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Mexico
Palmarejo Mine

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 Location:
66 km SE from Cholate, Chihuahua, Mexico

  Address:
Domicilio Conocido s/n
Chinipas de Aldama
Chihuahua, Mexico
33365
Phone635-457-2802
Fax635-457-7000
WebsiteWeb
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  • Overview
  • Owners
  • Geology
  • Mining
  • Processing
  • Production
  • Reserves
  • Costs & Financials
  • Fleet
  • Personnel
  • Filings & News

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Overview

StageProduction
Mine TypeUnderground
Commodities
  • Silver
  • Gold
Mining Method
  • Longhole open stoping
  • Transverse stoping
  • Avoca
  • Longitudinal stoping
  • Backfill
On-Site Camp yes
Mine Life8 years (as of Jan 1, 2021)
The Palmarejo complex consists of (1) the Palmarejo processing facility; (2) the Guadalupe underground mine, located about eight kilometers southeast of the Palmarejo mine; (3) the Independencia underground mine, located approximately 800 meters northeast of the Guadalupe underground mine, (4) the La Nación underground mine, located adjacent to the Independencia underground mine; and (5) other nearby deposits and exploration targets.


Owners

Source: p. 20
CompanyInterestOwnership
Coeur Mining, Inc. 100 % Indirect
Coeur Mexicana S.A. De C.V. (operator) 100 % Direct
The Palmarejo complex operated by wholly-owned subsidiary, Coeur Mexicana, S.A. de C.V.

Contractors



Deposit Type

  • Vein / narrow vein
  • Breccia pipe / Stockwork
  • Epithermal

Source: Source p.67-69,73,82

Summary:

Mineralization on the Palmarejo Complex consists of epithermal, low- to intermediate sulfidation, silver-gold vein and vein-breccia deposits that exhibit vertical and lateral zoning. The deposits occur within north-northwest-striking and west-northwest-striking structures (Sillitoe, 2010).

Silver and gold deposits in the Palmarejo Complex are characterized by pervasive silicification, quartz-fill expansion breccias, and sheeted veins. Multiple stages of mineralization produced several phases of silica, ranging from chalcedony to comb quartz, and two periods of silver-gold mineralization (Corbett, 2007). This strongly-zoned mineralization is characterized by pyrite, sphalerite, galena, and argentite (acanthite) deposited within the quartz vein/breccias at lower elevations and higher-grade preciousmetals mineralization with fine grained, black, silver-rich sulfide bands or breccia-infill in the upper portions of the structures. There is a general sense across the Palmarejo Complex that higher gold values occur deeper in the original mineral system, while richer silver values were deposited in the upper levels of these systems.

Mineralization at Palmarejo is hosted in northwest-striking and west-dipping structures that cut through a volcano-sedimentary sequence of reworked volcaniclastic, massive and pyroclastic deposits. The volcaniclastic rocks include ash-rich mudstones and sandstones. The massive rocks include microcrystalline massive basalt, fine grained massive andesite and plagioclase crystal-rich massive andesite. The pyroclastic unit includes tuffaceous sandstone, lapillistone tuff and dreccias (Galvan, 2007).

Palmarejo mineralization can be divided into three domains: the La Prieta and La Blanca vein domains, and the footwall and hangingwall stockwork domain developed along each of the two vein domains. The La Prieta vein domain consists of the La Prieta vein/breccia that dominated historic production from the area. The La Prieta footwall domain encompasses quartz stockwork mineralization and silicification within epiclastic rocks and andesitic tuffs. The La Prieta hangingwall domain consists of extensive sheeted-quartz-stockwork mineralization that is well exposed in the underground workings. The predominant geologic unit within this domain is an amygdaloidal andesite that lies between the La Prieta and La Blanca vein domains. The La Blanca vein domain consists of the La Blanca vein/breccia, which lies between porphyritic andesite on the hangingwall and amygdaloidal andesite and andesitic tuffs on the footwall. The La Blanca hangingwall domain includes quartz-stockwork mineralization within the porphyritic andesite.

