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Mexico
Bolivar Mine (Bolivar (Expansion) Project)

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 Location:
54 km NE from Choix, Chihuahua, Mexico

  Regional Office:
Fernando de Borja No. 100 Col. San Felipe
Chihuahua
Chihuahua, Mexico
C.P. 31203
Phone  ...  Subscription required
Fax+52-614-414-3884
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
  • Copper
  • Silver
  • Gold
  • Zinc
Mining Method
  • Sub-level stoping
  • Longhole stoping
  • Room-and-pillar
Processing
  • Flotation
Mine Life7 years (as of Jan 1, 2020)
October 20, 2020 - Sierra Metals Inc. is pleased to report the results of a Preliminary Economic Assessment (“PEA”) regarding the Company’s Bolivar Mine.

The PEA study compared the value of the current operations at Bolivar at 5,000 TPD against several output expansion alternatives from 7,000 to 15,000 TPD and determined 10,000 TPD as the optimum production level based on a current mineral resource base.
Latest NewsSierra Metals Announces Positive Preliminary Economic Assessment Results for Doubling Output at Its Bolivar Mine in Mexico to 10,000 Tonnes Per Day     October 20, 2020


Owners

Source: p. 14
CompanyInterestOwnership
Sierra Metals Inc. 100 % Indirect
Dia Bras Mexicana SA de CV 100 % Direct
The Bolivar property is owned by Sierra Metals, formerly known as Dia Bras Exploration, Inc., through subsidiary companies Dia Bras Mexicana S.A. de C.V. and EXMIN S.A. de C.V. (collectively Dia Bras).

Deposit Type

  • Skarn


Summary:

The Bolivar deposit is classified as a high-grade Cu-Zn skarn and exhibits many characteristics common to this deposit type (Meinert, 2007). The term skarn refers to coarse-grained calcium or magnesian silicate alteration formed at relatively high temperatures by the replacement of the original rock, which is often carbonate-rich.

Skarn alteration and mineralization at the Bolivar property is hosted primarily in a package of sedimentary rocks that occur as a layer or lens within the LVS (Reynolds, 2008). All sedimentary units have undergone low grade metamorphism. The lowermost sedimentary horizon observed is a dolostone which ranges from 24 m to 40 m in thickness. The lower part of the dolostone horizon is interlayered with siltstone. To the south, progressively less of the sedimentary sequence is cut out by granodioritic intrusive rocks and the dolostone is observed to be underlain by a siltstone horizon. The lower siltstone unconformably overlies the LVS. The dolostone is overlain by a discrete layer of siltstone. The average thickness of this siltstone unit is 12 to 30 m. Horizons of argillaceous dolostone (50 m thick) and argillaceous limestone (9 m thick) are above the siltstone marker layer. The uppermost sedimentary horizon is a limestone with local chert and argillaceous laminations. The vertical thickness of this horizon varies considerably in cross-section (108 to 173 m) and this variation is attributed to paleo-topographic relief. The upper contact of the limestone is an unconformity with the LVS.

The most important igneous rocks on the property are the Piedras Verde granodiorite and related dikes and sills. All are slightly porphyritic but none are a true porphyry. The Piedras Verde granodiorite exhibits a range of textural variations and compositions. The average composition is very similar to plutons related to Cu skarns (Meinert, 2007). There is no indication of an Au association.

The dikes locally cut the granodiorite, have planar, chilled contacts, and are generally finely crystalline. Both their texture and crosscutting relations suggest that the dikes are younger and shallower than the granodiorite. Both granodiorite and andesite dikes have alteration and locally skarn, along their contacts. In addition, endoskarn affects both the granodiorite and in rare cases, the andesite dikes. Thus, these rocks are older than or at best coeval with alteration/mineralization. The presence of skarn veins cutting an andesite dike is clear evidence that at least some skarn is later than at least some of the andesite dikes. A closer association of granodiorite with skarn alteration and mineralization is suggested by local K-silicate veining of the granodiorite and the zonation of skarn relative to this contact.

