Excelsior Mining Corp. said its Gunnison copper project in Arizona is "fully permitted" after regulators gave it the all-clear after an appeals process was resolved.

The U.S Environmental Protection Agency lifted a stay on the operating permit that was in place during an appeals process Excelsior Mining settled in early October, the company said Oct. 16.

"There hasn't been a new copper mine permitted in the U.S. in over 10 years," JJ Jennex, Excelsior Mining's vice president of corporate affairs, told S&P Global Market Intelligence. "That's how rare this event is."

Jennex said Freeport-McMoRan Inc. was the last company to do so, with the Safford mine in Arizona.

In settling with critics of the project to end the appeals process, Excelsior agreed to additional monitoring wells at the Gunnison site, among other things.

Gunnison is proposed as an in situ recovery project. Wells would be drilled into the deposit and injected with a weak acid solution that reacts with the copper. The copper-bearing solution would be processed into copper cathode at the nearby Johnson Camp site.

Excelsior still requires funding to build the project. Jennex said he hopes that the company can announce a financing package by the end of October.

"Everything is on the table at this point, but we would like to avoid a large equity raise," Jennex said, noting that Excelsior is only looking to fund stage one of the project at this point.

The first stage would cost US$49.4 million to develop, with a 2016 feasibility study outlining plans to initially produce 25 million pounds of copper per year and ramp up to higher output under subsequent stages.

Gunnison hosts 782 million short tons grading 0.29% copper in probable reserves, representing 4.51 billion pounds of contained metal.