Overview
Stage | Production |
Mine Type | Underground |
Commodities |
|
Mining Method |
- Sub-level open stoping (SLOS)
- Cemented backfill
|
Production Start | ...  |
Mine Life | 2038 |
Construction of the Wira Shaft is underway, and this brownfield expansion will extend Prominent Hill’s life of mine to 2038. As part of project optimisation works done in 2022, this electric hoisting shaft’s capacity was increased from 6Mtpa to 6.5Mtpa. The increased capacity will provide us with optionality to increase Prominent Hill’s annual production rates.
The shaft headframe is planned for installation in the first half of 2023. |
Latest News | BHP: Completion of OZ Minerals acquisition May 2, 2023 |
Source:
OZ Minerals Ltd. indirectly owns 100% interest in the Prominent Hill operation through its wholly owned subsidiary OZ Minerals Prominent Hill Operations Pty Ltd.
On May 2, 2023, BHP announced the completion of the OZ Minerals acquisition and implementation of the scheme of arrangement for BHP Lonsdale Investments Pty Limited, a wholly owned subsidiary of BHP Group Limited, to acquire 100% of the shares in OZ Minerals Limited (OZL) (the Scheme). BHP Group Limited is now the ultimate parent company of OZL.
Contractors
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Deposit Type
- Breccia pipe / Stockwork
- IOCG
Summary:
The Prominent Hill iron oxide copper gold (IOCG) deposit is located in the northeastern portion of the Archaean to Mesoproterozoic Gawler Craton, South Australia. Copper-gold-silver mineralisation at Prominent Hill is mostly hosted within hematitematrix breccia containing fragments of sandstone, siltstone, dolostone, and mafic to intermediate volcanic rocks. Copper mineralisation occurs as disseminations of chalcocite, bornite and chalcopyrite in the matrix of the breccia.
Mineralisation generally has a tabular geometry. Most but not all copper mineralisation is hosted in hematite breccia. Gold mineralisation is commonly coincident with copper mineralisation, but some zones of gold-only mineralisation do exist. Copper grades generally show better spatial continuity within hematite breccia than within other rock types. Barren dykes cross cut the mineralisation. Barren covering sediments overlie the mineralised basement rocks.
The current maximum extent of the reported Mineral Resource is 2,600m (east-west) by 1,400m (vertical). Multiple lenses exist within a mineralised zone having a plan width (across strike) of approximately 300-400m. Only a subset of this mineralised zone has sufficient continuity of grade to have been reported as a Mineral Resource. The upper and lower limits of the reported Mineral Resource are 100m and 1,462m respectively below the pre-mining topographic surface.
Mining Methods
- Sub-level open stoping (SLOS)
- Cemented backfill
Summary:
The Prominent Hill Underground Mineral Resource is being mined successfully using sub-level open stoping (SLOS) with cemented fill. Access to the ore body and ore haulage is carried out via decline (ramp) system. Operations are performed by mining contractor.
On August 18, 2021, The OZ Minerals Board approved construction of a hoisting shaft at the Prominent Hill copper-gold mine in South Australia, paving the way for a mine life extension and throughput expansion.
Sinking of the shaft is expected to commence in the March quarter of 2022. Mining and installation of underground and surface infrastructure is scheduled for completion along with commissioning of the Wira shaft at the end of 2024, with nameplate capacity expected in H1 2025.
The shaft design comprises a 1,329 metre deep, concrete lined shaft with a diameter of 7.5 metres.
The company plans to reduce its underground loading fleet to eight vehicles, from nine after the shaft expansion, with its trucking fleet going from circa-14 to five, post-shaft.
Prominent Hill is an operating mine and has the majority of necessary infrastructure in place for its continued operation.
Two new primary ventilation fans were commissioned in Q2 2020. This is the third pair of primary ventilation fans installed at Prominent Hill.
A second paste fill plant was successfully commissioned in mid-2020 and is capable of providing cemented fill at a rate to suppor ........