Mineralization at the Bolivar property is hosted by skarn alteration in carbonate rocks adjacent to the Piedras Verde granodiorite (Meinert, 2007). Orientations of the skarn vary dramatically, although the majority are gently-dipping. Thicknesses vary from 2 m to over 20 m. Skarn mineralization is strongly zoned, with proximal Cu-rich garnet skarn in the South Bolivar area, close to igneous contacts, and more distal Zn-rich garnet+pyroxene skarn in the northern Bolivar and southern skarn zones near El Val. The presence of chalcopyrite+bornite dominant skarn (lacking sphalerite) in the South Bolivar area, along with K-silicate veins in the adjacent granodiorite suggests that this zone is close to a center of hydrothermal fluid activity. In contrast, the main Bolivar Mine is characterized by Zn>Cu and more distal skarn mineralogy such as pyroxene>garnet and pale green and brown garnets.

Alteration is zoned relative to fluid flow channels. From proximal to distal, the observed sequence is: red-brown garnet to brown garnet with chalcopyrite ± bornite ± magnetite to green garnet ± pyroxene with chalcopyrite + sphalerite to massive sulfide (sphalerite ± chalcopyrite ± galena) to marble with stylolites and other fluid escape structures.

Mineralization exhibits strong stratigraphic control and two stratigraphic horizons host the majority: an upper calcic horizon, which predominantly hosts Zn-rich mineralization, and a lower dolomitic horizon, which predominantly hosts Cu-rich mineralization. In both cases, the highest grade are developed where fault or vein structures and associated breccia zones cross these favorable horizons near skarn-marble contacts. Meinert (2007) suggested that hydrothermal fluids moved up along the Piedras Verdes Granodiorite contact, forming skarn and periodically undergoing phase separation that caused brecciation. Zones of breccia follow faults like the Rosario, Fernandez, and Breccia Linda trends as well as nearly vertical breccia pipes such as La Increible.


Mining Methods

  • Sub-level stoping
  • Longhole stoping
  • Room-and-pillar


Summary:

The Bolivar Mine is currently mined by the sub-level stoping and room and pillar methods and the specific method applied to a particular area of the mine is determined by geotechnical constraints, mineralization trends, dimensions and mine production targets.

Current production at Bolivar comes from the El Gallo Inferior, Chimenea 1 and 2 and the Bolivar West mineralized zones. Mineralized material is currently hauled to the surface using one of several adits or declines accessing the mineralized zones and is then dumped onto small pads outside the portals. The mineralized material is then loaded into rigid-frame, over-the-road trucks and hauled on a gravel road approximately 5.1 km south to the Piedras Verdes Mill. As explained in more detail in Section 18, the mine is constructing an underground tunnel that will enable mineralized material to be delivered via underground truck transport to a portal adjacent to the Mill.

Sub-Level Stoping - Bolivar West
The longhole method is applied in the shallow dipping mineralized bodies in Bolivar West. Excavation for longholes with openings of 9.0 m and pillars of 7.0 m x 7.0 m for stope heights between 12.0 m and 15.0 m. From the access ramp, access to the mineralized material is established in the central part of the chamber and the mineral cut begins. A drive is developed within the mineralized material, then the drilling of long holes is carried out and extraction begins. Ramps are established in some cases in mineralized material to minimize waste extraction.

Sub-Level Stoping - El Gallo Inferior
The longhole method is applied to the mineralized structures at the El Gallo Inferior deposit. Each level has 20.0 m of vertical stope height and is accessed through a ramp to the central part of the level. A mineralized material drive is developed to the floor of the structure and then the cutting of the mineralized mineral begins through the mineralized material drive and continues with the drilling of longholes. Then, the mineralized material is extracted through the second ore drive made in the lower part of the level. After every 45.0 m of advance in the mineralized material drive, a perpendicular support pillar of 10.0 m is left.

