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The Los Filos mine consists of two open pit mines, Los Filos and Bermejal, an underground mine at Los Filos, and a second underground mine at Bermejal now in development.
Location of the Los Filos Mining Areas and Mineral Deposits
The Los Filos mine is located 230 km south of Mexico City and is accessible by paved roads and a private airstrip.
The Los Filos open pit operation began commercial production in 2008. Gold is recovered from crushed and run-of-mine ore via a conventional, low-cost heap leach and ADR (adsorption-desorption-recovery) process.
Mineral Resources and Mineral Reserves
As of December 31, 2017, the Los Filos mine's Measured and Indicated Mineral Resources total 380.6 Mt at 0.94 g/t containing 11.5 Moz gold and Inferred Mineral Resources of 240.5 Mt at 0.74 g/t containing 5.7 Moz gold as shown in the following table:
Los Filos Mineral Resources (Dec 31, 2017) 1-9
|Class||Tonnes (kt)||Gold grade (g/t)||Gold ounces (koz)|
|Measured & Indicated||380,602||0.94||11,459|
- Mineral resources are inclusive of mineral reserves and do not include dilution.
- Mineral resources that are not mineral reserves do not have demonstrated economic viability.
- Mineral resources are reported to a gold price of US$1,400/oz and a silver price of US$4.26/oz.
- Open pit Mineral resources are defined within pit shells that use variable mining and recovery estimates depending on the geometallurgical domain and whether mineralization is projected to report to crush–leach or is considered typical run-of-mine for processing requirements.
- Open pit Mineral resources are reported to variable gold cut-off grades: Los Filos Open Pit 0.198 g/t Au, Bermejal Open Pit of 0.179 g/t Au.
- Underground Mineral resources use a mining cost of US$84.78/t for Cut-and-Fill, process cost of US$6.75/t, and a process recovery of 80%.
- Mineral resources are reported to a gold cut-off grade: Los Filos Underground of 3.39 g/t Au; Bermejal Underground of 3.0 g/t Au.
- Tonnages are rounded to the nearest 1,000 tonnes, grades are rounded to two decimal places for Au, grades for Ag are rounded to two decimal places; rounding as required by reporting guidelines may result in apparent summation differences.
- Includes both oxide and sulphide mineralization.
The Proven and Probable Mineral Reserves total 61.4 Mt at 1.26 g/t containing 2.5 Moz Au, plus an additional 0.2 Moz Au in Probable leach pad inventory, as shown in the following table:
Los Filos Mineral Reserves (Dec 31, 2017)1-6
|Tonnes (kt)||Gold Grade (g/t)||Gold Ounces (koz)|
|Subtotal Proven and Probable||61,444||1.26||2,499|
|Probable Leach Pad Inventory||216|
|Total Proven and Probable||2,715|
- Mineral Reserves are based on Measured and Indicated Mineral Resources within pit designs and supported by a mine plan, featuring variable throughput rates (depending on the pit being mined), variable metallurgical recoveries (depending on geometallurgical domain), and cut-off optimization.
- Metal price assumption for gold was US$1,200/oz.
- Open Pit Mineral Reserves:
- Los Filos Open Pit includes the mineralization within the planned 4P pit extension. Bermejal Open Pit includes the mineralization within the planned Guadalupe pit extension.
- Los Filos Open Pit crush-leach ore is based on an operational 0.433 g/t Au cut-off grade; ROM ore is based on a variable 0.247 to 0.581 g/t Au operational cut-off grade that is determined by lithology. Los Filos Mineral Reserve is based on a 0.191 g/t Au cut-off grade. El Bermejal Open Pit crush-leach ore is based on an operational 0.395 g/t Au cut-off grade; ROM ore is based on a variable 0.257 to 0.368 g/t Au operational cut-off grade that is determined by lithology. Bermejal Open Pit Mineral Reserve is based on a 0.20 g/t Au cut-off grade.
- Process gold recoveries vary from 54% to 76% for crush-leach ore and from 30% to 64% for ROM ore at Los Filos Open Pit; recoveries at Bermejal Open Pit for crush-leach ore vary from 51% to 68 and from 42% to 58% for ROM ore. A 5% silver recovery is assumed from all geometallurgical domains.
- Underground Mineral Reserves:
- Are contained within stope designs that have a minimum horizontal continuity of 10 m, and minimum mining width of 3.5 m, and supported by a mine plan that features variable stope thicknesses depending on zone; and cut-off optimization.
- Are reported based on a cut-off grade of 3.77 g/t Au for stopes within 100 m of planned ramp and 4.44 g/t Au for stopes requiring development.
- Dilution is assigned an average of 14% at a 0 grade for Au and Ag.
- Mining recovery is variable, based on stope width and can range from 75% to 100%.
- Process gold recoveries are estimated at 80% for Los Filos Underground ore. A 5% silver recovery is assumed from all zones.
- Tonnage and grade measurements are in metric units. Contained gold and silver ounces are reported as troy ounces.
- Summation errors may be present due to rounding.
The year-end mineral reserves and mineral resources are derived from Los Filos Technical Report that was prepared under National Instrument 43-101 – Standards of Disclosure for Mineral Projects ("NI 43-101"). The Los Filos Technical Report was prepared for Leagold by Doug Reddy (Leagold, SVP Technical Services), Rodolfo Balderrama Neder (Administración Los Filos, S.A.P.I de C.V., a wholly-owned subsidiary of the Company, Mine Operations Manager), Paul Sterling (Consultant to Leagold) and Dr. Gilles Arseneau (Associate Consultant with SRK Consulting (Canada) Inc., and independent of the Company), each of whom is a Qualified Person as that term is defined in NI 43-101. The authors of the Los Filos Technical Report prepared or supervised the preparation of the technical information upon which this web page is based.