Overview
Stage | Construction |
Mine Type | Open Pit & Underground |
Commodities |
|
Mining Method |
- Truck & Shovel / Loader
- Longhole open stoping
|
Processing |
- Gravity separation
- Smelting
- Carbon re-activation kiln
- Agitated tank (VAT) leaching
- Carbon in leach (CIL)
- AARL elution
- Carbon adsorption-desorption-recovery (ADR)
- Solvent Extraction & Electrowinning
|
Mine Life | 7 years (as of Jan 1, 2020) |
Latest News | Tulla Resources Plc: Iron ore offtake deal for Norseman Gold Project July 1, 2022 |
Source:
p. 4
In May 2019 Tulla Resources Plc and its wholly owned subsidaries, Central Norseman Gold Corporation Pty Ltd (CNGC Pty Ltd) and Pangolin Resources Pty Ltd entered into a Farm-In and Joint Venture Agreement with Pantoro Limited and its wholly owned subsidiary, Pantoro South Pty Ltd (collectively Pantoro) (FJVA) whereby Pantoro acquired a 50% interest in the Norseman Gold Project.
Pantoro has management control of the site, and mineral and mining tenements.
The tenement where the MRE has been completed is 50% held by Pantoro subsidiary company Pantoro South Pty Ltd in an unincorporated JV with CNGC Pty Ltd.
Summary:
The project area lies at the southern extent of the Norseman - Wiluna Greenstone Belt of the Eastern Goldfields Province of the Yilgarn Block, Western Australia. The regional geology of the Norseman area has been subdivided into four formations being the Penneshaw Formation, Noganyer Formation, Woolyeenyer Formation and the Mt Kirk Formation.
The oldest unit is the Penneshaw Formation which has been dated at 2938±10 Ma (U-Pb zircon, (Hill et al., 1992). The western part of this unit is dominated by amphibolite with minor sediment and felsic rocks, whereas the eastern part comprises intercalated amphibolite and highly deformed felsic rocks.
The overlying Noganyer Formation consists of sediment iron formation (jaspilite), siltstone and sandstone, and minor carbonaceous shale.
Overlying the Noganyer Formation with a conformable or gently unconformable contact is the Woolyeenyer Formation. The Woolyeenyer Formation is dominated by mafic volcanic rocks with minor conformable ultramafic units and sediment bands. These rocks are intruded by mafic dykes with a dominant northeast to northwest trend that are interpreted to be syn-volcanic. The Woolyeenyer Formation is regarded as unconformably overlain by sedimentary and felsicvolcanic to volcaniclastic rocks of the Mt Kirk Formation that have been intruded by thick, differentiated mafic sills. The contact between these units is marked by the regionally extensive Abbottshall Chert comprising silicified banded and fine-grained sediment.
Intrusive rocks in the Norseman region include the Buldania granite, which intrudes the Penneshaw Formation; the Pioneer Granite and similar poorly exposed domal granites that intrude the sequence along the western margin of the greenstone belt; felsic porphyry to granitoid dykes intrude all units and predate mineralisation, and Proterozoic mafic dykes that occupy a Yilgarn-wide set of linear brittle fractures.
All the Norseman reefs are typical Archean lode systems and the orebodies are almost completely structurally controlled. They all share common features which indicates their genesis:
1.Most of the high grade ore zones occur where veins intersect ‘gabbro’ intrusions, and specific oriented contacts are particularly favourable. This is most likely a result of competency contrasts which allow preferential propagation of cracks and other openings within the coarser grained rocks, and the amount of veining is controlled by the orientation of the contact relative to stress directions.
2.Zones where NNE- and west-dipping felsic, dacitic porphyries are intersected by the reefs tend to be zones of intense structural complexity and gold grades are even more variable than usual. In some reefs these can be zones of high grades, and in others, low grades. This reflects the geometry relative to the local direction of maximum compression, and therefore whether the structures are tight or open.