The La Prieta structure extends for at least 3.5km, has a variable strike that averages about 115°, and dips to the southwest at 35° to 85°. The La Blanca structure strikes about 160°, has an average dip of about 50° to the southwest, and is thought to be a listric normal fault (Corbett, 2004) that parallels the trend of the regional faults in the SMO. Masterman et al. (2005) estimated up to 300m of throw on the La Blanca fault. Faults with similar orientations are the most commonly mineralized structures in the district.

A broad zone of mineralized quartz stockwork formed at the intersection of the La Blanca and La Prieta structures. North-trending splays from other north-northweststriking structures at Palmarejo may offset both the La Blanca and La Prieta faults (Beckton, 2004).

Gold-silver veins and vein/breccias occur within, and at the intersection of, the westnorthwest-striking La Prieta structure and the north-northwest-striking La Blanca structure. Multiple stages of hydrothermal activity and mineralization filled these structures with quartz veins and formed quartz stockwork mineralization within the wedge of rock formed by the intersection of the structures. Both the La Prieta and La Blanca veins have polymetallic silver-gold vein/breccias with an epithermal silver-gold overprint that forms high-grade shoots in the steeper-dipping portions of the listric normal faults (Corbett, 2004). Early mining focused on the La Prieta vein, where highgrade silver mineralization was present as bands of fine grained acanthite and galena within the vein.

Steeply plunging, high-grade ore-shoots, or clavos, have been identified in each of the vein structures. The Rosario and 76 Clavo contain the bulk of the mineralization at Palmarejo. The Rosario Clavo lies at the intersection of the La Blanca and La Prieta veins and is up to 30m wide. The 76 Clavo is a subvertically plunging shoot located at an inflection in the strike of the La Blanca structure. Clavo 76 terminates at depth as the structure flattens. 108 Clavo, also located on the La Blanca structure at its contact with silicified sandstone, is a gold-rich clavo. The Tucson and Chapotillo Clavos lie within the La Prieta structure.

Guadalupe Deposit
The Guadalupe deposit is approximately 7km southeast of Palmarejo and consists of two principal mineralized structures known as Guadalupe North and Guadalupe. The mineralized structures are located along a major northwesttrending (330°) structure that can be traced for approximately 3km along strike and has an average dip of approximately -55° to the northeast. Mapping by Stewart (2005) indicates both normal and strike-slip offset across the fault, with vertical displacement estimated to be at least a few hundred meters (Davies, 2007). Secondary westnorthwest- and north- northeast-trending structures have been identified by surface mapping in the Guadalupe area (Laurent, 2004; Davies, 2007). Outcrop expressions of the structure are dominantly characterized by essentially barren, moderately to pervasively clay-altered wall rocks and laterally discontinuous quartz veins, with thicknesses ranging from millimeters to a few meters. Beneath the clay-rich upper zone, the breccia veins are spatially associated with quartz-carbonate-pyrite-sericite- clayepidote-chlorite alteration in the wall rock.

The Guadalupe mineralized structures are hosted in a volcanic-sedimentary package that is intruded by shallow andesitic porphyries and a felsic dome complex. The silver-gold (± base metals) mineralization at Guadalupe occurs predominantly within northwest-trending, quartz-carbonate, breccia veins enveloped by variably developed quartz hydrothermal breccias and quartz-stockwork zones. These multiphase breccia veins range in thickness from less than a meter to greater than 20m. Subparallel veins, vein splays, and sigmodial loops of varying thicknesses are hosted in both the hangingwall and footwall blocks. Quartz stockwork zones are typically developed in the hangingwall blocks or between closely spaced subparallel quartz-carbonate-bearing structures.

Independencia Deposit
Silver and gold mineralization at Independencia is primarily controlled by a welldeveloped, northwest-striking structural zone that generally dips -60° to -70° to the northeast and straddles the concession boundary between Independencia Este (previously Paramount‘s Don Ese Project) and Independencia Oeste. The Mineral Resources for the deposit have been modeled over a strike length of approximately 1.3km with widths of up to 22m (average 6m) and a vertical extent of approximately 570m.


