Morenci Mine

Description: Morenci is an open-pit copper mining complex.

Did you know? We are engaged in a project to expand mining and milling capacity at Morenci to process additional sulfide ore identified through exploratory drilling. The project is targeting incremental annual copper production of approximately 225 million pounds in 2014 (an approximate 40 percent increase from 2013) through increases in milling rates to 115,000 metric tons per day (mtd).

Location: Southeast Arizona, about 50 miles northeast of Safford.

Ores: The Morenci mine is a porphyry copper deposit that has oxide and 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 includes a 50,000 mtd concentrator that produces copper and molybdenum concentrates; a 68,000 mtd crushed-ore leach pad and stacking system; a low-grade run-of-mine leaching system; four solution extract (SX) plants; and three electrowinning (EW) tank houses that produce copper cathode. Morenci also has a concentrate leach direct-electrowinning facility, which was commissioned in 2007 and processed copper concentrate until early 2009 when it was placed on care-and-maintenance status.

Background: Phelps Dodge & Company invested $50,000 in the property in 1881, marking the New York mercantile’s first venture into mining. Through acquisition, Phelps Dodge & Company consolidated all mining operations in the district by 1921. Initially underground, Morenci transitioned to open-pit mining beginning in 1937. The operation 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: 85% (undivided interest) FCX; 15% affiliates of Sumitomo Corporation.