Overview
| Stage | Production |
| Mine Type | Underground |
| Commodities |
|
| Mining Method |
- Bench stoping
- Paste backfill
|
| Processing |
- Gravity separation
- Concentrate leach
- Agitated tank leaching
- Carbon in pulp (CIP)
- AARL elution
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
|
Summary:
Structurally controlled deposit within a NNW trending shear associated with the regional Zuleika Shear Zone, on the lithological contact between the Victorious Basalt and Black Flag Volcanic Sediments. Mineralisation occurs in laminated quartz veins, brecciation and alteration zones with widths ranging from 0.2-20m along strike length of 0.3-1.0km.
The Frog’s Leg deposit is located in the southern portion of the Kundana mining area, within the Achaean Norseman-Wiluna greenstone belt of the Eastern Goldfields Province. The Kundana gold deposits are structurally related to the Zuleika Shear Zone, a regional NNW-trending shear zone that juxtaposes the Ora Banda domain to the east and the Coolgardie domain to the west. The Frog’s Leg deposit is located on the sheared contact between the porphyritic “cat rock” (regionally known as the Victorious Basalt) and volcaniclastic rocks of Black Flag Beds.
Mineralisation at Frog’s Leg is hosted within a number of steeply dipping NNW-SSE structures that are vertical or dipping steeply (~80 degrees) to the west. Surface and underground drilling intersect the mineralisation at an angle to minimise bias.
Mining Methods
- Bench stoping
- Paste backfill
Summary:
At underground mine, Frog’s Leg mining methodology is top-down bench stoping with paste fill.
5m x 5.5m decline from portal in pit, then twin declines from 125 metres below surface (mbs) to access north (Mist) and south (Rocket) sections. Deepest point current 550mbs, bottom of reserve is 650mbs.
Processing Technologies
- Gravity separation
- Concentrate leach
- Agitated tank leaching
- Carbon in pulp (CIP)
- AARL elution
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
Flow Sheet:
Summary:
Three stage crushing: Primary Metso C140 Jaw crusher (220kW) -1250 x 940mm throat- feed size 800mm, product size p80-120mm. Secondary(1) and tertiary(1) crushers: Metso HP 4 (315kW) Product size 17mm. Product Screen: Joest inclined vibrating screen 2.44 x 7.6m. 4 x conveyor belts, Belt and static magnets as well as a rock breaker for the primary crusher.
Ball Mill with 4,500kW installed power, Mill size 5.5m(dia) x 8.74m(l), Polymet composite liners, Classification Weir Cavex 250mm (x11) Grind size p80 – 106 µm. Gravity & CIP
CIP leach circuit with 2 x 1,140m tanks and 6 x 750m adsorption tanks. Elution circuit – split AARL. 3 x Electrowinning tanks - Consep, 2 in parallel for leach circuit and 1 for gravity circuit
Recoveries & Grades:
| Commodity | Parameter | 2018 |
|
Gold
|
Head Grade, g/t
| 5.32 |
Production:
| Commodity | Units | 2018 |
|
Gold
|
koz
| ......  |
All production numbers are expressed as metal in ore.
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Operational Metrics:
| Metrics | 2018 | 2017 | 2016 |
|
Ore tonnes mined
| ...... | ...... | 563 kt |
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Reserves at December 31, 2018:
| Category | Tonnage | Commodity | Grade | Contained Metal |
|
Proven
|
0.2 Mt
|
Gold
|
5.26 g/t
|
34 koz
|
|
Probable
|
0.54 Mt
|
Gold
|
4.58 g/t
|
80 koz
|
|
Proven & Probable
|
0.74 Mt
|
Gold
|
4.77 g/t
|
113 koz
|
|
Measured
|
0.32 Mt
|
Gold
|
8.4 g/t
|
86 koz
|
|
Indicated
|
2.39 Mt
|
Gold
|
3.61 g/t
|
278 koz
|
|
Inferred
|
2.32 Mt
|
Gold
|
3.31 g/t
|
247 koz
|
|
Total Resource
|
5.04 Mt
|
Gold
|
3.78 g/t
|
611 koz
|
Aerial view:
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