San Manuel is a large, past-producing copper project in Pinal County, Arizona. It comprises two spatially separated but genetically related deposits, the San Manuel deposit and the Kalamazoo deposit, which together constitute one of the largest porphyry copper systems developed in North America. The exploration history of the project spans more than a century, progressing from initial prospecting in the late nineteenth century through systematic geological investigation and drilling programs that led to the definition of an economic copper resource in the 1940s and the discovery of the Kalamazoo deposit in the 1960s. The San Manuel project helped shape the region’s mining history and has contributed to the geological understanding of porphyry copper deposits worldwide, forming the basis for the Lowell-Guilbert porphyry copper model in the 1960s.
Commercial mining commenced in 1955 and continued until 1999. During its operating life, the San Manuel project was one of the largest underground copper mining operations in North America and was mined using a combination of underground block cave mining, open pit mining, heap leaching and in-situ leaching methods. Historical processing facilities included a concentrator, smelter, refinery, solvent extraction-electrowinning facilities and associated infrastructure. Historical production from the integrated San Manuel-Kalamazoo operation totaled over 4.2 million tonnes (4.65 million short tons) of copper together with significant molybdenum production and additional gold and silver by-products.
As a result of declining copper prices, mining operations at San Manuel concluded in 1999. A significant historical resource1 remained at closure, which is a historical estimate only and is not considered a current mineral resource or mineral reserve under NI 43-101. As part of the closure process, historical drill core was not preserved.
The project subsequently entered care and maintenance, and closure and reclamation activities were completed between 2003 and 2008 in accordance with approved regulatory closure plans. Major processing and smelting facilities were deconstructed and reclaimed, and the San Manuel project is currently subject to ongoing environmental monitoring and compliance activities. The project is not presently in production.
Today, the consolidation of the San Manuel project with the adjacent Copper Creek project into the Redhawk Copper Complex represents a rare opportunity to create a district-scale Arizona copper platform in one of the world’s premier copper jurisdictions.
San Manuel Project Highlights:
- Historically significant U.S. copper operation with approximately 44 years of production from the San Manuel and Kalamazoo deposits.
- Operating history includes major integrated mining complex with underground block cave, open pit, heap leach and in situ leach solvent extraction of copper and recovery by electrowinning (SX-EW).
- The discovery of Kalamazoo established the missing offset portion of the San Manuel porphyry system and helped shape the Lowell-Guilbert porphyry copper model.
- Extensive historical drilling, production, metallurgical, and operating data provide a strong foundation for modern technical evaluation and subsequent production.
- The combination of the San Manuel project with the Copper Creek project, now known as the Redhawk Copper Complex, creates a district-scale Arizona copper platform.