3.Most reefs have only very narrow (a few metres at most) alteration selvages. In some cases, these selvages host high gold grades but in all cases the grade drops off very quickly away from the quartz vein. The northern deposits usually have wider alteration haloes caused by more reaction of ore fluids with host rocks (Archer and Turner, 1998)
Mining Methods
- Truck & Shovel / Loader
- Longhole open stoping
Summary:
Life of Mine Plan
The Phase One DFS Life of Mine (LOM) mines and processes 5.9 Mt of ore of which 4.8 Mt is Ore Reserve and 1.1 Mt is Inferred Mineral Resources. 25% of the total Ore Reserve remains unmined and available for future production at the end of the Phase One DFS LOM.The Inferred Mineral Resources have had modifying factors applied in the same manner as the Ore Reserve. There is a low level of geological confidence associated with Inferred Mineral Resources and there is no certainty that further exploration work will result in the determination of Indicated Mineral Resources or that the production target itself will be realised.
Mining Schedule
Pantoro has utilised a very conservative approach to mine scheduling for the purposes of the DFS. All ore mined is assumed to be stockpiled and processed equally with no discrimination between high grade and low grade ore. In practice, higher grade ore will be transported to the ROM with low grade ore stockpiled at the mine until required for processing.As additional ore sources are added in subsequent stages of Mineral Resource and Ore Reserve definition, new high grade ore sources will replace low grade stocks assumed to be mined.
Mine Design
The large open pits to be excavated at Scotia, Gladstone, and Cobbler have been designed in stages to maximise open pit ore feed throughout the project life. Other open pits have been designed to be excavated in a single stage.
Mine designs were completed based on the optimised shell for each area, and mine physicals and costs are scheduled on a monthly basis. A summary of the major open pit areas is provided below.
Scotia (South Mining Centre)
Scotia open pit mining centre is staged as three contiguous pits (North, Central and South). The final pit shell is 1,150 metres long and extends to a depth of 150 metres below surface. The open pit design was based on recommendations made by the DFS geotechnical consultants Peter O’Bryan and Associates.
Gladstone (North Mining Centre)
The Gladstone open pit mining centre is staged as a progressive cutback of the Gladstone-Everlasting orebody from south to north. The final pit shell is 1,550 metres long and extends to a depth of 100 metres below surface. The staging of the open pit allows for progressive dewatering and incorporates geotechnical design recommendations provided by DFS geotechnical consultants Peter O’Bryan and Associates.
Cobbler (North Mining Centre)The Cobbler open pit mining centre is staged as a central starter pit to target the high grade core of the ore body followed by a large cutback of the starter pit to recover the remainder of economic mineralisation. The final open pit shell is 620 metres long and extends to a depth of 80m below surface. The open pit design was based on recommendations made by the DFS geotechnical consultants Peter O’Bryan and Associates.
Open Pit Mining Schedule
Mining has been scheduled to minimise pre-production capital while maintaining operational efficiency and processing plant ore feed. The open pit mining schedule commences with pre-stripping at Cobbler and Scotia approximately three months prior to the commencement of processing. While Cobbler is lower grade than Scotia and Gladstone, the pit provides easy access to bulk ore tonnes with a low strip ratio. Selection of Cobbler as a feed source at commencement of operations reduces total capital exposure and payback times while ensuring that a large ore stock pile is in place from the start of operations.
Underground Mining Schedule
Underground mining in Phase One is primarily from the OK Underground Mine in the early phases of project development, with underground mining at Scotia and St Patricks to commence following completion of Phase One of open pit mining operations.
OK Underground Mine
The extensive existing infrastructure at the OK Underground Mine facilitates a rapid restart schedule with limited capital outlay. The existing underground development infrastructure is in good condition with multiple levels developed and accessible for production.
The major pre-production capital activity is excavation of a ventilation rise from the surface to the base of the existing workings to reduce ventilation operating costs over the life of the mine. Once the ventilation rise is established, production activities from already developed ore blocks can commence immediately. A small amount of dewatering and capital rehabilitation is required at the base of the decline to access the new reserve blocks below the workings. Due to the sub vertical nature of the orebody, rock mass characteristics and modified stope stability analysis, long hole open stoping was selected as the most suitable mining method.
Scotia Underground Mine
Scotia Underground is scheduled to start following completion of the North and South stages of open pit mining. Two separate portals will be established, one to the North and one to the South, to allow decline development to access the corresponding portion of the Ore Reserves beneath the final open pit shell.
St Pats Underground Mine
St Pats underground mine forms part of the iconic Mainfield at Norseman. Review of existing data by Pantoro identified St Pats as an immediate opportunity without the need for extensive drilling as the data in place is adequate for estimation of the Mineral Resource and Calculation of an initial Ore Reserve. Additional drilling at St Pats will be undertaken in the Phase Two Resource Development drilling program with the objective of substantially increasing the mining inventory before the commencement of development.
