Excelsior Mining has announced positive results for a pre-feasibility study of its Gunnison in-situ copper mining project 65 miles southeast of Tucson, Arizona. The focus of the project is the North Star deposit, which currently hosts total measured and indicated mineral resources of 3.91 billion lb of copper in 683 million st grading 0.29% copper and inferred resources of 1.40 billion lb of copper in 338 million st grading 0.21% copper. Probable mineral reserves stand at 3.61 billion lb of copper in 632 million st grading 0.29% copper.
Drilling activity at the Gunnison copper project’s North Star deposit, reported to contain resources of 3.91 billion lb of copper in 683 million st grading 0.29% Cu and inferred resources of 1.40 billion lb of Cu in 338 million st grading 0.21% Cu. (Photo courtesy of Excelsior Mining)
Major components of the Gunnison project include a wellfield, with injection, recovery, observation, and perimeter wells and related infrastructure; an acid plant, including sulphur and sulphuric acid handling and a cogeneration plant; processing infrastructure, including a solvent extraction/electrowinning plant; water treatment facility and facility ponds; ancillary infrastructure, including electrical substation, administration/office buildings, and transmission lines; and rail infrastructure and rail-car storage.
The proposed project would produce 110 million lb/y of copper during its first 14 years of operation. Start-up capital is estimated at $284.74 million.
“Completion of a positive prefeasibility study is a significant de-risking event in Excelsior’s development, and we are very pleased with the results,” Excelsior Chairman Mark J. Morabito said. “The results surpass the robust economic potential indicated by the 2011 preliminary economic assessment and support copper extraction of the North Star deposit through in-situ recovery, with the potential to generate exceptional financial returns.
“With initial production expected to commence in Q4 2016, we are looking forward to beginning the next phase of development,” he said.
The mineral resource estimate for the North Star deposit is based on results from 88 drill holes totaling 129,272 ft. The estimate was prepared using a 0.05% total copper cut-off grade and was effective as of January 13.