Hidden Valley is a single open-pit gold and silver mining operation located at 1 700m to 2 800m above sea level in steep, mountainous and forested terrain with high annual rainfall. The major gold and silver deposits are in the Morobe Granodiorite of the Wau Graben.
Crushed ore is transported from the pit via a 5.5km overland pipe conveyor to the Hidden Valley processing plant where it is treated using a two-stage milling and crushing circuit followed by a counter current decantation/Merril Crowe circuit for silver and a carbon-in-leach circuit for gold.
Key facts
Location:
Papua New Guinea
in Morobe Province, some 210km north-west of the capital Port Moresby
Nature of mining
Open pit
conventional open-pit techniques using mining bench configuration
Mining Parameters
blasting done in 2m x 9m benches with 3m mining flitches; an inter-berm height of 18m applied
Life-of-mine
5 years
Harmony South East Asia
Tel: +61 7 3320 3700
Fax: +61 7 3320 3740
Address
Level 2, 189 Coronation Drive
Milton, Queensland 4064
Australia
PO Box 1562
Milton, Queensland 4064 Australia
Current focus
- Ensuring safe, environmentally responsible, margin-focused production against plan
- Progressing project studies for life-of-mine extension
For more information, refer to:
Performance FY25
Production
164 193oz
(5 107kg)
Grade
1.35g/t
(0.039oz/t)
All-in sustaining cost
R868 228/kg
(US$1 486/oz)
Capital expenditure
R1 620m
(US$89m)
Reserves and resources
Gold and gold equivalent Mineral Reserves
1.0Moz
Gold and gold equivalent Resources (inclusive)
2.5Moz
Guidance FY26
production
179 400oz –
190 800oz
capital expenditure
~R3 437m
ESG statistics
Lost-time injury frequency rate
0.00
per million hours worked
Workforce
2 366
1 416 permanent employees and 950 contractors
WATER INTENSITY
0.54Mℓ
per tonne treated
Energy intensity
0.04MWh
per tonne treated
GHG intensity
0.05t CO2e
per tonne treated
TOTAL COMMUNITY SPEND*
R129m
(US$7m)
* For Papua New Guinea in total
Linking rural infrastructure with agricultural initiatives for lasting impact
As Hidden Valley mine considered its contribution to host communities and alignment with district development plans, it became clear that safe and fit-for-purpose rural roads are essential for supporting agricultural entrepreneurship.
