb of copper, the pretax NPV increased to $875-million and the project had an IRR of 41%.

The PFS found the mine could produce copper at a life-of-mine cost of 79c/lb.

The Vancouver-based company said operations would occur on land owned by and leased by Curis from the Arizona State Land Department (ASLD) for a total of 13 years.

The first nine years of copper production would occur exclusively on ASLD land and are scheduled to begin in 2016.  In the tenth year, production would expand on to private patented land owned by Curis.  

"With capital and operating costs that are estimated to be among the lowest in the global copper industry and a revised near term development plan now in place that provides a clear path to commercial operations, the PFS demonstrates both the economic and technical viability of the Florence copper project,” Curis CEO Michael McPhie said in a statement.

Curis plans on extracting the copper using in-situ leaching, a process whereby it pumps a weak acid into the orebody through wells, which dissolves the metal, to be pumped back up to surface where Curis will treat the solution at the plant to produce copper cathode.

Curis is awaiting approval from the Environmental Protection Agency for an underground injection control (UIC) permit for the Phase 1 production test facility (PTF) at the Florence copper project. Once the UIC permit had been received, the company would initiate formal construction and operations of a Phase 1 PTF.

The company’s TSX-listed shares rose by 5.22% to C$1.21 apiece on Wednesday.