Spain

Cobre Las Cruces Mine

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Overview

Mine TypeTailings
Commodities
  • Copper
  • Gold
Mining Method
  • Truck & Shovel / Loader
Production Start... Lock
Mine Life2023
ShapshotIn 2021, the Las Cruces mine transitioned from open-pit mining to re-processing of high-grade tailings, which is expected to continue until the third quarter of 2023 while work on the Las Cruces Underground Project advances. The proposed underground project involves supplementing the existing copper facilities at Las Cruces with new processing capacity for zinc, silver and lead.

The water concession license was granted in March 2023 and all licenses and permits are now in place for approval of the project. The technical and study work on the polymetallic refinery project are expected to continue with all permits required to carry out the project now granted.

Owners

SourceSource
CompanyInterestOwnership
First Quantum Minerals Ltd. 100 % Indirect
Cobre Las Cruces, S.A. (operator) 100 % Direct
Cobre Las Cruces S.A. is the owner and operator of the Cobre Las Cruces mine in Spain. Cobre Las Cruces S.A. is an indirect wholly-owned subsidiary of the First Quantum Minerals Ltd.

Contractors

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Deposit type

  • VMS
  • Breccia pipe / Stockwork
  • Tailings

Summary:

The Las Cruces deposit is located within the Iberian Pyrite Belt and classed as a Volcanogenic Massive Sulphide (VHMS) deposit. VHMS mineralisation results from precipitation of metals associated with circulating hydrothermal fluids in volcanically active sub-marine areas. The metals precipitate as sulphides (pyrite/phyrrohtite with variable base metal sulphides such as chalcopyrite, sphalerite and galena) and are inter-layered to varying degrees with volcanic sediments.

The Las Cruces deposit, as per many other VHMS deposits, is characterised by a dipping massive sulphide horizon underlain by a stockwork vein system which are both hosted within shales and felsic volcanics. However, at Las Cruces, post deposition tectonism uplifted the deposit, exposing it to erosion and weathering with partial oxidation of some of the primary sulphides. This resulted in a copper leached gossan, which retained the relatively immobile gold and silver and overly the secondary sulphide horizons. The zones of primary sulphide mineralisation are the source of the current gossan and secondary sulphide zones and are key horizons for defining continuous volumes of similar geology and metal tenor. The zones of gossan, secondary sulphide, primary sulphide and stockwork are used as key domains for Mineral Resource estimation.

Mineralisation is characterised by a notable iron oxide gossan which occurs directly above a welldeveloped, flat lying secondary sulphide zone followed by an underlying north dipping (40 degrees) primary massive sulphide zone. The economically important secondary sulphide (HC) zone is about 150 m below surface.

The Gossan Zone is a 10 m to 20 m thick sub-horizontal iron stained oxide zone, leached of copper and sulphur, but contains relatively high levels of gold, silver and lead. While the contained Gossan metals are not recoverable from the current copper leaching and electro winning processing facilities at Las Cruces there is nevertheless a reasonable expectation that they are economic.

A thin (less than 5 m thick) Depleted Zone (DZ), containing variable but moderate copper mineralisation, represents a transition between the overlying Gossan Zone and the underlying secondary sulphide mineralisation. The DZ consists of a layer of sandy, pyritic material.

The underlying secondary sulphide mineralisation, known as the High Copper Main Zone (HC), has high copper grades due to supergene alteration of primary copper sulphides to secondary copper sulphides as well as from leaching copper from sulphides originally located in the overlying oxidised Gossan Zone. The HC zone has mostly chalcocite with minor bornite and covellite. Mineralisation strikes approximately 1,000 m east west and ranges from 40 m to 300 m wide in the north south direction with an average thickness of 40 m. Cobre Las Cruces Mineral Resources is comprised mostly of HC mineralisation.

A small secondary sulphide zone, known as the High Copper Small Zone (HC4), measures 200 m east west, 100 m north south and is on average 20 m thick. The HC4 mineralisation dips at 40 degrees west- north-west and is located directly below HC and PMS. HC4 orientation is due to remobilisation of copper along a structural fault zone having a similar orientation. While HC4 has similar copper grades to HC, it has been interpreted as a separate domain due to its distinct shape and orientation. Copper mineralisation is comprised mainly of covellite with chalcocite and digenite filling veins and gaps.

Primary sulfide mineralisation
Primary sulfide mineralisation at Las Cruces forms a single, large massive sulfide lens approximately 1,000m along strike, 500m down dip and 30 to 130m thick. The lens dips between 25° to 45° north. In the shallower open pit areas, dips can increase up to 50° due to imbricate faulting. Primary mineralisation underlies HCH (secondary) mineralisation and is open at depth and to the northeast. Mineralisation thickens to the west but is truncated by a north-south striking fault. The massive sulfide lens is underlain by a large stockwork mineralised zone that is accompanied by hydrothermal alteration.

