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 | 2030 |
St Ives is a multiple mining operation consist of Invincible underground complex, Hamlet underground and Neptune open pit.
In 2022, a notable highlight was the extension of mine life at Hamlet from 2023 to 2026 and the continued expansion of the Invincible Complex. The mine continues to transition to a predominantly underground operation with the majority of production from the Invincible Complex and the Hamlet North underground mines.
At St Ives, a feasibility study continues to evaluate alternative power sources for when the current power supply agreement ends in 2024. |
Source:
p. 177,308
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
- Subscription is required.
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.
• The Black Flags Mudstone (BFM): Is the main unit to the host min ........
Mining Methods
- Truck & Shovel / Loader
- Longhole open stoping
- Cut & Fill
- Room-and-pillar
- Cemented paste backfill
- Unconsolidated rockfill
Summary:
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 pit
Open pit mining at St Ives is by conventional drill and blast / truck and shovel extraction. Grade control is generally by inclined RC drilling on approximately 5 m x 10 m centres in plan projection. Production drilling ranges from 3.0 m x 3.5 m up to 5.0 m x 6.0 m patterns. Pre-split blasting in hard rock is utilised on 10 m to 20 m benches in fresh rock where required.
Open pit projects may include 10 m to 50 m of unconsolidated sedimentary overburden which require hard rock for sheeting to enable equipment traffic capability during mining and/or dewatering of the sedimentary overburden prior to mining.
Load and haul are completed by 90 t to 150 t dump trucks with 120 t to 300 t excavators in backhoe configuration mining benches varying from 5 to 10 m. The benches are generally excavated in p ........
Source:
Source:
- subscription is required.
Flow Sheet:
Summary:
- subscription is required.
Pipelines and Water Supply
Source:
- subscription is required.
Production:
Commodity | Units | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 |
Gold
|
koz
| ...... ^ | ...... | ...... | ...... | ...... | 367 | 364 |
All production numbers are expressed as metal in doré.
^ Guidance / Forecast.
- Subscription is required.
Operational Metrics:
Metrics | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 |
Plant annual capacity
| ...... | ...... | ...... | 4.7 Mt | 4.7 Mt | 4.7 Mt |
Waste
| ...... | ...... | ...... | 10,087 kt | 17,737 kt | 38,547 kt |
Ore tonnes mined
| ...... | ...... | ...... | 5,080 kt | 4,307 kt | 4,466 kt |
Total tonnes mined
| ...... | ...... | ...... | 15,167 kt | 22,044 kt | 43,012 kt |
Tonnes processed
| ...... | ...... | ...... | 4,466 kt | 4,250 kt | 4,198 kt |
- Subscription is required.
Reserves at December 31, 2022:
Mineral Reserves: Cut-off for oxide ore 0.35 – 0.45 g/t; Cut-off for fresh ore 0.30 – 3.6 g/t; Cut-off for mill feed underground 2.4 – 3.6 g/t; Cut-off for mill feed open pit 0.30 – 0.45 g/t.
Mineral Resources: Cut-off for oxide ore 0.79 – 1.17 g/t; Cut-off for fresh ore 0.75 – 4.4 g/t; Cut-off for mill feed 0.75 – 4.4 g/t; Cut-off for open pit 0.75 – 1.17 g/t; Cut-off for underground 1.9 – 4.4 g/t.
Category | OreType | Tonnage | Commodity | Grade | Contained Metal |
Proven & Probable
|
Stockpiles
|
3,029 kt
|
Gold
|
1.3 g/t
|
126 koz
|
Proven & Probable
|
In-Situ (OP)
|
3,193 kt
|
Gold
|
2.4 g/t
|
242 koz
|
Proven & Probable
|
In-Situ (UG)
|
18,403 kt
|
Gold
|
4 g/t
|
2,345 koz
|
Proven & Probable
|
Total
|
24,626 kt
|
Gold
|
3.4 g/t
|
2,713 koz
|
Measured & Indicated
|
In-Situ (OP)
|
6,073 kt
|
Gold
|
2.4 g/t
|
471 koz
|
Measured & Indicated
|
In-Situ (UG)
|
4,238 kt
|
Gold
|
3.6 g/t
|
493 koz
|
Measured & Indicated
|
Total
|
10,312 kt
|
Gold
|
2.9 g/t
|
964 koz
|
Inferred
|
In-Situ (OP)
|
1,753 kt
|
Gold
|
2.7 g/t
|
155 koz
|
Inferred
|
In-Situ (UG)
|
9,550 kt
|
Gold
|
4 g/t
|
1,277 koz
|
Inferred
|
Total
|
11,303 kt
|
Gold
|
3.9 g/t
|
1,432 koz
|
HME Type | Model | Size | Quantity | Ref. Date | Source |
Dozer (crawler)
|
.......................
|
|
.......................
|
Dec 31, 2021
|
p.98
|
Dozer (rubber tire)
|
.......................
|
|
.......................
|
Dec 31, 2021
|
p.98
|
Drill
|
.......................
|
|
.......................
|
Dec 31, 2021
|
p.98
|
Drill (blasthole)
|
.......................
|
|
.......................
|
Dec 31, 2021
|
p.98
|
Drill (long hole)
|
|
|
.......................
|
Dec 31, 2021
|
p.98
|
Excavator
|
.......................
|
|
.......................
|
Dec 31, 2021
|
p.98
|
Excavator
|
.......................
|
|
.......................
|
Dec 31, 2021
|
p.98
|
Grader
|
.......................
|
|
.......................
|
Dec 31, 2021
|
p.98
|
Jumbo
|
|
|
.......................
|
Dec 31, 2021
|
p.98
|
Loader
|
.......................
|
18 t
|
.......................
|
Sep 21, 2021
|
|
Load-Haul-Dump (LHD)
|
|
|
.......................
|
Dec 31, 2021
|
p.98
|
Truck (dump)
|
.......................
|
150 t
|
.......................
|
Dec 31, 2021
|
p.98
|
Truck (dump)
|
.......................
|
|
.......................
|
Dec 31, 2021
|
p.98
|
Truck (underground)
|
|
|
.......................
|
Dec 31, 2021
|
p.98
|
Truck (underground)
|
.......................
|
50 t
|
.......................
|
Sep 21, 2021
|
|
- Subscription is required.
Corporate Filings & Presentations:
- Subscription is required.
- Subscription is required.