United States

Eagle Mine

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Overview

Mine TypeUnderground
StatusActive
Commodities
  • Nickel
  • Copper
  • Silver
  • Gold
Mining Method
  • Transverse open stoping
  • Sub-level open stoping (SLOS)
  • Longitudinal open stoping
  • Drift & Fill
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Mine Life... Lock
SnapshotThe Eagle mine has two active mineralized zones called Eagle and Eagle East.

The development of the third zone, the Keel Zone, commenced in Q1 2023, and the first ore production is expected to occur in late 2024 or early 2025.

Owners

SourceSource
CompanyInterestOwnership
Lundin Mining Corp. 100 % Indirect
Eagle Mine LLC (operator) 100 % Direct
Eagle Mine means the Eagle nickel and copper mine owned by Eagle Mine LLC, a wholly-owned indirect subsidiary of the Lundin Mining.

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Deposit type

  • Magmatic

Summary:

Deposit Type
Magmatic sulphide deposits containing nickel and copper, with or without PGMs, account for approximately 60% of the world’s nickel production and are active exploration targets in the United States and elsewhere. On the basis of their principal metal production, magmatic sulphide deposits in mafic rocks can be divided into sulphide rich and sulphide poor. Sulphide rich deposits typically have 10% to 90% sulphide minerals and have economic value primarily because of their nickel and copper contents. Sulphide poor deposits typically contain 0.5% to 5% sulphide minerals and are exploited principally for Platinum Group Metals (PGM).

The Eagle and Eagle East deposits are sulphide rich and high-grade magmatic sulphide accumulations containing nickel-copper mineralization and minor amounts of cobalt and PGMs. The economic minerals associated with these deposits are predominately pentlandite and chalcopyrite.

The mineralization process common to all primary magmatic sulphide deposits consists of: 1) Metal-rich ultramafic magma intruding into the crust, typically in an extensional environment; 2) Sulphur saturation through geochemical contamination by crustal rocks resulting in primary sulphide droplets forming; 3) Metal enrichment of sulphides by interaction with large volumes of subsequent magma flow; and 4) Deposition of sulphides by density settling where magma flow slows due to structural traps or major changes in the geometry of the plumbing system (going from a small conduit to a large chamber, etc.).

Several varieties of this deposit type occur within the primary magmatic sulphide model, ranging from komatiite lava flow deposits like Raglan, to meteor impact triggered partial melting like Sudbury, to conduit style mineralization like Eagle and Voisey’s Bay, and layered mafic complex mineralization like the Duluth complex.

At Eagle, the conceptual model is that of a series of magma conduits connect several larger magma chambers and exploring for high grade orebodies is reliant on tracing the conduits from one chamber to the next. The model has proven successful with the discovery of the Eagle East deposit which was discovered as the result of directional drilling to follow the conduit from the much larger and lower grade Eagle East peridotite. Drilling between 2016 and 2018 defined a large gabbroic intrusion that truncates the Eagle East peridotite at depth and is interpreted to be a younger intrusion which occupies the same structural plumbing as Eagle East, locally obliterating the peridotite intrusion.

The likely depositional process for the formation of the Eagle East deposit is that mineralized peridotite moving upward along a vertical intersection of mantle-tapping structures (now occupied by the gabbro intrusion) carried disseminated sulphide droplets in a high-volume magma flow, and the sulphides were dropped from the magma when they exited the small 90-degree bend in the magma conduit at the east end of Eagle East. This likely resulted in a significant pressure and velocity gradient, resulting in high velocity magma slowing down significantly in the horizontal portion of the conduit, dropping dense sulphides. Additionally, back-draining of sulphides from higher in the intrusion and ponding of sulphides in the horizontal section is likely to be a contributing factor to the formation of high-grade massive sulphide and semi-massive sulphide.

Mineralization
Eagle and Eagle East are part of the same ultramafic intrusive complex and both host high grade primary magmatic nickel copper sulphide mineralization. Mineralization styles are similar at Eagle and Eagle East, consisting of ovoid to pipe-like bodies of mineralized peridotite with concentrations of sulphide mineralization along the base of the intrusion resulting in the accumulation of semi-massive sulphide, and a central core zone of massive sulphide. Two types of potentially economic mineralization are found in Eagle and Eagle East: semimassive sulphides and massive sulphides. Disseminated mineralization is also encountered in the peridotite intrusive, however, because it is not economic, the mineralized peridotite with disseminated sulphides has been considered as an intrusive and not a mineralized unit.