Flow Sheet:
Crusher / Mill Type | Model | Size | Power | Quantity |
Jaw crusher
|
|
|
|
1
|
Cone crusher
|
|
|
|
2
|
Ball mill
|
|
|
|
1
|
Summary:
BOOT operation for crushing circuit
The study identified the crushing circuit as being suitable for operation using a Build-Own-Operate–Transfer model. The contractor will construct own and operate the crushing circuit for the first three years of operation, with transfer of asset ownership following a balloon payment at the end of the third year of operation. During the life of the BOOT contract, the contractor is responsible for the operation, maintenance and cost of the crushing circuit from the primary crusher ore feed to the fine ore stockpile discharge. Operating under the BOOT model reduces Pantoro’s operational risk and ensures optimal plant configuration before taking ownership. The capital payment at the end of the three year BOOT contract is $1.8 million. All costs associated with the BOOT contract are included in the DFS cost estimate.
•A crushing circuit comprising of a primary jaw crusher, crushed ore stockpile, crushed ore reclaim, a multi-deck crushed ore screen operating in closed circuit with both a secondary and a tertiary cone crusher, producing a -10 mm product.
•A milling circuit comprised of a ball mill operating in closed circuit with cyclones to produce a grind size P80 of 75 µm.
Processing
- Gravity separation
- Smelting
- Carbon re-activation kiln
- Agitated tank (VAT) leaching
- Carbon in leach (CIL)
- AARL elution
- Carbon adsorption-desorption-recovery (ADR)
- Solvent Extraction & Electrowinning
Flow Sheet:
Summary:
A key design criteria for the processing plant was flexibility to treat multiple ore sources from both the Stage 1 operations and from additional ore sources likely to be accessed through subsequent phases of resource development.
Due to the high likelihood that multiple ore sources will be utilised to feed the processing plant over the life of mine, it was determined that the best strategy was to design the processing plant to grind one million tonnes per annum at p80 75µm for the Phase One ore blend. This design allows processing of one million tonnes per annum of the hardest feed source (Scotia) at a grind size of p80 106µm, or 0.8 million tonnes per annum at 75µm providing maximum flexibility to operations.
• Gravity concentration and removal of coarse free gold from the milling circuit and treatment of gravity concentrate by an intensive leach reactor, followed by a dedicated electrowinning circuit.
Recoveries & Grades:
Commodity | Parameter | Avg. LOM |
Gold
|
Recovery Rate, %
| 95 |
Gold
|
Head Grade, g/t
| 3.2 |
Projected Production:
Commodity | Units | Avg. Annual | LOM |
Gold
|
oz
| 108,000 | 579,459 |
All production numbers are expressed as metal in doré.
Operational Metrics:
Metrics | |
Ore tonnes mined, LOM
| ......  |
Tonnes processed, LOM
| ......  |
Annual processing rate
| ......  |
Annual processing capacity
| ......  |
* According to 2020 study.
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Reserves at October 12, 2020:
The global gold Mineral Resource has been reported at a 0.7 g/t gold cut-off for material within 150m of topographic surface and 2.0 g/t gold for material greater than 150m of topographic surface being based upon economic parameters and depths (within 220 m of topographic surface) currently utilised at Pantoro’s existing operations, where deposits of the same style, commodity, comparable size and mining methodology have been extracted.
Category | Tonnage | Commodity | Grade | Contained Metal |
Proven
|
4,165 kt
|
Gold
|
0.8 g/t
|
100 koz
|
Probable
|
4,895 kt
|
Gold
|
3.2 g/t
|
502 koz
|
Proven & Probable
|
9,060 kt
|
Gold
|
2.1 g/t
|
602 koz
|
Measured
|
4,572 kt
|
Gold
|
1.6 g/t
|
234 koz
|
Indicated
|
13,871 kt
|
Gold
|
3.9 g/t
|
1,721 koz
|
Inferred
|
16,570 kt
|
Gold
|
4.3 g/t
|
2,280 koz
|
Total Resource
|
35,000 kt
|
Gold
|
3.8 g/t
|
4,241 koz
|
Corporate Filings & Presentations:
Document | Year |
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2021
|
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2020
|
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|
2020
|
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News:
Aerial view:
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