Telephone: 520-682-2420 Fax: 520-682-2347

Address: 25000 W. Avra Valley Road, Marana, AZ 85653

Location:23 miles west of Interstate 10 on Avra Valley Road.

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.

Production Statistics:
Copper in SX-EW Cathode:
45.9 million lbs. (2012)
46.8 million lbs. (2011)

Management:

Mark Kalmi, General Manager
John Alden, Mine Engineering Manager
Devar Cluff, Safety Engineer
Nancy Johannesmeyer, Sr. Environmental Engineer
Brad Stonehouse, General Mine Supervisor.

Economic Impacts:

2012:
Wages, salaries and fringe benefits: $16.6 million
Property, severance and sales taxes: $5.4 million
Total materials and other spending (energy, fuel and supplies): $48.4 million

2011:
Wages, salaries and fringe benefits: $15.0 million
Property, severance and sales taxes: $4.7 million
Total materials and other spending (energy, fuel and supplies): $46.0 million

History:

1850 - Gold and silver exploration leads to discovery of high-grade copper mineralization suitable for direct shipment to the east coast or England.
1880 - Several prospects are developed as commercial ventures and small smelters are built.
1900 - The consolidation of underground mines begin. A concentrator is built and concentrates are shipped by railroad.
1910 - Mining operations cease due to poor economic conditions.
1915 - Asarco completes the purchase of consolidated mining companies in the area.
1946 - Asarco geologists begin reevaluation of the properties in the area.
1951 - Stripping begins for open-pit mining of El Tiro and Oxide pits.
1954 - Milling operations begin for sulfide copper and molybdenum.
1960 - Dump leaching of copper oxides and precipitation of copper begins at 10 tons per day (TPD).
1965 - An expansion of the precipitation plant increases copper production to 15 TPD.
1967 - Mill and secondary crusher expansion is completed. Mill throughput is increased to 10,500 TPD.
1978 - A feasibility study is made to build a 15 TPD SX/EW facility that would replace the precipitation plant.
1979 - A study is made of a 20 TPD SX/EW facility by adding on-stream leaching of mill tailings and high grade in-pit leaching.
1984 - Evaluation of the North Silver Bell property begins. Mine and mill operations suspended, leach-precipitation operations continue.
1988 - A drilling program started in North Silver Bell to redefine the ore body.
1989 - The BS&K property is purchased and a 30 TPD SX/EW facility is proposed.
1990 - A rubble leaching evaluation is completed and a 50 TPD SX/EW facility is approved by the Asarco Board of Directors. Authorization to proceed is dependent upon the receipt of applicable permits.
1992 - The Bureau of Land Management land trade is completed.
1994 - Permits are approved and the authorization to proceed with the SX/EW project is granted.
1995 - All construction contracts are awarded.
1996 - Silver Bell Mining, L.L.C. partnership is formed – 75% Asarco and 25% Mitsui. Mining operations begin in North Silver Bell in April. Construction of the new facilities begins in May.
1997 - Dump leach and copper precipitation operations are shutdown in April. Construction of new facilities is completed and cathode production begins in July.
1998 - The cathode production rate is increased to 55 TPD.
2003 - SX/EW plant improves efficiency and production increases to 65 TPD.
2007 - No. 2 dump project approved and production forecast is increased to 67 TPD.
2031 - Reserve life of Silver Bell Mine