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Description:
Morenci is an open-pit copper mining complex that has been in continuous operation since 1939 and previously was mined through underground workings.

Did you know?
The Morenci mill expansion project, which achieved full rates in second-quarter 2015, expanded mill capacity from 50,000 metric tons of ore per day to approximately 115,000 metric tons of ore per day, which results in incremental annual production of approximately 225 million pounds of copper and an improvement of Morenci’s cost structure.

Location:
Greenlee County, Arizona, approximately 50 miles northeast of Safford on U.S. Highway 191.

Ores:
The Morenci mile is a porphyry copper deposit that has oxide, secondary sulfide mineralization, and primary sulfide mineralization. The predominant oxide copper mineral is chrysocolla. Chalcocite is the most important secondary copper sulfide mineral and chalcopyrite the dominant primary copper sulfide.

Processes and facilities:
The Morenci operation consists of two concentrators capable of milling 115,000 metric tons of ore per day (mtd), which produce copper and molybdenum concentrate; a 68,000 mtd, crushed-ore leach pad and stacking system; a low-grade run-of-mine (ROM) leaching system; four SX plants; and three EW tank houses that produce copper cathode. Total EW tank house capacity is approximately 900 million pounds of copper per year. Morenci’s available mining fleet consists of one hundred and twenty-six 236-metric ton haul trucks loaded by 13 shovels with bucket sizes ranging from 47 to 57 cubic meters, which are capable of moving an average of 815,000 metric tons of materials per day.

Background:
Phelps Dodge & Company invested $50,000 in the property in 1881, marking a New York mercantile’s first venture into mining. Through acquisition, Phelps Dodge & Company consolidated all mining operations in the district by 1921.
Intially underground, Morenci transitioned to open-pit mining beginning in 1937. The operations nearly doubled its production capacity during World War II at the urging of the U.S. government to meet wartime needs. Morenci’s first SX/EW plant was commissioned in 1987. Once home to two smelters, the last smelter ceased operation in 1984. Both have been demolished and reclaimed.

Ownership:
72% – Freeport-McMoRan Inc. (undivided interest); 15% – Sumitomo Metal Mining Arizona Inc. (SMMAz is owned 80% by Sumitomo Metal Mining Co. Ltd. (SMM) and 20% by Sumitomo Corporation); and 13% – SMM Morenci Inc. (fully owned by SMM)