Mining Methods

  • Longhole open stoping
  • Transverse stoping
  • Avoca
  • Longitudinal stoping
  • Backfill

Source: p.220-235

Summary:

The Palmarejo gold-silver complex located in the state of Chihuahua, Mexico, consisting of the Palmarejo processing facility, the Guadalupe deposit, located roughly eight kilometers southeast of the Palmarejo deposit; the Independencia deposit, located approximately 800 meters northeast of the Guadalupe deposit; the La Nación deposit, located adjacent to the Independencia deposit, and other nearby deposits and exploration targets.

Currently Palmarejo complex is fed by the Guadalupe, Independencia and La Nación underground mines.

Guadalupe Underground Mine
The Guadalupe mine is located south of the Palmarejo processing facilities via an 8km gravel road.

Access to the Guadalupe mine is from surface via two ramps: the Poniente Decline and Oriente Incline, located 700m north of the deposit in the hangingwall. The decline serves as the primary access and exhaust airway, while the incline provides access for secondary egress, fresh air, and mine services.

Standard ground support consists of pattern rock bolting using 2.4m and 1.8m length 39mm diameter split set friction bolts, which are also used to pin 4 x 4 inch welded wire mesh to the back and ribs. The mesh is installed within 1.7m of the drift floor. A 1.4m x 1.4m bolting pattern is used, which is modified to a tighter pattern when poor ground conditions are encountered.

Underground mining is employed two general categories of open stoping methods: transverse and longitudinal. In most cases, thinner areas of the orebody (less than 10 meters from hangingwall to footwall) are mined using the longitudinal retreat method, while thicker areas are mined using the transverse method with a primary/secondary stoping sequence.

In thinner areas of the orebody, longitudinal stoping is carried out used the Avoca mining method. This method reduces the requirements for waste development and cemented backfill, which reduces overall mining costs. Stopes are sequenced in a retreat manner, from the end of the mining block towards the level access, in a bottom up mining direction.

Broken ore and development waste is mucked using a LHD loader. Some of the LHD units are fitted with remote controls, which are used for stope mucking where the machine and operator are exposed to unsupported ground.

The LHD loads trucks with ore or waste from either a muckbay stockpile, or directly from the stope or development face. The trucks have a rated capacity of 45-tonnes and some of the units are fitted with telescopic dump systems.

The trucks haul waste to surface, where it is disposed of outside of the portal in a waste dump or stockpiled for use as backfill. The ore material is dumped on the portal pad in a designated area, and then loaded onto surface trucks where it is hauled to the crusher ROM pad at the process plant area.

All stopes and ore development are backfilled.

Independencia Underground Mine
The Independencia deposit is located approximately 1,400m NE of the Guadalupe deposit. The entrance to the mine is via two portals located approximately 270m north of the Guadalupe mine portals.

The two declines provide access to the deposit and primary ventilation for the mine. The access ramps are designed at 5.5m high by 5.0m wide and are being driven at a negative gradient of -15%.

The Independencia deposit is mined with similar equipment, personnel and mining methods as the adjacent Guadalupe mine. The two operations also share some of the surface infrastructure, which has been constructed (or is planned) for the operations.


Crushing and Grinding
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Processing

  • Smelting
  • Flotation
  • Agitated tank (VAT) leaching
  • Counter current decantation (CCD)
  • Concentrate leach
  • Merrill–Crowe
  • Cyanide (reagent)

Flow Sheet: Source
Source: Source

Summary:

Palmarejo‘s processing flowsheet consists of a standard crushing and grinding circuit (Jaw crusher - SAG mill – ball mill), followed by flotation, where the flotation concentrate is subjected to an intensive cyanide leach and flotation tailing is treated in agitated cyanidation. Finally, a Merrill Crowe circuit is used to recover gold and silver from the leachates.

The plant is designed to achieve an overall recovery of approximately 94.0% of the gold and 91.0% of the silver as a doré.

The ball mill cyclone overflows at a nominal 80% minus 75 µm in size with a pulp density of 30% solids flows by gravity to the rougher conditioner tank, where the slurry is conditioned with Aero 404 and potassium amyl xanthate (PAX). The conditioner tank overflows to feed a bank of six 100m3 capacity tank cells. Rougher flotation occurs at the first bank of two tank cells, and scavenger flotation occurs sequentially down the bank. Frother and PAX are added to rougher feed and during the scavenging flotation.

