The mine is west of Avra Valley, near Marana, northwest of Tucson.
Asarco provides the following information about the Silver Bell mine:
Operations: The mine operates four open-pits (North Silver Bell, El Tiro, West Oxide and East Oxide). All copper in these pits will be extracted from the ore utilizing either of two hydrometallurgical processes: dump leaching or rubblization. Approximately 50% of the ore will be mined and hauled to dumps for leaching. The remaining 50% will be rubblized. Rubblization is the process where material is drilled, blasted, and then leached in place. Each month 1,800,000 tons of ore and waste are mined, and 700,000 tons of ore is rubblized. The four open-pits and other plant facilities are situated on 19,000 acres. Mining affected areas of the facility total 3,900 acres.
Copper-bearing solutions from the dump leach and rubble areas are collected and pumped to the solvent extraction plant where the copper in solution is concentrated over 30 times before being pumped to the tank house. In the tank house, the copper is recovered from solution using the electrowinning process and plated on stainless steel starter sheets as high-purity cathodes. The current cathode production rate is 67 tons per day. Cathode copper produced in the solvent extraction / electrowinning (SX/EW) operation is sold to producers of copper rod, tubing and wire.
Product: Electrowon cathode copper
December 31, 2012 Employment:
Total: 175 employees; 138 hourly / 37 salaried.
Copper in SX-EW Cathode:
45.9 million lbs. (2012)
46.8 million lbs. (2011)