Overview
Stage | Production |
Mine Type | Open Pit |
Commodities |
|
Mining Method |
|
Processing |
- Crush & Screen plant
- Gravity separation
- Carbon in leach (CIL)
- Cyanide (reagent)
|
Mine Life | 2028 |
The Duketon North Operations (“DNO”) comprises the Moolart Well, Gloster, Dogbolter, Petra and Anchor pits with all ore processed through the Moolart Well processing plant. |
Latest News | MACA receives contract extension from Regis Resources at Duketon North May 3, 2022 |
Source:
p. 87
Deposit Type
- Mesothermal
- Vein / narrow vein
- Intrusion related
Summary:
Moolart Well.
Moolart Well, as part of the DNO, is a mesothermal gold deposit hosted dominantly in intermediate diorite intrusives but also in dolerite, basalt and to some degree ultramafic rock types. Hypogene gold mineralisation is structurally controlled in fresh rock and to a lesser extent in oxidised rock. Competency contrasts between rock types are thought to pay a major role in providing the architecture in which mineralisation occurs. The gold is associated with multiple local moderate to steep east dipping N-S striking structures. These are offset by a series of NW- SE striking post to syn-mineralisation structures which are also partly mineralised.
Deflation and lateritisation of the extant profile are responsible for accumulating a significant portion of the Moolart Well mineralisation into the overlying transported laterite regolith. Remobilisation of gold in the weathered residual profile has depleted the upper parts of the clay zone and enhanced the gold grade of the lower part of the profile in the saprock zone.
A model of the lithology and weathering was generated prior to the mineralisation domain interpretation commencing. The mineralisation geometry has a very strong relationship with the lithological interpretation and structure in both the laterite and the oxide/fresh mineralisations. The updated Reserve for Moolart Well includes numerous open pits, including the addition of three new mining areas (Buckingham, Eindhoven and Mitchell).
Moolart Well is a blind gold deposit with several styles of gold occurring within the regolith profile. In transported regolith extending to 20m depth, a Laterite Ore Zone is defined by a coherent sub-horizontal gold blanket consisting of colluvial ironstone and pisolites in a clayey iron rich matrix. The Laterite Zone has an average thickness of 4m, extends over 5km N-S and 1km E-W and in some areas extends within 2m of the surface. Below the Laterite Zone in the residual regolith is the Oxide Zone extending from 20 to 70m vertical depth with a similar lateral extent to the Laterite Zone. Oxide mineralisation consists of numerous primary moderate to steep 60° east dipping gold bearing structures preserved in the clay rich residual profile and sub- horizontal supergene gold developed in the lower part of the profile. Host rocks for the Oxide Zone are a sequence of moderate to steep east dipping Archaean mafic rocks, including basalt and dolerite sills, and ultramafic flow sequence, intruded by late stage high level diorite and quartz-diorite sills and dykes.
The approximate dimensions of the deposit are 5,000m along strike (N-S), 700m across (E-W) for both laterite and oxide/fresh. The laterite mineralisation extends 25m maximum from surface, and the oxide/fresh mineralisation has been drilled up to 430m below surface.
Gloster.
Gold mineralisation at Gloster is within a NW-SE trending, NE dipping shear zone and associated with flat to moderately NE dipping quartz veins hosted in intermediate intrusives. A 5m transported cover sequence conceals the gold mineralisation and weathering extends up to 100m depth. Intensive gold leaching has occurred in the uppermost 15m of the weathering profile.
The approximate dimensions of the deposit are 1,200m along strike (NNW-SSE), 500m across (ENE- WSW), and 250m below surface.
Summary:
The mining method assumed in the Ore Reserve study is the same as that currently employed at the Moolart Well Gold Mine and the Gloster Gold Mine, which utilises drill and blast, excavator and truck open pit mining. The existing pit has been designed to be developed in a series of progressive cutbacks.
Processing
- Crush & Screen plant
- Gravity separation
- Carbon in leach (CIL)
- Cyanide (reagent)
Source:
Summary:
Duketon North Operations (“DNO”) comprises the Moolart Well, Gloster, Dogbolter, Petra and Anchor pits with all ore processed through the Moolart Well processing plant.
The plant design is based on a nominal 3Mtpa throughput rate utilising single stage crushing circuit and single ball mill followed by gravity and carbon in leach circuits.
Recoveries & Grades:
Commodity | Parameter | 2020 | 2019 | 2018 | 2017 | 2016 | 2015 |
Gold
|
Recovery Rate, %
| ......  | ......  | 94 | 94 | 91 | 92 |
Gold
|
Head Grade, g/t
| ......  | ......  | 1.09 | 1.14 | 0.9 | 1.14 |
Production:
Commodity | Units | 2020 | 2019 | 2018 | 2017 | 2016 | 2015 |
Gold
|
koz
| ......  | ......  | 107 | 101 | 76 | 99 |
All production numbers are expressed as metal in doré.
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Operational Metrics:
Metrics | 2020 | 2019 | 2018 | 2017 | 2016 | 2015 |
Ore tonnes mined
| ......  | 3.16 Mt | 3.15 Mt | 3.37 Mt | 2.98 Mt | 2.91 Mt |
Waste
| ......  | 6.82 Mbcm | 5,074,235 bcm | 7,768,536 bcm | 5,768,217 bcm | 4,371,317 bcm |
Tonnes milled
| ......  | 2.98 Mt | 3.26 Mt | 2.95 Mt | 2.92 Mt | 2.91 Mt |
Stripping / waste ratio
| ......  | 4.4 | 2.9 | 4.5 | 3.9 | 3.2 |
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Reserves at December 31, 2020:
Resources are reported at cut-off grade of 0.4 g/t Au.
Reserves are reported at cut-off grades not less than 0.3 g/t Au, that vary according to oxidation and lithology domains.
Category | Tonnage | Commodity | Grade | Contained Metal |
Proven
|
3 Mt
|
Gold
|
0.4 g/t
|
40 koz
|
Probable
|
18 Mt
|
Gold
|
0.8 g/t
|
430 koz
|
Proven & Probable
|
21 Mt
|
Gold
|
0.7 g/t
|
470 koz
|
Measured
|
8 Mt
|
Gold
|
0.8 g/t
|
190 koz
|
Indicated
|
33 Mt
|
Gold
|
0.7 g/t
|
800 koz
|
Inferred
|
14 Mt
|
Gold
|
0.7 g/t
|
340 koz
|
Total Resource
|
55 Mt
|
Gold
|
0.8 g/t
|
1,340 koz
|
Aerial view:
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