Overview
Stage | Production |
Mine Type | Open Pit |
Commodities |
|
Mining Method |
- Truck & Shovel / Loader
- Open stoping
|
Processing |
- Gravity separation
- Smelting
- Filter press plant
- Carbon in leach (CIL)
- AARL elution
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
|
Mine Life | 14 years (as of Jan 1, 2018) |
Based on the feasibility study recently completed, Ravenswood is undertaking a development plan that will increase gold production from 60,000 oz pa. to over 200,000 ounces p.a. paving way for it to be the largest gold producer in Queensland. |
Latest News | Ravenswood expansion going for Olympic gold November 15, 2021 |
Source:
p. 1
Resolute Mining has completed the sale of the Ravenswood gold mine in Queensland to a Specialist resources private equity manager, EMR Capital (“EMR”), and Golden Energy and Resources Limited (“GEAR”), (collectively “the EMR GEAR Consortium”) on 31 March 2020.
Golden investments (Australia) II Pte. Ltd., a wholly-owned subsidiary of GEAR entered into a joint venture (the “Joint Venture”) with Raven Gold Nominee Pty Ltd (as trustee on behalf of investors managed or advised by EMR Capital) (together with its affiliates, “EMR”) to establish a joint venture company, Ravenswood Gold Group Pty Ltd (previously known as Mining Gold Group Pty Ltd) (“Topco”), to acquire the Ravenswood gold mine from Carpentaria Gold Pty Ltd (“Carpentaria Gold”) and its parent company, Resolute Mining Limited.
Deposit Type
- Breccia pipe / Stockwork
- Footwall hosted
- Vein / narrow vein
Summary:
Mineralisation occurs in variably orientated tabular sulphide – quartz veins and mineralised shear zones and in numerous vein stock works. Areas of weak veining separate the more strongly stock-worked areas into discrete zones. Individual veins can vary in width from hairline fractures up to one metre locally. Mineralisation extends from the topographic surface and has been confirmed to extend at depth in deep drilling. The mineralisation remains open at depth.
The Jessop Creek Tonalite, an Early to Middle Devonian age unit of the Ravenswood Batholith, hosts the mineralisation. In the project area the Jessop Creel Tonalite can be divided into diorite, quartz diorite and minor gabbro. Boundaries between these units vary from sharp to indistinct and often show complex relationships including stoping xenoliths and irregular dykes. No association between the host lithology and the gold mineralisation has been established other than it is a suitable competent host that allowed the cross cutting sulphide veins to develop.
Buck Reef West / Sarsfield-Nolans Deposit lies within the northern part of the Thomson fold belt which forms part of the Charters Towers province, in a tight cluster of calc-alkaline intrusives of Ordovician to Devonian age known as the Ravenswood Batholiths. Individual intrusive compositions vary from adamellite to diorite: - granite and granodiorite are the most common.
The Buck Reef West / Sarsfield gold deposit is located within and around the junction of three prominent fault systems. At each deposit weathered zone persists to an average of 15 metres below surface. Supergene effects are restricted to a discontinuous horizon within a partially oxidised zone less than 5 metres thick. At least 95% of gold is located within a network of flatly dipping sulphide-quartz veins. Movement on the faults has controlled dilation within the veins, and at least 17 different structural movements and alteration events have reactivated the vein. Veins (20mm to 250mm thick) are typically associated with a phyllic alteration selvedge up to 500mm wide. Vein mineralogy is sulphide dominant with quartz and calcite constituting the major gangue phases. Total sulphide content of the ore is less than 5% with the most common phases being pyrite, pyrrhotite, sphalerite and chalcopyrite. Gold occurs as mostly sub 50 micron free milling grains on fractures and sulphide mineral boundaries.
Geologically, the Buck Reef West and Sarsfield-Nolans resource modelling was divided into several domains based on geological structures/ lithologies and gold distribution. The Buck Reef West domain interpretation comprises a broad, moderately dipping envelope with a locally developed higher grade footwall zone which is cross cut y two sub-vertical north-northeast trending, commonly higher grade zones. They are named; Background, Main envelope – lower grade zone, Main envelope – higher grade footwall zone, Eastern vertical zone and Western vertical zone. The Sarsfield–Nolans area mineralised domains comprise a main moderately northerly dipping envelope representing the general Sarsfield-Nolans trend, and several variably oriented and cross-cutting zones in the Sarsfield area. They are named; East background, Main envelope, Bell zone, Keel zone, Buck Reef trend and West background.
The Sarsfield deposit outcrop over a 900 by 900 metre area with mineral resources defined to a depth of approximately 650 metres below pre-mining land surface. The Nolans deposit extends in an eastward direction from the Sarsfield deposit for 1.7 kilometres with mineral resources estimated to a depth of 330 metres below pre-mining land surface. The Buck Reef deposit is centred 500 metres south west of Sarsfield deposit and outcrops over an area of 500 by 800 with mineral resources defined to a depth of approximately 600 metres.
Mining Methods
- Truck & Shovel / Loader
- Open stoping
Summary:
Mining methods for the extraction of gold at Buck Reef West and Sarsfield-Nolans has primarily been by open pit and underground methods. It is anticipated that large scale open pit mining methods will be applied for the remaining resources. Grade control of mining blocks will be based on sampling from high quality reverse circulation drilling spaced at approximately 5mE by 12.5mN with samples taken at 1.5 metre intervals down-hole.