Cleaner flotation tailings are recycled to the rougher flotation conditioner tank or alternatively to the 3rd or 5 th rougher cell for additional treatment.

Flotation tailings are transferred to the tailings thickener for dewatering, and tailings thickener overflow reports to the grinding circuit as recycled water. Thickener underflow, at approximately 60% solids, is transferred to the Float Tails agitated leach circuit for cyanide leaching and dissolution of residual gold and silver values.

The concentrate leaching circuit is located in the Leaching/Recovery Area of the mill facilities and is comprised of four agitated leach tanks, each with a nominal capacity of 200m3, providing a total leaching time of 48 hours.

Thickened flotation concentrate is pumped to the concentrate leach circuit. The slurry is then diluted to approximately 50% solids, and sodium cyanide solution is added to maintain a concentration of 10 g/L NaCN. Oxygen is injected to the concentrate leach tanks to enhance the silver dissolution process, and also enables cyanide solution strength reduction from 50 g/L to 10 g/L NaCN, resulting in a substantial reduction of cyanide consumption.

Leached slurry from the concentrate leach circuit is then pumped to a triple stage countercurrent decantation (CCD) circuit to recover the dissolved gold and silver values. Each stage consists of a high rate, 9.0m diameter thickener and an inter-stage mixing tank to enhance washing efficiency. Pregnant solution containing metal bearing overflows from the first CCD thickener is pumped to the pregnant solution tank for subsequent delivery to the Merrill Crowe circuit, located at the refinery building for further treatment. Thickened underflow from the final CCD thickener is pumped to an agitated leach circuit for additional leaching and potential recovery of residual metal values.

The flotation tailings leaching circuit is also located in the Leaching/Recovery Area of the mill facilities.

Pregnant solution from the flotation concentrate leach CCD first thickener overflow is pumped to one of three batch solution tanks, and then pumped to a Merrill Crowe system, at a flow rate ranging from 55 to 60m 3/hr.

The precipitate produced by Merrill Crowe is dried in two electrical dryer ovens before being smelted in a 600kg/hr capacity electric induction furnace and poured into 30kg dore ingots.

Dore ingots are shipped by armored truck to a refinery.

Recoveries & Grades:

CommodityParameter2021202020192018201720162015
Silver Recovery Rate, % 82.480.479.383.88688.484.3
Silver Head Grade, g/t 134.76152.59166.3222.54192.7160.47129.61
Gold Recovery Rate, % 92.889.984.388.99086.580.6
Gold Head Grade, g/t 2.062.42.743.433.092.741.71

Production:

CommodityUnits2022202120202019201820172016
Silver koz 6,000-7,000 ^6,8216,2696,7627,5167,2424,442
Gold oz 100,000-110,000 ^109,202110,608111,932122,722121,56973,913
All production numbers are expressed as metal in doré. ^ Guidance / Forecast.

Operational Metrics:

Metrics202120202019201820172016
Ore tonnes mined 2,100,990 tons1,760,871 tons1,083,906 tons
Tonnes milled 2,106,741 tons1,751,525 tons1,755,957 tons1,382,471 tons1,498,421 tons1,078,888 tons

Reserves at December 31, 2021:
Mineral Reserve reported above a variable gold equivalent cut-off grade that ranges from 1.94–2.51 g/t AuEq and an incremental development cut-off grade of 1.08 g/t AuEq.
Mineral Resource reported above a variable gold equivalent cut-off grade that ranges from 1.59-2.21 g/t AuEq.

