Resolution Copper, (RCM), is a joint venture owned by Rio Tinto and BHP, formed to develop and operate an underground copper mine near Superior, Arizona, U.S. The project targets a deep-seated porphyry copper deposit located under the now inactive Magma Mine. Rio Tinto has reported an inferred resource of 1.624 billion tonnes containing 1.47 per cent copper and 0.037 per cent molybdenum, at depths exceeding 1,300 metres (0.81 mi). This is one of the largest copper resources in North America.
The mining method planned to be used is block caving which creates subsidence. In an RCM report, subsidence is split into three categories collectively called "surface impact zones". These are intact zone, fracture zone and cave zone. The report indicates a substantial cave zone, for this project, with a long dimension of 11⁄2 miles and a depth exceeding 850 feet. The company is exploring solutions for tailings produced which will be on the order of 1.599 billion tones or 19.9 billion cubic feet. One possibility is using existing mined out open pits as tailing deposits. The company hopes to have the new mine in production by 2020. The proposed mine might be capable of producing 25 percent of projected future US copper demand for several decades.
The project is currently stalled pending a proposed land swap with the federal government. Resolution Copper has proposed to give the federal government 4,500 acres (18.2 km2) of environmentally sensitive land in Arizona in exchange for the 3,000-acre (12 km2) proposed mine site, which includes the popular Oak Flat Campground, which has been a protected area since 1955. In May 2009 Arizona Democratic representative Ann Kirkpatrick introduced legislation in Congress to complete the land swap. The swap already has the support of Arizona's two Republican senators. The swap also has considerable opposition and may have cost Ann Kirkpatrick her congressional seat.
The proposed land swap was readdressed during the 113th United States Congress when Rep. Paul A. Gosar (R, AZ-4) introduced the Southeast Arizona Land Exchange and Conservation Act of 2013 (H.R. 687; 113th Congress).
Resolution Copper has invested almost a billion dollars in the Superior project through 2012, and plans a $6 billion investment to develop the mine, if the Federal land exchange is approved. Pending approval, the project budget has been cut from about $200 million in 2012 to $50 million in 2013.
- Resolution Copper Mining LLC reports an Inferred Resource, 29 May 2008 news release
- Project Profile
- Resolution Copper: FAQs
- Niemuth, Nyal J. "Arizona". Mining Engineering. May 2008. p.71.
- LAND SWAP THREATENS OUR PUBLIC LANDS, OAK FLAT CAMPGROUND ON THE CHOPPING BLOCK, Arizona Sierra Club
- Erin Kelly and Dan Nowicki, Arizona Republic (21 May 2009): Bill revives land swap for Arizona copper mine, accessed 29 May 2009.
- "H.R. 687 - Summary". United States Congress. Retrieved 17 September 2013.
- "Letter to the community", November 30, 2012
- BUREAU OF LAND MANAGEMENT lead file AMC60069
- Sell, James D. "Porphyry Copper Deposits of the American Cordillera". "Arizona Geological Society Digest 20" 1995. p.373-395.
- Scott Manske & Alex Paul, Geology of a Major New Porphyry Copper Center in the Superior (Pioneer) District, Arizona. 2002, Economic Geology v. 97 no. 2 p. 197-220: Abstract. doi: 10.2113/gsecongeo.97.2.197