Overview
Stage | Production |
Mine Type | Open Pit & Underground |
Commodities |
|
Mining Method |
- Truck & Shovel / Loader
- Longhole open stoping
- Cut & Fill
- Room-and-pillar
- Cemented paste backfill
- Unconsolidated rockfill
|
Production Start | ... |
Mine Life | 2031 |
St Ives operations consist of the Invincible and Hamlet North underground mines as well as open pit mining in the Neptune – Revenge area.
The LOM mining mix has been transitioning from open-pit to underground operations over the last few years but discovering new, sizeable open-pit opportunities will continue to be prioritised to rebalance the overall mix.
Open-pit production continued at Neptune with mining in stage seven, which is now completed.
During 2024, drilling at Hamlet will target historical remnants and near-mine exploration opportunities to support LOM extension.
An FS for the IFWS open-pit project was completed in 2023. The study pipeline for 2024 will focus on the Invincible Complex with bulk mining, haulage and decarbonisation studies planned. |
Source:
p. 294,479
Gold Fields Limited indirectly owns 100% interest in the St Ives mine through it's wholly owned subsidiary St Ives Gold Mining Company (Pty) Ltd.
Contractors
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Deposit Type
- Vein / narrow vein
- Mesothermal
- Paleoplacer
Summary:
Mineralisation
There are four main styles of gold mineralisation at St Ives. Individual deposits may contain more than one style depending on the local structural and lithological conditions:
• Lode mineralisation: typically consists of a 0.5 cm to 50 cm wide cataclasite core surrounded by 0.1 cm to 3.0 m of foliated cataclasite.
• Quartz vein stockworks: irregular bodies of closely spaced and regularly oriented quartz veins.
• Composite style: variably developed quartz vein stockwork mineralisation localised in and around lode shear zones.
• Supergene: broad zones of flat-lying gold mineralisation hosted in deeply weathered Archean and overlying Tertiary rocks.
The current major production centres at St Ives are the Invincible deposits, the Neptune paleochannel and underlying lodes and the Hamlet deposit.
Invincible
Invincible is situated on Lake Lefroy, approximately 8 km northwest of the Lefroy process plant. The Invincible camp is dominated by a 2 km long open pit mined between 2014 and 2019, with mineralisation extending a further 1.9 km to the south of the pit (Invincible South) and >800 m depth (Invincible Deeps).
There are three major lithofacies identified at the Invincible Camp:
• The Black Flags Andesite (BFA): This unit forms the footwall sequence at Invincible and consists of volcanic quartz-rich sandstone with lenses of polymictic sub-rounded to sub angular pebble to cobble conglomerate.
Mining Methods
- Truck & Shovel / Loader
- Longhole open stoping
- Cut & Fill
- Room-and-pillar
- Cemented paste backfill
- Unconsolidated rockfill
Summary:
St Ives operated two underground mines and three open pits in 2023.
The underground mines are accessed via a decline. Mining contractors (Invincible and Hamlet) took over the mining activities in 2023. Paste/rock fill is a mix of owner-operator and contractor. Current underground mines are configured to mitigate geotechnical seismic risk through mine design, scheduling and defined ground support regimes as mining transitions to deeper mining at both Hamlet and Invincible.
Open pits are mined using conventional drill and blast with truck and shovel. Surface mining operations are conducted using an owner-operator mining fleet.
Ore from both open pit and underground operations is transported with road trains from individual mining operations to the central St Ives processing ROM pad.
The gold mineralisation at St Ives is mined via both open pit and underground methods to depths generally not exceeding 1,000 m below surface. Some projects involve mining deposits on or under the Lake Lefroy salt lake so that extraction requires construction of bunds and other earthworks to provide access, stockpile areas and to prevent surface water incursion.
St Ives has four underground mine areas and seven open pits contributing to the Mineral Reserve. There are seven underground mines and 16 open pits contributing to the Mineral Resource. Current ore stockpiles contribute 4.6% of the Mineral Reserve at the reporting date.
Open p ........
