Peru

Coimolache Mine

Click for more information

Categories

Overview

Mine TypeOpen Pit
StatusActive
Commodities
  • Gold
  • Silver
  • Copper
Mining Method
  • Truck & Shovel / Loader
Production Start... Lock
Mine Life... Lock
SnapshotCoimolacé mine includes two processing lines: the Tantauatai leach field and the Ciénaga leach angle.

During 2023, the operation was focused on the Mirador, Tantahuatay 2 and Ciénaga Norte areas.

In 2023, priority was given to exploration works on the sulfide project, focusing the drilling plan on the high-grade zone. At the same time, the company continues to analyze the feasibility of the Tantauatai Sulfide Project.

On February 15, 2024, a Technical Report was released focusing on the Tantahuatay Sulfuros project, which is a continuation of the ongoing open pit oxide operation.

Buenaventura expects a year-on-year decline in gold due to limited leach pad capacity, as environmental permits required for leach pad expansion remain pending with continued delays from the Peruvian environmental authority (SENACE). Buenaventura expects to receive relevant permits in the 1H24, enabling construction of the necessary components during 2H24.

Owners

SourceSource
CompanyInterestOwnership
Estudios y Proyectos S.A.C. 15.67 % Indirect
Compania de Minas Buenaventura S.A.A. (operator) 40.09 % Indirect
Southern Copper Corp. 44.24 % Indirect
Coimolache is operated by Buenaventura, and wholly owned by Coimolache, in which we hold a 40.095% equity interest.

Compañía Minera Coimolache S.A. (CMC) was established, with 40.09% shareholding by Cía. Minera Buenaventura S.A.A. (BVN), 44.24% by Southern Copper Corporation (SPCC) and 15.67% by ESPRO S.A.C.

Contractors

Lock

- subscription is required.

Deposit type

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

Summary:

The Mine is located in the Hualgayoc Mining District, within the Chicama-Yanacocha corridor, in the Cajamarca-Cutervo region of the Cordillera Occidental, in northern Peru (Domain VI, INGEMMET). It is located within metallogenic belt XXI, which is a host to a number of Miocene epithermal Au-Ag deposits (INGEMMET, 2021).

The main mineralization systems in the Tantahuatay-Hualgayoc region are associated with Miocene bimodal magmatism-volcanism. The youngest rocks at the top of the stratigraphic column include Upper Miocene to Pleistocene tuffs and ignimbrites, and recent colluvial and eluvial deposits.

The Coimolache deposits are high sulphidation epithermal deposits. The oxide gold-silver mineralization is hosted in breccias associated with mainly silica alteration. Below the oxide level, there is predominantly arsenic-bearing copper mineralization, with a few occurrences of covellite and supergene chalcocite.

At Tantahuatay, a conceptual geological model derived from analysis of overlying alteration and mineralization suggests two targets for blind porphyry-style copper-gold mineralization at depth (Corbett, 2014).

The current Tantahuatay open pit mines gold from a high-sulphidation epithermal deposit hosted in silicified breccias with extensive silica alteration, which laterally grade into pervasive silicification and local alteration of marginal silica alunite. Enargite mineralization is locally discernible within the vugs in the pit and undoubtedly contributed to the high FeO content, becoming more evident below the oxidation base. Wall rocks in the open pit and drill holes consist of volcanic andesite, a subvolcanic andesite dome, and a pre- alteration porphyry with stockwork veins, all showing predominant silica-pyrophyllite alteration grading into silica-alunite in the uppermost portions. Fracture-controlled enargite-pyrite mineralization cuts the pyrophyllite alteration in the volcanic rocks and porphyry, as well as quartz stockwork veins, so the porphyry must predate the pervasive pyrophyllite alteration and also the epithermal event. The presence of dickite instead of the alunite typically deposited with enargite is indicative of a lower temperature high-sulphidation epithermal event (Corbett, 2014).

The Tantahuatay andesitic volcanic complex hosts a series of high-sulphidation epithermal deposits. It consists of five areas of gold-silver mineralization, all occurring in the supergene oxidation zones (Mirador Norte, Mirador Sur, Ciénaga Norte, Ciénaga Sur, and Tantahuatay).

Below the oxidation zone in the Tantahuatay area, significant copper-gold-silver mineralization occurs as pyrite and enargite veinlets, or disseminations and fracture fillings, and is associated with breccias and advanced argillic alteration.

A number of porphyry type copper-gold occurrences are also known in the general area. Gold mineralization is encountered in pyrite and enargite and is associated with intense quartzpyrophyllite alunite alteration and vuggy to massive quartz, concentrated in secondary permeability zones (Gustafson et al., 2004).

High Sulphidation Epithermal Mineralization
At Tantahuatay 2, 3, and 4, the primary copper-gold mineralization is associated with high sulphidation enargite-pyrite mineralization. The mineralization generally occurs as: a) brecciated cement and b) fine grained quartz, enargite-pyrite veinlets, and is typically associated with pervasive silicification of the wall rock, characterized by fine grained quartz. Sulphides and sulphosalts also occur in small amounts as disseminations along the margin of pyrophyllitediaspore-alunite patches (gusano texture).

Molybdenite
Three molybdenite styles observed in the Mine area have developed in at least two stages. The first style includes molybdenite that occurs in porphyry as disseminations in Type B veinlets with central lines of pyrite. The second style of molybdenite mineralization is present as molybdenite+pyrite veinlets cutting quartz altered rocks. The third style is molybdenite that occurs as disseminations in pyrophyllite-diaspore-alunite patches with pyrite. The second and third styles are younger than the first style and advanced argillic alteration.

