The San Andres Mine is a heap leach operation with two stages of crushing. Mining at the San Andres Mine is currently carried out by an international contactor using conventional earth-moving equipment. Current production is approximately 4.9 million tonnes of ore per annum with an additional 2.4 million tonnes of waste moved annually.
The crushing circuit consists of a primary jaw crusher and secondary cone crushers, which reduces the ore size to a nominal 80% passing three inches for leaching. The ore is friable so a significant amount of fines is produced during the crushing stage. These fines are agglomerated using a combination of cement and lime. The crushed and agglomerated product is transferred to a series of conveyors to distribute the material on to the leach pads in 6 metre lifts for leaching. A conventional carbon absorption facility (ADR plant) is used to recover the gold from process solutions and produce a final gold doré product. The new primary crusher, conveyer and agglomerator facility and stacking system have been commissioned at the San Andres Mine. These capital projects have significantly reduced the ore haulage costs and improved efficiency of the system. During the first quarter of 2012, further steps have been taken to improve production at San Andres including replacing the primary crusher wobbler with a vibrating grizzly screen ahead of the jaw crusher to improve plant operating time, throughput and efficiency.