The primary massive sulfides show distinct metal zoning with an upper Zn-rich zone and a lower Cu-rich zone which are often interbedded with centrally located barren massive pyrite. The sulfide mineral assemblage is typical of IPB deposits and is dominated by pyrite with chalcopyrite, sphalerite, galena and traces of tetrahedrite-tennantite, Bi-Pb sulphosalts, bismuthinite, stannite-kesterite, and cassiterite, together with quartz, barite, siderite, Ba-bearing sericite, and chlorite, and traces of rutile and zircon. Euhedral arsenopyrite is common near/within the hosting black shale. The presence of enargite and covellite are noted but these tend to be limited to the overlying secondary zones.

The massive sulfides show conspicuous layering with few clear sedimentary features. Features include banding and graded bedding, especially in the interbedded shale and chert. Within the copper-rich zones, paragenetically early pyrite forms aggregates of minute framboids (<20 µm) with interstitial pyrrhotite, and is partially recrystallized to small (<30 µm) euhedral crystals with few inclusions. It is cemented by a widespread, fine-grained, porous pyrite intergrown with chalcopyrite. Voids are commonly infilled with sphalerite and minor galena and tetrahedrite, and lined with botryoidal pyrite. Also, the sulfides present abundant colloform and circular-like structures, as well as a continuous layering that show fibrous growth.

The polymetallic zones contain centimetre-thick bands of alternating pyrite + chalcopyrite and sphalerite + chalcopyrite + galena. The sulfides other than pyrite show widespread recrystallization to a granoblastic assemblage hosting abundant rains of minute subhedral pyrite. The sphalerite is iron- poor (Zn48-50 Fe0.4-1.3 S49-51) and displays abundant evidence of late replacement by chalcopyrite, including the presence of chalcopyrite disease and replacements along veins and grain edges. These textures suggest widespread hydrothermal refining with replacement of the early sphalerite-galena by late chalcopyrite via hotter hydrothermal fluids. Locally, concentric zones, some millimetres to 1 cm in diameter, have an internal zone composed of sphalerite and an outer rim of chalcopyrite; these are interpreted as fluid conduits. The sphalerite and chalcopyrite contain inclusions of tetrahedrite-tennantite that show widespread As-Sb substitution. Also present are abundant wittichenite and more rare minerals of the aikinite-bismuthinite series occurring in small (<25 µm) grains intergrown with galena and bismuthinite, and hosted by chalcopyrite. Cassiterite forms minute sub-euhedral crystals, 3–10 µm in diameter, enclosed by the sphalerite and chalcopyrite.

Widespread late recrystallization has masked most of the primary features, leading to the formation of coarse (>500 µm) euhedral to sub-euhedral aggregates of sulfides. Deformation is responsible for the formation of alternating layers of sphalerite-chalcopyrite-galena and pyrite.

While the uppermost shale-hosted massive sulfides seem to be exhalative, the lowermost orebody seems to have been formed mainly by replacement.

The stockwork and related hydrothermal zone tends to be copper rich with localised zinc, extends some 200m beneath the massive sulfides and is hosted in hyaloclastic dacite and shale having chlorite ± quartz alteration. The stockwork veins are between 0.5 to 2cm thick and are folded or sub-parallel to the dominant foliation.

Tailings
The TSF is an engineered structure constructed from compacted marl and a synthetic liner. This facility receives dewatered leach residue from the operations for permanent storage. The tailings are passed through vertical press filters to produce a very-low moisture content final tails product. As of the end of 2022 the TSF contains 20 Mt.

Reserves

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Mining Methods

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Comminution

Crushers and Mills

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Processing

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Production

CommodityUnits2023202220212020201920182017
Copper t 0000000000000000000000070,73873,664
All production numbers are expressed as cathode. ^ Guidance / Forecast.

Operational metrics

Metrics202220212020201920182017
Annual production capacity 00000000000000000000
Tonnes processed 00000000000000001,544 kt1,619 kt
Ore tonnes mined 0000000001,682 kt2,422 kt
Waste OP 0000000014,936 kt14,589 kt
Total tonnes mined 0000
Annual processing capacity 00

Production Costs

CommodityUnits202220212020201920182017
All-in sustaining costs (AISC) Copper USD 000 000 000 1.35 / lb   1.16 / lb   1.06 / lb  
C1 cash costs Copper USD 000 000 000 1.17 / lb   0.9 / lb   0.86 / lb  
C3 fully allocated costs Copper USD 000 00 000 3.08 / lb   2.25 / lb   2.15 / lb  

Financials

Units2023202220212020201920182017
Capital expenditures (planned) M USD  ....  Subscribe
Capital expenditures M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe 34   22  
Revenue M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 470   461  
Gross profit M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 116   106  
Operating Income M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe 120   102  
EBITDA M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 326   316  

Heavy Mobile Equipment

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Personnel

Mine Management

Source Source
Job TitleNameProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required May 28, 2023
....................... Subscription required ....................... Subscription required Subscription required May 28, 2023
....................... Subscription required ....................... Subscription required Subscription required May 28, 2023
....................... Subscription required ....................... Subscription required Subscription required May 28, 2023
....................... Subscription required ....................... Subscription required Subscription required May 31, 2023
....................... Subscription required ....................... Subscription required Subscription required May 31, 2023

Total WorkforceYear
Subscription required 2017
Subscription required 2016
Subscription required 2015

Aerial view:

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