Overview
Stage | Pre-Feasibility |
Mine Type | Underground |
Commodities |
|
Mining Method |
- Block caving
- Sub-level caving
|
Mine Life | 10 years (as of Jan 1, 2021) |
Definitive feasibility study for underground mining in North Pit commenced in 2022 with the location of the extraction level being modelled after the completion of the North Pit Stage 7 open pit mining. Additional drilling to the north, revisions to geotechnical models were completed and further exploration is planned as part of the DFS in 2023. |
Source:
p. 28
Grange Resources Ltd. indirectly owns 100% interest in the Savage River mine through it's wholly owned subsidiary Grange Resources Tasmania Ltd.
Contractors
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Summary:
The Savage River Magnetite deposit lies within and near the eastern margin of the Proterozoic Arthur Metamorphic Complex in north-western Tasmania. This complex is exposed along a northeast-southwest trending structural corridor, The Arthur Lineament, which separates Proterozoic sedimentary rocks to the northwest from a variety of Paleozoic rocks to the southeast (Turner 1990). These Paleozoic rocks include some major mafic and ultramafic intrusive complexes which lie just to the east of Savage River.
The magnetite orebodies are enclosed within a highly sheared and strike faulted belt of mafic and ultramafic schists and mylonite. This belt is 0.5km wide, strikes North-north-east to south-south-west, and is enclosed in a thick sequence of quartz-white mica schist (Whyte schist). Magnetite ore is almost entirely confined within ultramafic rocks, specifically serpentinite and talc-carbonate schist. These ore-bearing ultramafic rocks are exposed in an axial zone above the belt, ranging from about 40 to 100m wide and termed the Main Ore Zone. They also form rare, much narrower (mostly <20m wide) lenses and layers in the mafic sequence to the west.
Magnetite ore ranges from disseminated to massive, with much of the main Ore Zone comprising massive to semi-massive magnetite form 1994 Thornett report on structural and lithological mapping of North Pit and South Lens.
The Savage River ore-bodies occur discontinuously over a strike length of 6km with th ........

Mining Methods
- Block caving
- Sub-level caving
Summary:
The PFS considered the underground mining methods of block caving (BC) and sublevel caving (SLC). In addition, a Scavenge Mine was designed to recover the ore left in the walls of the North Pit. The Scavenge mine uses the SLC mining method. Non-caving mining methods were not considered in the PFS as they had been ruled unfavourable during earlier concept studies due to higher mine operating costs.
The Exploration Decline has been constructed and provides a platform to access the Scavenge mine. The Scavenge mine commences above the pit floor and does not require extensive dewatering infrastructure for first production and provides access to ore remaining at the margins around the pit. This provides early production while the decline is progressed to the undercut and extraction levels.
The target annual underground mining production rate is limited by the capacity of the pipeline that delivers concentrate slurry from the mine to the pellet plant in Port Latta. Underground development for both the BC and SLC mining options is based on extending and expanding the existing exploration decline development.
The BC will operate with a maximum of 7 loaders feeding 4 truck loading stations. 6 trucks will be utilised to feed the underground crusher, delivering approximately 500,000 tonnes per month of ore to the surface run-of-mine stockpile.
The BC designs and schedules are based on the following design criteria:
• Extraction level ........

Source:
Flow Sheet:
Summary:

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Projected Production:
Ore grade is expressed as Davis Tube Recovery (DTR%).
Commodity | Product | Units | LOM |
Iron (magnetite)
|
Pellets
|
Mt
| 24 |
Iron (magnetite)
|
Concentrate
|
kt
| 25,000 |
Operational Metrics:
Metrics | |
Annual ore mining rate
| ......  |
Ore tonnes mined, LOM
| ......  |
* According to 2021 study.
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Reserves at December 31, 2022:
Mineral Resources estimates above a cut-off grade of 15% Davis Tube Recovery (DTR%).
Category | Tonnage | Commodity | Grade |
Proven
|
47.4 Mt
|
DTR
|
51.1 %
|
Proven
|
47.4 Mt
|
Iron
|
67.8 %
|
Probable
|
18.1 Mt
|
DTR
|
40.1 %
|
Probable
|
18.1 Mt
|
Iron
|
67.2 %
|
Proven & Probable
|
65.5 Mt
|
DTR
|
48.1 %
|
Proven & Probable
|
65.5 Mt
|
Iron
|
67.7 %
|
Measured
|
126 Mt
|
DTR
|
53.6 %
|
Measured
|
126 Mt
|
Iron
|
67.8 %
|
Indicated
|
76.1 Mt
|
DTR
|
39.2 %
|
Indicated
|
76.1 Mt
|
Iron
|
67.7 %
|
Inferred
|
37.7 Mt
|
DTR
|
36.7 %
|
Inferred
|
37.7 Mt
|
Iron
|
68 %
|
Total Resource
|
239.8 Mt
|
DTR
|
46.4 %
|
Total Resource
|
239.8 Mt
|
Iron
|
67.8 %
|
Commodity Production Costs:
| Commodity | Average |
C1 cash costs
|
Iron (magnetite)
|
......
|
Assumed price
|
Iron (magnetite)
|
......
|
* According to 2021 study / presentation.
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Operating Costs:
| Units | 2021 |
UG mining costs ($/t milled)
|
AUD
| 22 * |
* According to 2021 study.
2021 Study Costs and Valuation Metrics :
Metrics | Units | LOM Total |
Pre-Production capital costs
|
$M AUD
|
......
|
Sustaining CapEx
|
$M AUD
|
......
|
Total OpEx
|
$M AUD
|
......
|
Gross revenue (LOM)
|
$M AUD
|
......
|
Pre-tax Cash Flow (LOM)
|
$M AUD
|
......
|
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Corporate Filings & Presentations:
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