Eagle
The intrusion hosting Eagle is elongated east-west with a maximum length of 480 m and maximum width of approximately 100 m near surface. The intrusion narrows to approximately 10 m wide at the limit of drilling, 290 m below surface (145 m RL). The sulphide bodies within the intrusion comprise an irregular mass broadly aligned with the strike and dip of an ovoid dilatant zone occupied by the peridotite. The bodies subtend a volume measuring 330 m in strike length by 270 m vertically, abruptly terminating on the west and tapering to the east with a maximum thickness in the middle of approximately 135 m. At the east and west ends of this volume are two bodies of semi-massive sulphides (SMSU), termed SMSUE and SMSUW, respectively. The SMSUW is somewhat pipe-like in shape, oriented vertically within the peridotite. The SMSUE is more tabular in aspect, extending eastwards from the central core of the deposit, again, at roughly the same orientation as the host intrusion. Although these units are distinguished from one another for the purposes of geological interpretation and Mineral Resource estimation, the SMSU bodies do appear to be a single contiguous mass.

A single irregular body of massive sulphide (MSU) occupies the central portion of the deposit, more or less between the SMSUE and SMSUW. The MSU extends outside of the semi-massive bodies, and in many cases has intruded the sedimentary rocks adjacent to the peridotite. This has resulted in several flat sill-like protuberances at the margin of the deposit.

Eagle East
Eagle East has identified nickel and copper rich massive and semi-massive sulphide mineralization concentrated along a horizontal conduit at the bottom of the main Eagle East intrusion. Prior to the exploration program initiated in 2013, no semi-massive sulphide had been found at Eagle East and MSU lenses of only one-to-two meters have been found along the 45° plunging keel of the intrusion. The Eagle East intrusion can be categorized into two components: the funnel shaped upper peridotite intrusion outlined prior to 2013 and the sub-horizontal conduit zone defined since 2013.

The conduit zone contains massive sulphide and semi-massive sulphide similar to Eagle, whereas the main intrusion consists of barren peridotite with low grade disseminated and thin massive sulphides along the keel. The conduit exploration program has identified a 500 m long horizontal section of the Eagle East feeder conduit, where the peridotite conduit is cored by semi-massive sulphide with massive sulphide accumulations at its base, as well as massive sulphide sills into the sediments. The conduit is up to 30 m thick, and its vertical extent is in the order of 75 m.

Mineralizing System
Sulphides are deposited as dense droplets in the primary magma due to decreased flow rate in the magma, or a change from laminar to turbulent flow due to changes in the conduit geometry. Multiple pulses likely occur in the same plumbing system, resulting in three discrete mineralization types which typically have hard contacts. The mineralizing intrusion is Mineralized Peridotite (MPER), which transports sulphides within large volumes of magma, and in this way is able to transport significant quantities of dense sulphides upward through the crust in a diluted form. This results in the conduits between mineralized zones consisting of barren peridotite or weakly mineralized peridotite, such as the upper zone of Eagle East.

Typical mineralization zoning at both Eagle and Eagle East consists of a mineralized peridotite conduit with a core of SMSU and a base of crosscutting MSU that also sills out into the surrounding sediments.

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Mining Methods

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Comminution

Crushers and Mills

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Processing

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Production

CommodityUnits2024202320222021202020192018201720162015
Nickel t  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe13,49417,57322,08124,11427,167
Copper t  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe14,29717,97421,30223,41724,331
Silver koz  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe143158200223210
All production numbers are expressed as metal in concentrate. ^ Guidance / Forecast.

Operational metrics

Metrics202320222021202020192018201720162015
Daily ore mining rate  ....  Subscribe  ....  Subscribe
Plant annual capacity  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe700 kt700 kt700 kt700 kt700 kt
Ore tonnes mined  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe748 kt753 kt760 kt745 kt740 kt
Tonnes milled  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe747 kt754 kt754 kt748 kt746 kt
Daily milling capacity  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe
Daily processing capacity  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe2,000 t

Production Costs

CommodityUnits20242023202220212020201920182017
Credits (by-product) Nickel USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe -3.46 / lb   -3.56 / lb   -3.37 / lb  
Cash costs (sold) Nickel USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 6.3 / lb   4.57 / lb   4.3 / lb  
Cash costs (sold) Nickel USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 2.84 / lb **   1.01 / lb **   0.93 / lb **  
All-in sustaining costs (sold) Nickel USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 3.74 / lb **   1.84 / lb **   1.42 / lb **  
^ Guidance / Forecast.
** Net of By-Product.

Operating Costs

Currency2016
Total operating costs ($/t milled) USD 115.97  

Financials

Units20242023202220212020201920182017
Capital expenditures (planned) M USD  ....  Subscribe
Capital expenditures M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 41.9   45.8   39.5  
Sustaining costs M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 11.5   10   11.4  
Revenue M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 212.9   265.9   276.5  
Gross profit M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 36   74.2  
After-tax Income M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 26.3   44.4   10.9  

Heavy Mobile Equipment

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Personnel

Mine Management

Job TitleNameProfileRef. Date
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EmployeesContractorsTotal WorkforceYear
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Aerial view:

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