The Buck Reef West and Sarsfield pits were mined historically using routine open pit mining methods with a backhoe type excavator to excavate benches. Beneath the open cut, open stope underground mining methods were used historically dating back to 1870.
Historically, (1870-1918) + recent (1987-2005) production, totaled around 400koz of high grade gold.
A minimum mining width of 30m has been applied. Ramp widths are set at 30m (double lane – 180 t rear dump truck), with narrower single lane ramps (16m wide) for the bottom 40m of the pit design.
Existing geotechnical parameters, used in previous mining and validated through external consultant studies as part of the Feasibility have been applied which include:
Oxide – Single 10m bench height with a batter face angle of 60o and berm width of 8m.
Fresh - Double stacked 10m high benches (20m overall height) with a batter face angle of 80o and 7m berm width.
Crusher / Mill Type | Model | Size | Power | Quantity |
High Pressure Grinding Rolls (HPGR)
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SAG mill
|
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Ball mill
|
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Summary:
The crushing circuit at the Nolans Plant treating Buck Reef West and Sarsfield-Nolans ore will use either two or three stage crushing depending on the gold grade of the material being delivered.
The recent Strategic Review incorporated the use of High Pressure Grinding Rolls (HGPR) to reduce the nominal particle size fed to the milling circuit, thus increasing the nominal plant throughput from 5.0 Mtpa to 6.8 Mtpa.
Processing
- Gravity separation
- Smelting
- Filter press plant
- Carbon in leach (CIL)
- AARL elution
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
Source:
Summary:
Gold is recovered using crushing, milling (SAG + ball), gravity circuit (Knelson Concentrator), and a CIL circuit.
Gold is recovered from loaded carbon in a four tonne capacity AARL elution plant. Gold is then deposited on to stainless steel cathodes in an electrolytic circuit.
Gold will be poured into dore bars, containing approximately 80% gold and 20% silver. The dore bars are sent to the Perth Mint for refining.
Processing of the tailings will comprise thickening and filtering to provide a residue or filter cake which can be dry stacked. The tailings will be placed with conventional earth moving equipment to shape the final landform and gradient with surface compaction completed with smooth drum rollers.
Recoveries & Grades:
Commodity | Parameter | 2020 | 2019 | 2018 | 2017 | 2016 |
Gold
|
Head Grade, g/t
| ......  | ......  | 1.19 | 1.54 | 2.05 |
Gold
|
Recovery Rate, %
| ......  | ......  | 94.4 | 93.1 | 94.3 |
Production:
Production for 2020 is reported for the period 1 Apr 2020 to 31 Dec 2020.
Commodity | Units | 2020 | 2019 | 2018 | 2017 | 2016 |
Gold
|
koz
| ......  | ......  | 90 | 92 | 106 |
All production numbers are expressed as metal in doré.
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Operational Metrics:
Metrics | 2020 | 2019 | 2018 | 2017 | 2016 |
Annual processing capacity
| ......  | | | | |
Ore tonnes mined
| ......  | 290,437 t | 2.46 Mt | 2.37 Mt | 1.31 Mt |
Tonnes milled
| ......  | 2,699,285 t | 2.45 Mt | 2 Mt | 1.7 Mt |
Annual milling capacity
| ......  | | 2.8 Mt | 2.8 Mt | |
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Reserves at December 31, 2020:
Mineral Reserves and Resources are reported at cut-off grade of 0.3 g/t Au.
Category | Tonnage | Commodity | Grade | Contained Metal |
Proven
|
34 Mt
|
Gold
|
0.7 g/t
|
700 koz
|
Probable
|
81 Mt
|
Gold
|
0.7 g/t
|
1,900 koz
|
Proven & Probable
|
115 Mt
|
Gold
|
0.7 g/t
|
2,600 koz
|
Measured
|
32.2 Mt
|
Gold
|
0.7 g/t
|
740 koz
|
Indicated
|
96.5 Mt
|
Gold
|
0.8 g/t
|
2,346 koz
|
Inferred
|
48.6 Mt
|
Gold
|
0.6 g/t
|
876 koz
|
Total Resource
|
177.3 Mt
|
Gold
|
0.7 g/t
|
3,961 koz
|
Commodity Production Costs:
| Commodity | Units | 2020 | 2019 | 2018 | 2017 | 2016 |
Credits (by-product)
|
Gold
|
AUD
|
|
......
|
-9 / oz
|
|
|
Cash costs
|
Gold
|
USD
|
|
......
|
1,019 / oz
|
943 / oz
|
752 / oz
|
All-in sustaining costs (AISC)
|
Gold
|
AUD
|
......
|
|
|
|
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All-in sustaining costs (AISC)
|
Gold
|
USD
|
|
...... †
|
1,071 / oz†
|
1,059 / oz†
|
892 / oz†
|
† Net of By-Product.
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Financials:
| Units | 2020 | 2019 | 2018 | 2017 | 2016 |
Capital expenditures
|
M AUD
| | | 21.2 |
13.8
|
6.6
|
Revenue
|
M AUD
| | ......  | 138.5 |
158
|
180.4
|
Operating Income
|
M AUD
| ......  | | |
|
|
After-tax Income
|
M AUD
| ......  | | 9.9 |
15.2
|
21.7
|
EBITDA
|
M AUD
| | | 11.7 |
24
|
49.8
|
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Proposed Heavy Mobile Equipment as of July 22, 2019:
HME Type | Size |
Excavator
|
|
.......................
|
.......................
|
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Corporate Filings & Presentations:
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News:
Aerial view:
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