The primary access is made via ramps of 5.0 m x 5.0 m and then the accesses to the stopes and ore drives are developed with a section of 4.0 m x 4.0 m. The ramps are designed with a maximum gradient of 12%.

Drilling, Blasting, Loading and Hauling
The electrohydraulic jumbos conduct the lateral development of the main tasks such as ramps, crossings or bypasses. The ramps have a section of 5.0 m x 5.0 m (width / height) and the accesses to the stopes and mineralized material drive have a section of 4.0 m x 4.0 m (width / height).

Raptor radial drilling jumbos are used for the production of the stopes. The drilling and blasting designs are developed by the technicians at the mine.

After blasting, the face is mucked by scoops, and mineralized material is loaded into trucks and hauled to the ramp portal on surface.

The base case LOM production and development schedule generated for the Bolivar mineable
inventory based on 5,000 tpd (1.8 M t/y).


Crushing and Grinding
Crusher / Mill TypeModelSizePowerQuantity
Jaw crusher 1
Cone crusher ....................... Subscription required 1
Cone crusher ....................... Subscription required 1

Summary:

Crushing Stage
The crushing stage is supplied with mineralized material hauled from the mine site using contractor operated haul trucks. A typical haul truck has approximately 20 tonnes capacity and delivers mineralized material from the mine area to the primary crusher’s mineralized material stockpiling area. Trucks can dump directly to the primary crusher or alternatively, to one of several stockpiles. Typically, a front-end loader reclaims mineralized material from the stockpiles and then feeds the jaw crusher.

The crushing plant is fed through a hopper equipped with a 20-inch x 20-inch static grizzly that discharges to a jaw crusher operating in open circuit. The nominal four-inch material discharging from the jaw crusher is classified by two double-deck vibrating screens. The top screen is two inches by one inch and the bottom screen is 3/4 inch by 3/8 inch. Material smaller than 3/8 inch becomes the final crushed product that is transferred to two silos having an individual capacity of 1,000 tonnes each. The vibrating screen’s oversize feeds a secondary crushing stage consisting of two cone crushers. The top screen is conveyed to a Sandvik HC660 cone crusher and the bottom screen oversize is conveyed to a Metso HP-300 cone crusher. The cone crusher’s discharge joins the primary crusher’s discharge and feeds the double-deck vibrating screens.

Grinding Circuit
Feed to the grinding circuit is sourced from two 1,000 tonne silos that hold the final crushed product from the crushing plant. The grinding circuit consists of conventional ball mills operating in closedcircuit operation with hydrocyclones. Two 9.5 ft x 14 ft ball mills operate in parallel, each one in closed circuit with a hydrocyclone cluster. The two ball mills underwent complete overhauls during the end of 2017 to improve mechanical availability. The hydrocyclones were changed from D26 to D20 to improve plant stability. The product size in the cyclone overflow ranges between 34% and 48% passing 75 micrometers, with an average size of 43.5% passing 75 micrometers. The hydrocyclone overflow feeds the flotation circuit. The hydrocyclone underflow stream is returned to the ball mills for further size reduction.


Processing

  • Flotation

Flow Sheet: Subscription required

Summary:

The Piedras Verdes Plant, located 5.1 kilometers from the Bolivar Mine, uses a conventional crushing-grinding-flotation circuit to recover mineralized mineral and to produce commercial quality copper concentrates with silver and gold by-product credits.

Bolivar’s Piedras Verdes processing facilities started operating in October 2011 at 1,000 tpd of nominal throughput. The ore processing capacity was expanded to 2,000 tpd in mid-2013. The mill has been upgraded since and the current nominal throughput capacity is 3,500 tpd although the mine has exceeded this throughput on many occasions and in 2020 has achieved 5,000 tpd.

