A pre-feasibility study conducted by Capstone Mining Corp. extended the mining life of the Pinto Valley copper mine in Arizona by eight years, the company announced.

Capstone Mining bought the mine in 2013 and now expects to be able to produce from the mine until 2026.

Average production for the first five years is expected to be 128.4 million lbs/year copper in concentrate and 6.6 million lbs of copper cathode.

Annual production for the life of the mine is 119.5 million lbs of copper in concentrate plus 6.3 million lbs of cathode copper.

The after-tax value, discounted at eight percent, is US$738-million while capital costs are estimated to be $187.9-million over roughly 12 years, The Canadian Press reported.

In April 2013, Capstone Mining announced it would buy the Pinto Valley mine and the associated San Manuel Arizona Railroad Co. in Arizona from a subsidiary of BHP Billiton for US$650-million.

The life of the mine, located in Arizona’s Globe-Miami mining district, about 125 km east of Phoenix, was initially expected to stretch until 2018.

“Completion of the (pre-feasibility study) ... provides us with the platform to stabilize operations, gain efficiencies and gives us the opportunity to take a longer-term view towards the future of the Pinto Valley mine,” said president and CEO Darren Pylot.

“As well as pursuing operating efficiencies, we have started the work required to evaluate a possible mine life extension beyond 2026 and a potential increase in throughput.”