Overview
Stage | Construction |
Mine Type | Open Pit |
Commodities |
|
Mining Method |
|
Processing |
- Smelting
- Agitated tank (VAT) leaching
- Carbon in column (CIC)
- Elution
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
|
Mine Life | 2.5 years (as of Jan 1, 2021) |
Mining is already underway. Mt Freda ore to be processed on-site at Vat Leach CIC Processing Plant – construction is underway. Production is scheduled for Q3, CY2022. |
Latest News | Tombola on fast track to gold production June 21, 2022 |
Source:
p. 11
Company | Interest | Ownership |
Queensland Mining Corp Ltd.
|
20 %
|
Indirect
|
Tombola Gold Ltd.
|
80 %
|
Indirect
|
The mining leases ML2741, ML2742, ML2750, ML2752, ML2763 & EPM14163 are owned 100% by Spinifex Mines Pty Ltd. Ausmex Mining Group Limited owns 80% of Spinifex Mines Pty Ltd. Queensland Mining Corporation Limited owns 20% of Spinifex Mines. Mt Freda comprises mining leases ML2741 and ML2752.
Ausmex Mining Group Limited change the name of the Company to Tombola Gold Ltd.
Deposit Type
- Vein / narrow vein
- Epithermal
Summary:
The mineralisation at Mt Freda is concentrated in a west-northwest trending outcropping fault gouge extending over a length of about 600 metres, that dips steeply to the south. Geophysical surveys correlate with outcropping geology and indicate that a conductive feature runs approximately 2,000m under cover from within the Mt Freda pit, to the north west into EPM14163. Gold mineralisation is located on the contact of the Mt Norna formation with the overlying Toole Creek Volcanics.
Drilling has defined the mineralisation to a depth of approximately 280 metres below surface, or about 220 metres below the floor of the existing open pit. The deposit lies in the Cloncurry district, which is characterised by Paleoproterozoic cover sequence rocks. Rock sequences in this zone are intruded by a number of metamorphic intrusions that are predominantly potassic in nature.
Mt Freda displays an epithermal style of mineralisation, potentially stemming from a deeper mafic source, as defined by Emeritus Professor Ken Collerson.
The mineralisation at Mt Freda is hosted in a volcano-sedimentary sequence predominately composed of basalts and sandstones. Mineralisation is not considered to be confined to a particular lithology.
The mineralisation at Mt Freda, indicated by elevated gold grades, appears to be structurally controlled and is associated with shearing, brecciation and quartz veining. The majority of the mineralisation forms a single lens dipping around 75° on average towards the SSW. This zone pinches out along strike in both directions but is open at depth.
Summary:
Mining will be by conventional open pit mining methods, with drill and blast followed by load and haul using backhoe excavators and haul trucks. Drilling and blasting will be performed on 10 m flitches and 20 m benches, as will loading of the blasted material. Where possible in the near-surface weathered zone, “free dig” mining will be carried out (i.e., without drilling and blasting). Ripping by bulldozer may also be employed in transitional to reduce the quantity of drilling and blasting required.
The envisaged scale of mining at the Mount Freda deposit is relatively small scale with a peak total material movement of approximately 825 ktpm (for a six-month duration). The annual processing plant feed requirement is approximately 0.3 Mtpa (25 ktpm).
Pushback 2 is a continuation of the Pushback 1 to final depth and will allow for continued plant feed during the increased stripping of the Pushback 3. Approximately 4.5 Mt of waste is required to be stripped in Pushback 3 prior to access to any substantive quantity of process feed.
To ensure plant throughput is maintained, additional equipment will need to be mobilised in Month 11 in order to increase the waste stripping capability of the fleet from 230 ktpm to 800 ktpm from Month 12 to Month 19, with an allowance of one month for ramp-up/ramp-down. The Pushback 3 steady state waste stripping rate thereafter is on average 430 ktpm. Failure to achieve the increased waste stripping requirements and timing will result in a process feed supply gap in the processing
plant. This is considered a materially high-risk extraction strategy.