Piedras Verdes operates a conventional concentration plant consisting of crushing, grinding, flotation, thickening of concentrates, filtration of concentrates, and tailings disposal.

The operation is completely manual with no automation or online monitoring being used in the processing circuit. The grinding product, or flotation feed pa ........

Recoveries & Grades:

CommodityParameter2019201820172016201520142013
Copper Recovery Rate, %  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required
Copper Head Grade, % 0.850.950.9611.151.221.3
Silver Recovery Rate, %  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required
Silver Head Grade, g/t 19.817.714.916.720.622.525.9
Gold Recovery Rate, %  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required
Gold Head Grade, g/t 0.270.170.170.190.30.23
Subscription required - Subscription is required.

Production:

CommodityProductUnits201920182017201620152014
Copper Metal in concentrate k lbs  ......  Subscription required  ......  Subscription required15,05617,10917,62914,946
Silver Metal in concentrate koz  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required
Gold Metal in concentrate oz  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required
Silver Equivalent Payable metal koz  ......  Subscription required  ......  Subscription required  ......  Subscription required
Copper Equivalent Payable metal k lbs  ......  Subscription required  ......  Subscription required  ......  Subscription required
Copper Equivalent Metal in concentrate k lbs  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required
Zinc Equivalent Payable metal k lbs  ......  Subscription required  ......  Subscription required  ......  Subscription required
Silver Equivalent Metal in concentrate koz  ......  Subscription required  ......  Subscription required  ......  Subscription required
Subscription required - Subscription is required.

Operational Metrics:

Metrics201920182017201620152014
Tonnes processed  ......  Subscription required  ......  Subscription required  ......  Subscription required950,398 t830,447 t665,951 t
Daily processing capacity  ......  Subscription required  ......  Subscription required  ......  Subscription required3,000 t3,000 t
Daily processing rate  ......  Subscription required  ......  Subscription required  ......  Subscription required2,715 t2,373 t1,903 t
Subscription required - Subscription is required.

Reserves at December 31, 2019:

CategoryTonnage CommodityGradeContained Metal
Probable 7.5 Mt Copper 0.69 % 114.5 M lbs
Probable 7.5 Mt Silver 13.4 g/t 3.2 M oz
Probable 7.5 Mt Gold 0.22 g/t 53.5 koz
Probable 7.5 Mt Copper Equivalent 0.87 % 143 M lbs
Indicated 19.5 Mt Copper 0.78 % 332.3 M lbs
Indicated 19.5 Mt Silver 15.4 g/t 9.5 M oz
Indicated 19.5 Mt Gold 0.2 g/t 128.5 koz
Indicated 19.5 Mt Copper Equivalent 0.96 % 411.1 M lbs
Inferred 21.5 Mt Copper 0.78 % 371.3 M lbs
Inferred 21.5 Mt Silver 14.2 g/t 9.8 M oz
Inferred 21.5 Mt Gold 0.21 g/t 145.8 koz
Inferred 21.5 Mt Copper Equivalent 0.96 % 456.2 M lbs

Commodity Production Costs:

CommodityUnits201920182017201620152014
Cash costs (sold) Zinc Equivalent USD  ......  Subscription required  ......  Subscription required
Cash costs (sold) Copper Equivalent USD  ......  Subscription required  ......  Subscription required 1.49 / lb 1.15 / lb 1.34 / lb 1.28 / lb
Cash costs (sold) Silver Equivalent USD  ......  Subscription required  ......  Subscription required 9.06 / oz 7.64 / oz 8.82 / oz
All-in sustaining costs (sold) Zinc Equivalent USD  ......  Subscription required  ......  Subscription required
All-in sustaining costs (sold) Copper Equivalent USD  ......  Subscription required  ......  Subscription required 2.68 / lb 2.28 / lb 2.33 / lb 2.43 / lb
All-in sustaining costs (sold) Silver Equivalent USD  ......  Subscription required  ......  Subscription required 16.3 / oz 15.2 / oz 15.2 / oz
Subscription required - Subscription is required.

