Name: Escobal mine.
Location: The Escobal mine is located in south-east Guatemala, about 40 km east-south-east of Guatemala City and 3 km east of the town of San Rafael Las Flores, in the Department of Santa Rosa.
Controlling Company: Tahoe Resources.
Brief History: Tahoe acquired the Escobal deposit from Goldcorp through a transaction completed in June 2010.
Based on the results of the preliminary economic assessment completed in 2010, Tahoe’s board of directors approved management’s recommendation to proceed to mine development and production. Underground development of the Escobal mine had started in May 2011, with the construction of the East Central and West Central decline portals, after which ramp development began. In October 2011, the Guatemala Ministry of Environment and Natural Resources approved Tahoe’s environmental-impact assessment for the design, construction, operation and closure of the Escobal mine. At that time, contractors were mobilised to start earthworks and the construction of the process plant and associated facilities in support of a 3 500 t/d mining and processing operation. Construction of the surface facilities continued in 2013.
The Escobal processing plant was commissioned in September 2013, producing its first concentrates later that same month. The operation declared commercial production in January 2014, with the plant reaching the 3 500 t/d design throughput rate in June 2014.
Brief Description: The Escobal deposit is an intermediate-sulphidation silver/gold/lead/zinc vein deposit. Tahoe Resources is operating at the initial design rate of 3 500 t/d and is preparing to increase the production rate to 4 500 t/d.
Geology/Mineralisation: The Escobal deposit is an intermediate-sulphidation fault-related vein system formed within tertiary sedimentary and volcanic rocks within the Caribbean tectonic plate. The Escobal vein system hosts silver, gold, lead and zinc, with an associated epithermal suite of elements, within quartz and quartz-carbonate veins.
Quartz veins and stockwork up to 50 m wide, with up to 10% sulphides, are at the core of the Escobal deposit and grade outward through silicification, quartz-sericite, argillic and propylitic alteration zones.
Drilling to date has identified continuous precious and base metal mineralisation at Escobal over 2 400 m laterally and 1 200 m vertically in the East, Central, West/Margarito and East Extension zones. The vein system is generally oriented generally east to west, with variable dips. The East and East Extension zones dip to the south from 60° to 75°, with recent drilling showing a change to a more vertical dip at depth. The majority of the mineralised structure(s) in the Central and Margarito zones dip from 60° to 75° to the north, steepening to near vertical at depth. The upper eastern portion of the Central zone dips 60° to 70° to the south as in the East zone.
Reserves: Total proven and probable reserves as at July 1, 2014, were 31.4-million tonnes grading 347 g/t silver, 0.33 g/t of gold, 0.74% of lead and 1.21 % of zinc.
Products: Lead and zinc concentrates.
Mining Method: Tahoe is mining the Escobal deposit using underground long-hole stoping methods, with processing by differential flotation to produce precious metal-rich lead and zinc concentrates.
Major Infrastructure and Equipment: The major mining equipment includes R1700 and R2900 Caterpillar load-haul dumpers, with 6 m3 and 8.3 m3buckets respectively, equipped for remote operation. A fleet of 45 t Caterpillar trucks are used for hauling ore and waste out of the mine.
Atlas Copco two-boom electric hydraulic jumbos are used to drive the development headings and stope development headings. Ground support is installed in all headings, with a fleet of Atlas Copco electric-hydraulic jumbos capable of installing split-set and swellex bolts. Cable bolting can be undertaken using Atlas Copco Simba drills or dedicated MacClean cable bolters; the Simba’s are also used in the primary production drill in the long-hole stopes.
The breaking slots in the stopes are drilled with Cubex track-mounted drills, each equipped with a V-30 reaming head. These drills are equipped with top hammers and can drill larger-diameter holes for utilities and production drilling where larger-diameter holes are desirable. Diamond drills are used for stope definition to enhance production planning before stope production.
The fresh-air intake in the East zone will be developed initially using a contractor. Caterpillar 120 AWD graders will be used for road maintenance in the mine.
Support equipment includes shotcrete remote spray jumbos and mixer trucks, scissor lifts, explosives trucks, and various materials handling vehicles.
Prospects: Tahoe expects mine and mill production to increase from 3 500 t/d in the first half of 2015 to 4 500 t/d in the second half of the year.
Contact Person: VP investor relations Ira M Gostin.
Contact Details:
Tahoe Resources
Tel +1 775 448 5800
Email investors@tahoeresourcesinc.com
Website http://www.tahoeresourcesinc.com