The Santa Elena mill during late-stage construction. (Photo courtesy of SilverCrest Mines)
The Santa Elena mill during late-stage construction. (Photo courtesy of SilverCrest Mines)

SilverCrest Mines reported in mid-June that commissioning of the new, 3,000-mt/d mill and processing plant at its Santa Elena silver-gold mine in Sonora, Mexico, was on track to achieve design capacity by early August. The new CCD/Merrill Crowe plant is the key element of a three-year program to transition Santa Elena from an open-pit, heap leach operation to underground mining. At full production, the plant will produce about 1.5 million oz/y of silver and 32,800 oz/y of gold.

The $100 million Santa Elena underground transition program included drilling, a pre-feasibility study, detailed engineering, construction of the new processing plant, and underground development. FLSmidth, the primary equipment supplier for the mill and processing plant, had representatives on site supporting the commissioning process.

Underground development was ongoing, with more than 4,500 m completed on ramping, ventilation and ore development on five levels. Approximately 53,000 mt of development ore had been mined, with 41,500 mt delivered to the leach pad and 11,500 mt grading 1.17 g/mt gold and 98 g/mt silver in the stockpile awaiting mill processing.

All underground production equipment purchased by SilverCrest (one long-hole drill and three LHDs) was on site. Stope production was scheduled to begin at the 575 level in July. SilverCrest personnel will carry out all underground production mining from stopes, while a contractor will continue to do all development work.

Underground close-spaced definition drilling was in progress to better define reserves for initial and longer-term stope production. Santa Elena’s diluted, recoverable, probable underground reserves currently stand at 3.9 million mt, grading 108.1 g/mt silver and 1.57 g/mt gold and containing 13.6 million oz of silver and 198,170 oz of gold. An additional 3.6 million mt of indicated and inferred resources contain an estimated 15.4 million oz of silver and 188,000 oz of gold.

SilverCrest was forecasting Santa Elena’s 2014 production at 3.3 million to 3.6 million silver equivalent oz. It will review its market production guidance for possible changes once mill commissioning is complete and underground production is fully under way.

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