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.

Management:

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

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

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

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.
2014 AR Silver Bell purchases the 25% stake in Silver Bell LLC from Mitsui & Co., Ltd.
2031 Reserve life of Silver Bell Mine