Overview
| Stage | Production |
| Mine Type | Open Pit |
| Commodities |
|
| Mining Method |
|
| Processing |
- Gravity separation
- Counter current decantation (CCD)
- Concentrate leach
- Carbon in leach (CIL)
- Merrill–Crowe
- Cyanide (reagent)
|
| Production Start | 2010 |
| Mine Life | 6 years (as of Jan 1, 2021) |
Hidden Valley extension project – a feasibility study is being conducted. This project in Papua New Guinea will be self-funded and will extend the life of mine to 2027. Harmony Gold expects the project to deliver approximately 160 000oz to 200 000oz of gold per annum and 2.1Moz to 3.1Moz of silver per annum at a life of mine all-in sustaining cost of $1 017/oz. |
Source:
p. 40
Morobe Consolidated Goldfields Limited, being a wholly owned subsidiary of Harmony registered in Papua New Guinea, is the 100% owner and operator of the Hidden Valley Mine.
Contractors
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Deposit Type
- Vein / narrow vein
- Breccia pipe / Stockwork
Summary:
The deposit is a structurally controlled vein-stockwork gold-silver deposit located in the Morobe Granodiorite of the Wau Graben. Goldsilver mineralisation is contained in carbonate-adularia- quartz-sulphide vein-stockworks and in a few instances in hydrothermal breccias. Discrete zones of intense stockwork fracture and mineralised veining comprise individual lodes. At the Hidden Valley deposit, gold and silver are related to steeply to moderately dipping sheeted vein swarms associated with an underlying shallow thrust.
Summary:
The Hidden Valley Mine is an operating open-pit gold and silver mine. An extension to the mine life has been approved taking the end of mine out to 2027 with further opportunities for extension.
Mining operations occur in two open pits 6km apart, Hidden ValleyKaveroi and Hamata of which Hidden Valley-Kaveroi is the largest. Both mines employ conventional open pit mining techniques with backhoe excavators and rigid dump trucks as the primary load and haul equipment. Front-end loaders are used for crusher feed and stockpile reclaim. A number of articulated smaller dump trucks are used for construction and to a lesser extent mining in Hamata.
Mining bench configuration generally consists of 18m inter-berm heights, blasted in 2m x 9m benches with 3m mining flitches.
Waste is disposed of in engineered valley fill waste dumps, with toes keyed in and buttressed using competent non-acid forming rock. Waste from the Hidden Valley-Kaveroi open pit is currently placed in the valley fill Western Sector and Niekywe waste dumps.These dumps provide enough capacity for life of mine.
Source:
- subscription is required.
Processing
- Gravity separation
- Counter current decantation (CCD)
- Concentrate leach
- Carbon in leach (CIL)
- Merrill–Crowe
- Cyanide (reagent)
Source:
Summary:
The Hidden Valley process plant was designed to treat nominally 4.0 Mtpa of gold/silver bearing ore. The process uses a two stage crushing circuit followed by a SAG mill, gravity, CCD/Merrill Crowe circuit for silver and a carbon-in-leach circuit for the gold. A silver/gold ore bar is produced and flown off site for refining and sale.
Tailings are disposed of in a terrestrial tailings storage facility located to the south-west of the process plant. Dam-wall construction of the tailings storage facility is ongoing and largely constitutes placement of suitable oxide and fresh competent material sourced from mining in the Hamata pit and nearby quarry. The processing inventory in this ore reserve estimate is constrained by the remaining storage capacity. The Hidden Valley Extension study contemplates construction of an additional facility, TSF2.
Recoveries & Grades:
| Commodity | Parameter | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 | 2015 |
|
Gold
|
Recovery Rate, %
| ...... | ...... | | | | 86.5 | 86.6 |
|
Gold
|
Head Grade, g/t
| ...... | ...... | ...... | 1.36 | 1.07 | 1.51 | 1.84 |
Reserves at June 30, 2021:
Hidden Valley Gold – Mineral Resource 2021 cut-off 0.65 g/t.
Hidden Valley Silver – Mineral Resource 2021 cut-off 0.85 g/t.
| Category | Tonnage | Commodity | Grade | Contained Metal |
|
Proven
|
3.4 Mt
|
Gold
|
0.95 g/t
|
103 koz
|
|
Proven
|
3.4 Mt
|
Silver
|
17.31 g/t
|
1,886 koz
|
|
Probable
|
20.1 Mt
|
Gold
|
1.59 g/t
|
1,030 koz
|
|
Probable
|
19.9 Mt
|
Silver
|
27.18 g/t
|
17,363 koz
|
|
Proven & Probable
|
23.5 Mt
|
Gold
|
1.5 g/t
|
1,134 koz
|
|
Proven & Probable
|
23.3 Mt
|
Silver
|
25.75 g/t
|
19,249 koz
|
|
Measured
|
3.4 Mt
|
Gold
|
0.95 g/t
|
103 koz
|
|
Measured
|
3.4 Mt
|
Silver
|
17.31 g/t
|
1,886 koz
|
|
Indicated
|
55.9 Mt
|
Gold
|
1.44 g/t
|
2,585 koz
|
|
Indicated
|
54.1 Mt
|
Silver
|
22.26 g/t
|
38,682 koz
|
|
Inferred
|
1.6 Mt
|
Gold
|
1.11 g/t
|
57 koz
|
|
Inferred
|
1.4 Mt
|
Silver
|
20.63 g/t
|
941 koz
|
|
Total Resource
|
60.9 Mt
|
Gold
|
1.4 g/t
|
2,746 koz
|
|
Total Resource
|
58.9 Mt
|
Silver
|
21.93 g/t
|
41,508 koz
|
Commodity Production Costs:
| | Commodity | Units | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 |
|
Cash costs
|
Gold
|
USD
|
|
|
|
824 / oz
|
1,252 / oz
|
1,320 / oz
|
|
Cash costs
|
Gold
|
USD
|
...... †
|
...... †
|
...... †
|
669 / oz†
|
1,068 / oz†
|
1,028 / oz†
|
|
All-in sustaining costs (sold)
|
Gold
|
USD
|
|
|
|
1,261 / oz
|
1,417 / oz
|
1,564 / oz
|
|
All-in sustaining costs (sold)
|
Gold
|
USD
|
...... †
|
...... †
|
...... †
|
1,094 / oz†
|
1,241 / oz†
|
1,282 / oz†
|
† Net of By-Product.
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Operating Costs:
| | Units | 2017 | 2016 |
|
Total operating costs ($/t milled)
|
USD
| 33 | 39 |
Financials:
| | Units | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 |
|
Capital expenditures (planned)
|
M ZAR
| ...... | | | | |
|
|
|
Capital expenditures
|
M
| | ...... | ...... | ...... | 122 USD |
98 USD
|
10 USD
|
|
Revenue
|
M
| | ...... | ...... | ...... | 32 USD |
110 USD
|
216 USD
|
|
Gross profit
|
M
| | ...... | ...... | ...... | 14 USD |
14 USD
|
|
|
EBIT
|
M
| | | | | |
|
-18 USD
|
|
EBITDA
|
M
| | | | | |
|
6 USD
|
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