Catching up on Arizona copper mining activity

Nyal Niemuth, who runs our Phoenix office, joined AZGS last year from the Dept. of Mines & Mineral Resources, where he'd been evaluating mining and mineral resources in Arizona for 30 years. He briefed us last week on developments at southern Arizona copper mines.

Freeport McMoRan's drilling program at Twin Buttes is winding down. Freeport is continuing to review historic drill holes and creating a detailed deposit model. Speculation is that when the mine reopens it will feed the Sierrita mill. In the Fiscal 2011 10Q report, Freeport reported:

In December 2009, we purchased the Twin Buttes copper mine, which ceased operations in 1994 and is adjacent to our Sierrita mine. The purchase provides significant synergies in the Sierrita minerals district, including the potential for expanded mining activities and access to material that can be used for Sierrita tailings and stockpile reclamation purposes. We are conducting drilling on the property and metallurgical studies to support a feasibility study expected to commence in 2012.

Grupo Mexico reports that mine life is being extended at Asarco’s Mission and Silver Bell mines. Mission’s copper production should increase. Grupo’s 2011 Q1 report says:

Asarco began a pre-feasibility study in February 2011 for the project to restart a molybdenum circuit at the Mission mine. The study is expected to be completed in May 2011. Also, the exploration and drilling program continues and the proven reserves at the different mines are expected to increase by the end of 2011.

The company's 2011 Q2 says:

The exploration program for the properties in Arizona continues as planned. Ore reserves at Silver Bell increased by 24 million tons, equivalent to 148 million pounds of copper, which represents approximately two additional years of cathode production. The pre-feasibility studies for the project to restart a molybdenum circuit at the Mission mine continue and are expected to be completed in 3Q11.

And from Grupo’s 2011 Q3 report on Asarco:

Capital expenditures for the first nine months of the year were US$59 million, 209% over the previous year, mainly attributable to maintenance projects at the smelter, refinery, and the replacement of mine equipment and for the expansion of operations in Mission and Ray [mines].