Operating Costs:

Units201920182017201620152014
Total operating costs ($/t milled) USD 29.427.724.924.427.933.2

Financials:

Units2020201920182017201620152014
Capital expenditures (planned) M USD  ......  Subscription required
Capital expenditures M USD  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required 7.85   7.4  
Sustaining costs M USD  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required 5.71   3.33  
Revenue M USD  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required 41.8   41.7  
Gross profit M USD  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required 4.31  
After-tax Income M USD  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required -3.29  
EBITDA M USD  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required 4.23  
Subscription required - Subscription is required


Heavy Mobile Equipment as of June 28, 2018:
HME TypeModelSizeQuantityStatus
Drill jumbo (single boom) ....................... Subscription required 1 Existing
Drill jumbo (single boom) ....................... Subscription required 1 Existing
Drill jumbo (two boom) ....................... Subscription required 1 Existing
Drill jumbo (two boom) ....................... Subscription required 2 Existing
Grader ....................... Subscription required 1 Existing
Scoop Tram ....................... Subscription required 3.5 cu. yd 1 Existing
Scoop Tram ....................... Subscription required 8 cu. yd 3 Existing
Scoop Tram ....................... Subscription required 6 cu. yd 1 Existing
Scoop Tram ....................... Subscription required 6 cu. yd 1 Existing
....................... Subscription required ....................... Subscription required ....................... Subscription required 5 Proposed
Underground truck ....................... Subscription required 30 t 3 Existing
....................... Subscription required ....................... Subscription required 12 Proposed
Underground truck ....................... Subscription required 16 t 1 Existing
Underground truck ....................... Subscription required 30 t 1 Existing
Subscription required - Subscription is required.

Mine Management:

Job TitleNameProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required Apr 8, 2020
Subscription required - Subscription is required.

Staff:

EmployeesContractorsTotal WorkforceYear
Subscription required Subscription required Subscription required 2019

Corporate Filings & Presentations:

DocumentYear
................................... Subscription required 2020
................................... Subscription required 2020
................................... Subscription required 2020
................................... Subscription required 2019
................................... Subscription required 2019
................................... Subscription required 2019
................................... Subscription required 2018
................................... Subscription required 2018
................................... Subscription required 2018
................................... Subscription required 2018
................................... Subscription required 2018
Corporate Presentation 2017
Management Discussion & Analysis 2017
Technical Report 2017
Annual Information Form 2016
Corporate Presentation 2016
Corporate Presentation 2016
Management Discussion & Analysis 2016
Press Release 2016
Management Discussion & Analysis 2015
Management Discussion & Analysis 2014
Technical Report 2013
Subscription required - Subscription is required.

News:

NewsDate
Sierra Metals Announces Positive Preliminary Economic Assessment Results for Doubling Output at Its Bolivar Mine in Mexico to 10,000 Tonnes Per Day October 20, 2020
Sierra Metals Announces Filing of NI 43-101 Technical Report on Reserves and Resources for the Bolivar Mine in Mexico May 14, 2020
Sierra Metals Increases Mineral Resources Versus Its December 2019 Announcement and Updates the Mineral Reserve Estimate for Its Bolivar Mine, Mexico March 31, 2020
Sierra Metals Updates the Mineral Resource Estimate for Its Bolivar Mine, Mexico December 31, 2019
Sierra Metals Reports Construction at Bolivar Mine/Mill in Mexico Has Been Completed Ahead of Schedule January 9, 2019
Sierra Metals Announces Filing of the PEA Report for its Bolivar Mine in Mexico August 23, 2018
Sierra Metals Announces Positive PEA Results for a 67% Output Expansion at its Bolivar Mine in Mexico July 9, 2018
Sierra Metals Announces Filing of NI 43-101 Technical Report on the Bolivar Mine in Mexico July 6, 2018

Aerial view:

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