Supergene Oxidation
Although glacial erosion has removed most of the oxide cover, there is sufficient residual oxide mineralization for resources to be estimated in two sectors, Ciénaga and the Tantahuatay 2 pit area Alunite from a hydrothermally altered dome is dated at 12.4 ± 0.4 Ma (K/Ar), inferred as the age of hydrothermal mineralization; also biotite from a post-mineral dike is dated at 8.6 ± 0.3 Ma (K/Ar) (Noble and McKee, 1999), indicating the Tantahuatay dome and associated mineralization to be slightly younger than the mineralization at Hualgayoc.

Other
In addition to the high sulphidation and porphyry type mineralization, there are other types in the district. There are Pb-Zn-Ag veins in Cretaceous carbonates east of the Rio Colorado fault. Further east, the Nicola Mine has several Pb-Zn-Ag veins. On the west side of the Rio Colorado fault, a reverse circulation drill hole north of Tantahuatay 5 intercepted 54 m of mineralization averaging 1.73% Zn and 0.45% Pb. Some intercepts in drill hole T28 were reported as a skarn type, from 554 m to 556 m (0.7 g/t Au, 37 g/t Cu; CMC drill core assay).

Tantahuatay Sulfuros project
Tantahuatay region shows various styles of mineralization including: high-sulfidation epithermal, porphyry, and skarn (Bissig, Clark, Rainbow, & Montgomery, 2015). Tantahuatay Sulfuros project includes those three deposits types.

High sulfidation epithermal deposit
Tantahuatay is a high sulfidation epithermal deposit that contains gold and silver mineralization in oxides, which is associated with hydrothermal and phreatomagmatic breccias, along with strong hydrothermal silicification (current operation). Below the oxide level, mineralization is dominated by sulfides, including minerals such as silica, pyrite, enargite, chalcosine and covelline (Tantahuatay Sulfuros project).

Two large mineralization type domains have been differentiated:

Arsenical copper: The first corresponds to the mineralization in the high sulfidation epithermal system with enargite domain and vertical zoning to chalcosine-coveline and chalcopyrite in contact with exoskarn.

Non-arsenical copper: related to the chalcopyrite-sphalerite mineralization that is hosted in the copper porphyries and exoskarn.

Both domains demonstrate a transition to the mineralization of the intermediate sulfidation type with gray copper mineralization, cadmium-rich sphalerite, bismuthinite, galena, stibnite, orpiment.

Mineralization of intermediate to low sulfidation type has been differentiated, related to the emplacement of a diatreme.

Reserves

Lock

- subscription is required.

Mining Methods

Lock

- subscription is required.

Comminution

Crushers and Mills

Milling equipment has not been reported.

Processing

Lock

- subscription is required.

Production

CommodityUnits2024202320222021202020192018201720162015
Gold koz  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe162173151151145
Silver koz  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe754791801711880
All production numbers are expressed as metal in doré. ^ Guidance / Forecast.

Operational metrics

Metrics2024202320222021202020192018201720162015
Daily mining rate  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe
Daily processing rate  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe
Stripping / waste ratio  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe
Ore tonnes mined  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe
Waste  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe
Total tonnes mined  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe
Tonnes processed  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe13,878,907 t13,384,291 t13,117,287 t10,624,498 t12,185,425 t
Daily processing capacity  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe
^ Guidance / Forecast.

Production Costs

CommodityUnits2023202220212020201920182017
Cash costs (sold) Silver USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 8.14 / oz   8.39 / oz   6.98 / oz  
Credits (by-product) Gold USD  ....  Subscribe  ....  Subscribe  ....  Subscribe -77 / oz  
Cash costs (sold) Gold USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 684 / oz   675 / oz   517 / oz  
All-in sustaining costs (AISC) Gold USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 900 / oz **  
** Net of By-Product.

Financials

Units2023202220212020201920182017
Capital expenditures M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 28.9  
Revenue M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 241.2   225.4   203.8  
Operating Income M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 42.5   47.5  
Gross profit M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 54   54.6  
Pre-tax Income M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 39.8   44  
After-tax Income M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 28.5   25.6   50.8  
Book Value M USD  ....  Subscribe  ....  Subscribe

Heavy Mobile Equipment

Lock

- subscription is required.

Personnel

Mine Management

Job TitleNameProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required Jun 4, 2024
....................... Subscription required ....................... Subscription required Subscription required Jun 4, 2024
....................... Subscription required ....................... Subscription required Subscription required Jun 4, 2024
....................... Subscription required ....................... Subscription required Subscription required Jun 4, 2024
....................... Subscription required ....................... Subscription required Subscription required Jun 4, 2024
....................... Subscription required ....................... Subscription required Subscription required Jun 4, 2024

EmployeesContractorsTotal WorkforceYear
...... Subscription required ...... Subscription required ...... Subscription required 2023
...... Subscription required ...... Subscription required ...... Subscription required 2022
...... Subscription required ...... Subscription required ...... Subscription required 2021
...... Subscription required ...... Subscription required ...... Subscription required 2020
...... Subscription required ...... Subscription required ...... Subscription required 2019
...... Subscription required ...... Subscription required ...... Subscription required 2018
...... Subscription required 2017
...... Subscription required 2016

Aerial view:

Lock

- subscription is required.