Phelps Dodge Corp. has announced that its copper concentrate leaching demonstration plant at Bagdad, Ariz., has been commissioned ahead of schedule and is operating at design capacity.

The Bagdad plant is the first commercial facility in the world to use pressure leaching to treat chalcopyrite concentrates. It represents a major step forward in copper-extraction technology, said Timothy R. Snider, president of Phelps Dodge Mining Co. The new technology should make it more economical to recover copper from chalcopyrite ores, which account for approximately 70 percent of the worlds known copper reserves.

The use of concentrate pressure leaching with solution extraction and electrowinning (SX/EW) technology provides an alternative to conventional smelting and refining for the production of copper cathode from chalcopyrite flotation concentrates. The new technology is being developed and commercialized under an agreement between Phelps Dodge and Placer Dome, Inc.

The process involves leaching chalcopyrite concentrates in a pressure leach vessel. The resulting copper-containing solutions are blended with lower-grade stockpile leach solutions and subsequently processed by solution extraction and electrowinning.

The plant received its first concentrate feed on March 20, 2003, and achieved design capacity within two weeks. We actually reached startup and commissioning a month ahead of schedule, Snider said. Copper recovery is averaging 98 percent. The next steps in development of this technology are to prove the reliability, operating maintainability, materials of construction and costs of the process over an extended period of operation.

Phelps Dodge is considering concentrate-leaching technology for several operations and future projects, including the development of large primary copper deposits at the Cerro Verde mine in Peru and the El Abra mine in Chile.