Australia

Iron Knob Mine

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Overview

Mine TypeOpen Pit
StatusActive
Commodities
  • Iron Ore
Mining Method
  • Truck & Shovel / Loader
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SnapshotIron Knob Mining Area (IKMA) includes the Iron Monarch and Iron Princess pits (East Princess and West Princess) and Monarch scree pits.

SIMEC Mining placed the IKMA operations into care and maintenance on 1 July 2018. A cutback to access ore towards the base of Iron Monarch Pit recommenced on 1 March 2022.

While areas of the IKMA was in a care and maintenance phase, SIMEC Mining was however the operations recovery and processing of low-grade stockpiles from Monarch Scree and waste rock dump's (WRD’s).

Owners

SourceSource
CompanyInterestOwnership
Gupta Family Group ("GFG") Alliance 100 % Indirect
SIMEC Mining (operator) 100 % Direct
Tenement holder and operator - OneSteel Manufacturing Pty Ltd (operating as SIMEC Mining). SIMEC Mining is a business of OneSteel Manufacturing Pty Ltd which is a company in the GFG Alliance.

Contractors

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Deposit type

  • Banded iron formation
  • Metamorphic
  • Stratabound

Summary:

The Iron Knob mining area (IKMA) lies at the northern end of the Middleback Ranges (MBR).

• Hosted within the Palaeoproterozoic Hutchison Group metasediments.
• Mineralization is within the Lower Middleback Iron Formation grades upwards from Carbonate Haematite to Jaspilite Haematite facies.
• Ore Formation is considered through passive supergene enrichment of Magnetite Banded Iron Formations.
• Strongest Enrichment within the LMIF Carbonate Facies – leading to complete replacement of carbonates in highest grade zones.
• The Metasediments have a history of complex deformation dominated by East – West compression.
• Mineralised zones are bounded to the East and West regional scale North – South Shear Zones.
• Multiple Stages of Archean amphibolite dykes cross cut both deposits and are influence on mineralisation and Geotechnical Parameters.

Middleback Ranges Hematite
Hematite in the MBR occurs as stratabound Palaeoproterozoic deposits of the Lower Middleback Iron Formation (LMIF), part of the Hutchison Group. The Hutchison Group forms part of the Cleve Subdomain of the Gawler Craton, and lies on its western edge. The Cleve Subdomain comprises tightly folded high-grade metamorphic rocks that are mainly derived from marine shelf sediments and mafic and acidic volcanics (Parker, 2012b).

Middleback Ranges Framework In the MBR, the Hutchison Group is composed of the Warrow Quartzite and the Middleback Subgroup. However, the Warrow Quartzite is not identified at all locations. The Middleback Subgroup comprises the Katunga Dolomite, the LMIF, the Cook Gap Schist and the Upper Middleback Iron Formation (UMIF). The LMIF hosts the Middleback Ranges hematite deposits.

Ore Genesis
MBR iron ores formed through supergene enrichment; the process selectively dissolved waste minerals and replaced them with iron ore mineralisation. Preferential enrichment occurred in carbonate facies iron formation, dolomitic marble and to a lesser degree silicate facies iron formation. The silicates were much less soluble than the carbonates, and resulted in patchy mineralisation in the silicate iron facies (Yeates 1990).

Magnetite was recrystallised and remobilised during a period of metamorphism and deformation. Multiple periods of uplift, erosion and weathering resulted in the oxidation of magnetite to hematite and martite through supergene processes. Iron ore formation requires the movement of fluids through the rock. Most deposits (apart from Iron Queen and Iron Chieftain) lie on the western side of the range, adjacent to a major fault or mylonite zone along the western edge of the range, which may have provided this pathway. The process was most intense where the dolomite and carbonate facies were thickened and then subsequently exposed during the supergene process (Yeates 1990). Iron Queen and Iron Chieftain lie on the east side of the range in similar geology; their geneses are thought to be similar.

Iron Monarch deposite Local Geology
• Ore is contained within a synformal keel.
• Hematisation is pervasive and typically massive, extending to +400m depth.
• Mineralisation is bounded to the West by the West Wall Shear zone and Sleaford Granit.
• Bounded to the East by the East Wall Shear and Hiltaba Granite and volcanics at depth.
• Key influences and controls on Slope stability of the North Wall and Mineralisation are the “Older” amphibolite dyke and “Younger” dolerite dykes.

Iron Princess deposite Local Geology
• Consists of 2 ore bodies – Eastern Orebody and Western Orebody.
• Eastern Orebody – 2 Lenses that vary in thickness from 6 to 30m, typically brecciated and powdery in nature consisting dominantly of haematite and goethite.
• Western Orebody – Moderate to steeply dipping multiple lenses, between 5 and 20m in thickness.
Ore is dominantly heamatite.
• Un conformably overlain by the unconsolidated “Princess Beds” in which small detrital channel ores exists.
• Bounded to the West by the Western Shear Zone and to the East by the Iron Knob Mylonite zone.

Scree Deposits
Hematite in the MBR occurs as stratabound Palaeoproterozoic deposits of the Lower Middleback Iron Formation (LMIF), part of the Hutchison Group. The Hutchison Group forms part of the Cleve Subdomain of the Gawler Craton, and lies on its western edge (Figure 3). The Cleve Subdomain comprises tightly folded high-grade metamorphic rocks, mainly derived from marine shelf sediments and mafic and felsic volcanics.

As in the IBMA, substantial economically minable scree ore deposits have been identified around the flanks of the iron ore pit. These breccias and scree have partially weathered to clay however, cementation of the breccias has produced relatively geotechnically competent units.

Exploration at the proposed scree deposits is yet to be completed. Based on previous investigations of scree deposits within the MBR, the scree at Iron Monarch is likely to consist of the following geological materials  Jaspilite,  Ferruginous scree,  Maghemite,  BIF,  Clays,  Calcrete.

Limonite and goethite have also been noted in highly oxidised scree units within the MBR. Scree can be cemented (with carbonates) and can also contain pisolites; these are rounded gravels where each pisolite displays concentric layers of iron rich minerals, commonly hematite.

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

CommodityUnits2023202220212020
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All production numbers are expressed as lump & fines. ^ Guidance / Forecast.

Operational metrics

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^ Guidance / Forecast.

Production Costs

Commodity production costs have not been reported.

Heavy Mobile Equipment

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Personnel

Mine Management

Job TitleNamePhoneEmailProfileRef. Date
....................... Subscription required ....................... Subscription required ........... Subscription required ........... Subscription required Subscription required Oct 4, 2023
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....................... Subscription required ....................... Subscription required Subscription required Sep 19, 2023
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Aerial view:

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