CategoryTonnage CommodityGradeContained Metal
Proven 3,754 k tons Silver 4.39 oz/ton 16,480 koz
Proven 3,754 k tons Gold 0.066 oz/ton 247 koz
Probable 12,139 k tons Silver 3.78 oz/ton 45,875 koz
Probable 12,139 k tons Gold 0.052 oz/ton 637 koz
Proven & Probable 15,893 k tons Silver 3.92 oz/ton 62,355 koz
Proven & Probable 15,893 k tons Gold 0.056 oz/ton 884 koz
Measured 3,696 k tons Silver 3.89 oz/ton 14,373 koz
Measured 3,696 k tons Gold 0.053 oz/ton 195 koz
Indicated 17,377 k tons Silver 3.41 oz/ton 59,340 koz
Indicated 17,377 k tons Gold 0.049 oz/ton 852 koz
Measured & Indicated 21,073 k tons Silver 3.5 oz/ton 73,713 koz
Measured & Indicated 21,073 k tons Gold 0.05 oz/ton 1,047 koz
Inferred 4,713 k tons Silver 3.7 oz/ton 17,453 koz
Inferred 4,713 k tons Gold 0.052 oz/ton 246 koz

Commodity Production Costs:

CommodityUnits2022202120202019201820172016
Total cash costs (sold) Silver USD 14 / oz ^   12 / oz   9.14 / oz   9.13 / oz   7.64 / oz   9.96 / oz  
Total cash costs (sold) Gold USD 800 / oz ^   664 / oz   610 / oz   685 / oz   561 / oz   588 / oz  
Total cash costs (sold) Silver Equivalent USD 8.48 / oz   9.44 / oz   10.7 / oz  
^ Guidance / Forecast.

Operating Costs:

Units20212020
UG mining costs ($/ton mined) USD 4135.3
Processing costs ($/ton milled) USD 24.823.5
G&A ($/ton milled) USD 58.5

Financials:

Units2022202120202019201820172016
Capital expenditures (planned) M USD 52.5  
Capital expenditures M USD 36.5  25.5  32.7   29.4   29.9   35.8  
Sustaining costs M USD 22.5   22.7  
Revenue M USD 320.3  286.6  252.7   245.8   274.8   141.3  
After-tax Income M USD 59  67.4  21.6   25.2   16   43.5  
Operating Cash Flow M USD 50.5   139.9   26.7  



Heavy Mobile Equipment as of November 2, 2015:
Source: Source p.242
HME TypeModelQuantity
ANFO Loader Getman A64 1
Cable bolter Atlas Copco Cabletec LC 2
Drill (long hole) Atlas Copco SIMBA H 1254 1
Drill (long hole) Boart Longyear Stope Mate 1
Drill (long hole) Atlas Copco Simba M4CITH 3
Grader Caterpillar 120K 1
Jumbo Epiroc Boomer 282 4
Jumbo Atlas Copco Boomer S1D 1
Jumbo Atlas Copco Boomer C281 1
Load-Haul-Dump (LHD) Caterpillar R1700G 6
Load-Haul-Dump (LHD) Caterpillar R1600G 2
Load-Haul-Dump (LHD) Caterpillar R1300G 1
Load-Haul-Dump (LHD) TORO T1400 2
Load-Haul-Dump (LHD) Atlas Copco ST1030 2
Rock bolter Atlas Copco Boltec 235 6
Rock bolter RDH Boltmaster 200EH 1
Scissor Lift Marcotte M40 5
Truck (haul) Caterpillar AD45 7
Truck (haul) Caterpillar AD30 5

Mine Management:

Job TitleNameProfileRef. Date
Maintenance Manager José Gregorio Cardona Villafaña LinkedIn Nov 25, 2022
Process Manager Oscar León LinkedIn Nov 25, 2022

Staff:

EmployeesYear
923 2021
850 2020
876 2019
860 2018
878 2017
825 2016
765 2015

Corporate Filings & Presentations:

DocumentYear
Corporate Presentation 2022
Corporate Presentation 2021
Form 10-K 2021
Corporate Presentation 2020
Form 10-K 2020
Corporate Presentation 2019
Other 2019
Press Release 2019
Form 10-K 2018
Press Release 2018
Year-end Mineral Reserves 2018
Annual Report 2017
Year-end Mineral Reserves 2017
Annual Report 2016
Press Release 2016
Year-end Mineral Reserves 2016
Annual Report 2015
Technical Report 2015

Aerial view:

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