Source:
Source:
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Flow Sheet:
Summary:
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Pipelines and Water Supply
Source:
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Reserves at December 31, 2023:
Mineral Reserves: Cut-off for oxide ore 0.35 – 0.45 g/t; Cut-off for fresh ore 0.35 – 3.6 g/t; Cut-off for mill feed underground 2.3 – 3.6 g/t; Cut-off for mill feed open pit 0.35 – 0.45 g/t.
Mineral Resources: Cut-off for oxide ore 0.77 – 1.05 g/t; Cut-off for fresh ore 0.63 – 4.3 g/t; Cut-off for mill feed 0.63 – 4.3 g/t; Cut-off for open pit 0.63 – 1.05 g/t; Cut-off for underground 2.3 – 4.3 g/t.
Category | OreType | Tonnage | Commodity | Grade | Contained Metal |
Proven & Probable
|
Stockpiles
|
2,747 kt
|
Gold
|
1.1 g/t
|
97 koz
|
Proven & Probable
|
In-Situ (OP)
|
4,232 kt
|
Gold
|
2.2 g/t
|
304 koz
|
Proven & Probable
|
In-Situ (UG)
|
17,126 kt
|
Gold
|
4 g/t
|
2,209 koz
|
Proven & Probable
|
Total
|
24,104 kt
|
Gold
|
3.4 g/t
|
2,610 koz
|
Measured & Indicated
|
In-Situ (OP)
|
3,653 kt
|
Gold
|
2.7 g/t
|
318 koz
|
Measured & Indicated
|
In-Situ (UG)
|
5,103 kt
|
Gold
|
4.1 g/t
|
676 koz
|
Measured & Indicated
|
Total
|
8,755 kt
|
Gold
|
3.5 g/t
|
994 koz
|
Inferred
|
In-Situ (OP)
|
1,064 kt
|
Gold
|
3 g/t
|
102 koz
|
Inferred
|
In-Situ (UG)
|
7,304 kt
|
Gold
|
4 g/t
|
936 koz
|
Inferred
|
Total
|
8,368 kt
|
Gold
|
3.9 g/t
|
1,038 koz
|
HME Type | Model | Size | Quantity | Leased or Contractor | Ref. Date | Source |
Dozer (crawler)
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.......................
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.......................
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Dec 31, 2021
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p.98
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Dozer (rubber tire)
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.......................
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.......................
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Dec 31, 2021
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p.98
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Drill
|
.......................
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.......................
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Dec 31, 2022
|
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Drill
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.......................
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.......................
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Dec 31, 2022
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Drill
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.......................
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Dec 31, 2022
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Drill
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.......................
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.......................
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Dec 31, 2022
|
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Drill
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.......................
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.......................
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Dec 31, 2021
|
p.98
|
Drill (blasthole)
|
.......................
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.......................
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Dec 31, 2021
|
p.98
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Drill (long hole)
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|
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.......................
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Dec 31, 2021
|
p.98
|
Excavator
|
.......................
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.......................
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Dec 31, 2021
|
p.98
|
Excavator
|
.......................
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.......................
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Dec 31, 2021
|
p.98
|
Explosives Charger
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.......................
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.......................
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Dec 31, 2022
|
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Grader
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.......................
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.......................
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Dec 31, 2021
|
p.98
|
Jumbo
|
|
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.......................
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Dec 31, 2021
|
p.98
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Loader - AV
|
.......................
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18 t
|
.......................
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Sep 21, 2021
|
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Load-Haul-Dump (LHD)
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.......................
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.......................
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Dec 31, 2022
|
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Load-Haul-Dump (LHD)
|
|
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.......................
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Dec 31, 2021
|
p.98
|
Truck (dump)
|
.......................
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150 t
|
.......................
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Dec 31, 2021
|
p.98
|
Truck (dump)
|
.......................
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.......................
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Dec 31, 2021
|
p.98
|
Truck (underground)
|
|
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.......................
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Dec 31, 2021
|
p.98
|
Truck (underground)
|
.......................
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.......................
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Dec 31, 2022
|
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Truck (underground) - AV
|
.......................
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50 t
|
.......................
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Sep 21, 2021
|
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AV - Autonomous
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