Flow Sheet:
Crushing and Grinding
Ore is hauled from the mine directly to the primary crusher or stockpiled on the ROM pad until such time as it can be processed. Mineralised waste is stockpiled separately to allow for future reprocessing should this be determined to be economically viable.
The ore is taken from the mine or reclaimed from the ROM stockpiles and tipped into the primary crusher, located adjacent to the ROM pad, where it is crushed to a size of less than 125 mm. The nominal crusher throughput is up to 3,600 tonnes per hour, approximately three times the throughput of the grinding circuit. The ore is then conveyed to the crushed ore stockpile. It is reclaimed from the bottom of the stockpile and conveyed to the semi-autogenous grinding (SAG) mill which operates in a closed circuit with a vibrating screen and pebble recycle circuit. Grinding balls at 125 mm are added including water inside the SAG mill to reduce the ore to micron size contained in a slurry form. Material that doesn’t pass through the 5 x 20 mm screen is recycled back to the SAG mill for further grinding. The slurry containing the fine material that passes through the 5 x 20 mm screen is combined along with the ball mill discharge to slurry feed the primary hydrocylone pack for classification. The primary hydrocyclone separates the material by size, where the overflow fines report to flotation, and the underflow coarse returns to the ball mill where 60 mm balls are added for further grinding. The SAG and ball mill operates in closed circuit with the primary hydrocyclone pack. Dust generation occurs during the dry stages of crushing and when transporting ore to the coarse ore stockpile (COS). Water sprays are used in the crusher pocket and at the discharge of the first conveyor (CV1) to manage the dust. The rest of the size reduction process (grinding) is a wet process where no dust is generated.
The SAG/ball milling circuit enables 80% of the material is sized to less than 125 µm, and becomes suitable for further processing.
Flow Sheet:
Summary:

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Reserves at June 30, 2022:
The A$48/t Net Smelter Return (NSR) cut-off for the Prominent Hill Underground Mineral Resource
Prominent Hill Underground Reserve cut-off value: Ankata orebody were designed to a $65 NSR shell, the Malu orebody were designed to a $75 NSR shell and Kalaya and Malu Deeps West to a $70 NSR shell.
Category | Tonnage | Commodity | Grade | Contained Metal |
Proven
|
29 Mt
|
Copper
|
1.2 %
|
340 kt
|
Proven
|
29 Mt
|
Gold
|
0.6 g/t
|
520 koz
|
Proven
|
29 Mt
|
Silver
|
2.9 g/t
|
2.7 M oz
|
Proven
|
29 Mt
|
Copper Equivalent
|
1.5 %
|
|
Probable
|
30 Mt
|
Copper
|
0.9 %
|
250 kt
|
Probable
|
30 Mt
|
Gold
|
0.7 g/t
|
710 koz
|
Probable
|
30 Mt
|
Silver
|
2.4 g/t
|
2.3 M oz
|
Probable
|
30 Mt
|
Copper Equivalent
|
1.3 %
|
|
Proven & Probable
|
59 Mt
|
Copper
|
1 %
|
590 kt
|
Proven & Probable
|
59 Mt
|
Gold
|
0.7 g/t
|
1,230 koz
|
Proven & Probable
|
59 Mt
|
Silver
|
2.6 g/t
|
5 M oz
|
Proven & Probable
|
59 Mt
|
Copper Equivalent
|
1.4 %
|
|
Measured
|
49 Mt
|
Copper
|
1.2 %
|
580 kt
|
Measured
|
49 Mt
|
Gold
|
0.6 g/t
|
930 koz
|
Measured
|
49 Mt
|
Silver
|
3 g/t
|
4.7 M oz
|
Measured
|
49 Mt
|
Copper Equivalent
|
1.6 %
|
|
Indicated
|
51 Mt
|
Copper
|
0.9 %
|
440 kt
|
Indicated
|
51 Mt
|
Gold
|
0.9 g/t
|
1,500 koz
|
Indicated
|
51 Mt
|
Silver
|
2.5 g/t
|
4.1 M oz
|
Indicated
|
51 Mt
|
Copper Equivalent
|
1.4 %
|
|
Inferred
|
66 Mt
|
Copper
|
0.8 %
|
560 kt
|
Inferred
|
66 Mt
|
Gold
|
0.9 g/t
|
1,900 koz
|
Inferred
|
66 Mt
|
Silver
|
2.3 g/t
|
4.8 M oz
|
Inferred
|
66 Mt
|
Copper Equivalent
|
1.4 %
|
|
Total Resource
|
170 Mt
|
Copper
|
0.9 %
|
1,600 kt
|
Total Resource
|
170 Mt
|
Gold
|
0.8 g/t
|
4,300 koz
|
Total Resource
|
170 Mt
|
Silver
|
2.5 g/t
|
14 M oz
|
Total Resource
|
170 Mt
|
Copper Equivalent
|
1.4 %
|
|
Operating Costs:
| Units | 2016 |
UG mining costs ($/t mined)
|
AUD
| 53 |
Source:

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