Pit slope parameters for pit optimisation and pit design are based on geotechnical recommendations developed by AMEC (2021):
• Oxide material has bench height of 10 m, batter angle of 70 degrees, and berm width of 5 m;
• Fresh material has a bench height of 20 m, batter angle of 85 degrees, and berm width of 8 m.
A haul road width of 13 m has been used for all mine design.
Mining dilution of 10% has been applied to pit optimisations and production scheduling.
Mining recovery of 95% has been applied to pit optimisation and production scheduling.
A minimum mining width of 25 m has been applied to all mine design.
Flow Sheet:
Crusher / Mill Type | Model | Size | Power | Quantity |
Cone crusher
|
|
|
|
1
|
Processing
- Smelting
- Agitated tank (VAT) leaching
- Carbon in column (CIC)
- Elution
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
Flow Sheet:
Summary:
The ore from the mining at Mt Freda open cut, will be processed on site at Mt Freda using two 40,000 tonne reusable cyanide leach vat ponds with the capacity of processing +300,000 tonne per year. The cyanide leach vats, process ponds and the freshwater pond.
Recoveries & Grades:
Commodity | Parameter | Avg. LOM |
Gold
|
Recovery Rate, %
| 93.7 |
Gold
|
Head Grade, g/t
| 2.7 |
Projected Production:
RF 1 pit shell 36 was selected for the basis of the detailed pit design process.
Commodity | Units | LOM |
Gold
|
koz
| 57 |
All production numbers are expressed as metal in doré.
Operational Metrics:
Metrics | |
Stripping / waste ratio
| ......  |
Daily ore mining rate
| ......  |
Waste tonnes, LOM
| ......  |
Ore tonnes mined, LOM
| ......  |
Total tonnes mined, LOM
| ......  |
Plant annual capacity
| ......  |
Annual ore mining rate
| ......  |
* According to 2021 study.
- Subscription is required.
Reserves at February 28, 2021:
A cut-off grade of 0.5 g/t Au has been assumed to calculate potential open pit Mineral Resources above the 160 RL (around 120 m below the original topography). Below this level, a 1.0 g/t Au cut-off has been assumed for potential underground Mineral Resources.
Category | OreType | Tonnage | Commodity | Grade | Contained Metal |
Indicated
|
In-Situ (OP)
|
380,000 t
|
Gold
|
2.68 g/t
|
32,800 oz
|
Indicated
|
In-Situ (UG)
|
233,000 t
|
Gold
|
3.25 g/t
|
24,400 oz
|
Indicated
|
Total
|
613,000 t
|
Gold
|
2.91 g/t
|
57,300 oz
|
Inferred
|
In-Situ (OP)
|
143,000 t
|
Gold
|
2.24 g/t
|
10,300 oz
|
Inferred
|
In-Situ (UG)
|
250,000 t
|
Gold
|
2.29 g/t
|
18,400 oz
|
Inferred
|
Total
|
393,000 t
|
Gold
|
2.27 g/t
|
28,700 oz
|
Total Resource
|
In-Situ (OP)
|
524,000 t
|
Gold
|
2.56 g/t
|
43,200 oz
|
Total Resource
|
In-Situ (UG)
|
482,000 t
|
Gold
|
2.76 g/t
|
42,800 oz
|
Total Resource
|
Total
|
1,006,000 t
|
Gold
|
2.66 g/t
|
86,100 oz
|
Commodity Production Costs:
| Commodity | Units | Average |
Assumed price
|
Gold
|
USD
|
...... *
|
* According to 2021 study / presentation.
- Subscription is required.
2021 Study Costs and Valuation Metrics :
Metrics | Units | LOM Total |
Gross revenue (LOM)
|
$M AUD
|
......
|
Operating margin, %
|
|
......
|
Operating margin (LOM)
|
$M AUD
|
......
|
- Subscription is required.
Mine Management:
Job Title | Name | Profile | Ref. Date |
.......................
|
.......................
|
|
Jun 21, 2022
|
- Subscription is required.
Corporate Filings & Presentations:
Document | Year |
...................................
|
2021
|
...................................
|
2021
|
...................................
|
2021
|
...................................
|
2021
|
- Subscription is required.
News:
Aerial view:
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