Overview
Stage | Production |
Mine Type | Underground |
Commodities |
|
Mining Method |
- Conventional narrow-reef mining
- Longwall
- Breast stoping with strike pillars
- Breast mining
|
Production Start | ... |
Mine Life | 2038 |
Doornkop is an underground gold mine, a deep-level, single-shaft operation. The ore mined at Doornkop is processed at the mine’s carbon-in-pulp (“CIP”) plant, which is located adjacent to the shaft.
Doornkop expansion Exploration drilling is set to continue in the coming 2024 financial year. The focus will be on targeting areas with limited geological information and those that are potentially high-grade in order to increase the geological confidence and payable ounces.
Steady-state operations with development of 207/212 level continuing. Doornkop 207/212 development project is set to be completed in 2028. |
Source:
p. 70,71
Doornkop is wholly-owned and operated by Harmony. The current mining right is held by Randfontein Estates Limited (REL), a wholly owned subsidiary of Harmony.
Contractors
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Summary:
Doornkop is situated on the northwestern margin of the Witwatersrand Basin of South Africa, one of the most prominent gold provinces in the world. While there are several gold-bearing conglomerate reefs present within the mining right area, only the Kimberley Reef and South Reef are considered to have prospects for economic extraction at this stage.
In the West Rand Goldfield, the Kimberley Reefs include a number of different gold-bearing conglomerate horizons. At Doornkop, it is the Kimberley K9 Reef horizon which comprises the Mineral Resources along with the South Reef. The K9 Reef rests on an unconformity and is a multi-pulse conglomerate which is divided into four cycles, each consisting of an upper conglomerate and a lower quartzite.
The South Reef comprises a basal conglomerate unit and a cycle of trough cross-bedded sediments. The South Reef is dominated by silicate phases such as quartz, carbon (seam and specks), as well as sulphide phases such as pyrite, pyrrhotite and chalcopyrite. While the upper cycles may carry some gold values, up to 95% of the gold present is located in the lower cycle.
Both the Kimberley Reef and the South Reef have been subjected to faulting and are intruded by a series of dykes and sills of various ages that cut across the reefs. The gold mineralisation is interpreted to have succeeded a period of deep burial, fracturing, and alteration. The gold and other elements are believed to have precipitated through ........
Mining Methods
- Conventional narrow-reef mining
- Longwall
- Breast stoping with strike pillars
- Breast mining
Summary:
Doornkop is a single-shaft operation exploiting the South Reef to some 2 000m below surface. The narrow South Reef is exploited by means of conventional stoping. Mining of the Kimberley Reef was suspended during FY14 to focus on the build-up production from the South Reef and to prevent losses as a result of the lower gold price. Mining of the Kimberley Reef may resume should economic circumstances improve sufficiently.
The mining method used is longwall mining with stability pillars on major geological structures. Geotechnical dip pillars have been introduced between raiseline to minimise seismicity. The flat dip, which results in the development of long cross-cuts, presents challenges in terms of ore handling, especially for the bottom part of the raises, ventilation and in the long lead times between the start of cross-cut development to completion of stoping per raise line.
The operation is focused on narrow-reef conventional mining of the gold-bearing conglomerate South Reef.
The mining method used at Doornkop is conventional breast mining, in a sequential grid, also known as sequential grid mining (“SGM”).
Doornkop does not use backfill for the support of stopes. The SGM method makes use of dip pillars and reduced mining spans with pre-developed tunnels, aimed at controlling geotechnical stress.
The mining sequence at Doornkop is typically a V-shaped configuration, colloquially referred to as the “inverted Christmas ........
Source:
Flow Sheet:
Summary:
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Source:
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Reserves at June 30, 2023:
Mineral Reserves are reported using a cut-off grade of 739cmg/t determined using a gold price of US$1.582/oz.
The Mineral Resources are reported using a cut-off value of 650 cmg/t determined at a 90% profit guidance, and a gold price of US$1,764/oz.
Mineral Resources are reported inclusive of Mineral Reserves.
Category | Tonnage | Commodity | Grade | Contained Metal |
Proven
|
5.2 Mt
|
Gold
|
4.35 g/t
|
728 koz
|
Probable
|
8.2 Mt
|
Gold
|
4.44 g/t
|
1,172 koz
|
Proven & Probable
|
13.4 Mt
|
Gold
|
4.41 g/t
|
1,901 koz
|
Measured
|
21.5 Mt
|
Gold
|
4.08 g/t
|
2,822 koz
|
Indicated
|
17 Mt
|
Gold
|
4.42 g/t
|
2,410 koz
|
Inferred
|
13.3 Mt
|
Gold
|
4.53 g/t
|
1,931 koz
|
Total Resource
|
51.7 Mt
|
Gold
|
4.31 g/t
|
7,163 koz
|
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