Tahoe Nears Full Production at Escobal
At the end of the third-quarter of 2013, 10 Escobal stopes were available for production, and an additional 10 stopes were in final development. Stockpiled mill feed totaled 97,250 mt at an estimated grade of 487 g/mt silver, 0.4 g/mt gold, 0.7% lead and 1.3% zinc.
All major plant components except the paste backfill plant were fully commissioned, and no impediments or bottlenecks to the 3,500-mt/d designed capacity had been identified. The paste plant was scheduled to be commissioned during the fourth quarter, when the first mined-out stope would be available for cemented backfill placement.
Mill optimization operations were under way to produce commercially viable metals concentrates to the specifications outlined in the Escobal project’s May 2012 preliminary economic assessment. This work was moving forward, and regular concentrate shipments to smelters had begun. As of mid-November, 891 mt of precious metal concentrates had been shipped from the mine site.
Improved tailings filtration will be critical to successful Escobal ramp-up. An abrasion-resistant filter cloth had been implemented, and optimizations of filter cycle times and thickener operation were under way. Operating parameters had fluctuated, as expected, during commissioning, and debottlenecking efforts had demonstrated continuous improvement.
Capital expenditures on the 3,500-mt/d Escobal project through mid-November totaled $317.9 million of the $326.6 million budget. An additional $35.8 million had been spent toward expansion to 4,500 mt/d.
Escobal is expected to produce 20 million silver equivalent oz/y over its first 10 years of operation at a total cash cost of less than $5/oz net of by-product credits.