Overview
Stage | Construction |
Mine Type | Open Pit |
Commodities |
|
Mining Method |
|
Processing |
- Gravity separation
- Dewatering
- Carbon in leach (CIL)
- Elution
- Carbon adsorption-desorption-recovery (ADR)
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
|
Mine Life | 13 years (as of Jan 1, 2018) |
During the December 2021 Quarter, the Company advanced early works and key essential infrastructure activities at the Project. These activities continued to progress at a slower rate than scheduled and Geopacific advised on 11 November 2021 that all non-essential activities at the Woodlark Gold Project had been deferred to enable the Company to conduct a review to focus on enhancing project management oversight and to methodically review the impact of weather nd COVID-19 Pandemic related delays, along with the remaining development uncertainties and the consequent impact on the budget. Geopacific has subsequently advised on 3 February 2022 that it has taken further steps which include suspending all detailed engineering and civil works at the Project pending a review of the Company’s strategic options. The suspension of these activities is to preserve cash reserves whilst the Company undertakes its review. |
Latest News | Geopacific launches Woodlark construction December 16, 2019 |
Source:
p. 8,99
Deposit Type
- Volcanic hosted
- Epithermal
- Breccia pipe / Stockwork
Summary:
Woodlark Island (locally known as Muyuw Island) is located on the northern margin of the Woodlark Basin, some 600 km east of Port Moresby.
There are some series of gold deposits at the Woodlark Project: Kulumadau, Busai, Woodlark King, Munasi.
The geology of the island consists of basement Palaeocene-Eocene tholeiitic basalt and sediments (Loluai formation) overlain by mid- Miocene calc-alkaline to shoshonitic volcanics (Okiduse formation), which host the majority of known gold mineralisation. The island is relatively flat, with the highest point, Mt Kabat just 243 m above sea level. Most of the island is covered by a Pleistocene age coral reef formation (Kiriwina formation), masking prospective volcanic sequences.
Busai and Kulumadau are both interpreted as structurally controlled epithermal gold deposits. The deposits show evidence of complex paragenetic assemblages and variable degrees of structural overprint. The main difference between the two deposits is the overwhelming amount of brecciation and cataclasis at Kulumadau as compared to Busai. Both deposits remain open at depth and along strike.
Due to the significant presence of post- mineralisation Kiriwina formation sediments masking much of the prospective geology, very little regional scale exploration exists.
The extensive resource drilling database, geophysical surveys and limited surface exploration all indicate the widespread occurrence of gold mineralisation well outside the defined resources. Major regional structures associated with known gold resources are evident on geophysical images and form the principal targets for exploration.
Summary:
The project will involve open-cut mining of gold reserves at the Kulumadau, Busai and Woodlark King deposits using multi-staged pit designs, with a stripping ratio of 3.9:1 over the life of the mine. Waste rock will be deposited in engineered waste rock dumps located adjacent to each pit.
Mining Plus was engaged to complete the mining components of the DFS, including optimisation, design and scheduling and preparation of a detailed operating and capital cost estimate to enable the generation of an Ore Reserve.
The study has shown that the three mining areas can be developed in a practical sequence to mine 1.1 Moz of gold and provide sufficient feed to the processing plant for 13 years.
The optimisation resulted in four discrete pits, two at Woodlark King and one each at Busai and Kulumadau.
Individual designs were completed for each discrete area of Busai and Kulumadau, plus a number of starter pits were designed to allow reduced pre-strip durations and the early access to high grades ore.
Mine Schedule.
The mine schedule was developed to ensure 2.4 Mtpa of ore is available to feed the processing plant once commissioned.
The initial pre-strip period is 9 months and involves the stripping of 5.5 Mt from Stage 1 and Stage 2 pits at Kulumadau and the build-up of 450,000 tonnes of ore on the stockpile at 1.45 g/t Au.
The planned mining rates are maintained below 10 Mtpa for the first three years of mining and then rise to 20 Mtpa by the sixth year. These mining rates are driven by the tonnage and grade requirement to ensure that the mine plan achieves gold production levels in excess of 100,000 oz per year for as long as practical.
The mining period is expected to last approximately 9 years excluding pre-stripping operations, however there is an additional four years of low grade stockpile reclaim after mining has been completed.
Flow Sheet:
Crusher / Mill Type | Model | Size | Power | Quantity |
Jaw crusher
|
|
|
|
1
|
SAG mill
|
|
|
|
1
|
Ball mill
|
|
|
|
1
|
Summary:
Primary - jaw crusher.
The grinding circuit comprising a SAG mill and a ball mill in closed circuit with hydrocyclones.
The grinding circuit is fed directly from the primary crusher, i.e. there is no coarse ore stockpile or surge bin to decouple the grinding circuit and the crushing circuit. The plant utilisation factor has been set accordingly. An emergency feed hopper has been included to allow temporary feeding of the mill in the event of crusher downtime.
The SAG mill and ball mill sizes and installed power are reflective of several similar sized mills installed by Lycopodium in remote locations, which provides confidence in manufacturing and proven engineering.
The balance of equipment will be conventional and the nominated manufacturers have provided satisfactory service and performance in several successful Lycopodium projects of similar style, scope and scale.
The plant layout has allowed for possible future installation of pebble crushing.
Processing
- Gravity separation
- Dewatering
- Carbon in leach (CIL)
- Elution
- Carbon adsorption-desorption-recovery (ADR)
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
Flow Sheet:
Summary:
The process plant design for the Woodlark Gold Project is based on a robust metallurgical flowsheet designed for optimum recovery with minimum operating costs. The flowsheet is based upon unit operations that are well proven in industry.
The treatment plant design incorporates the following unit process operations:
• Gravity gold recovery and treatment of concentrate by cyanidation and electrowinning.
• A CIL circuit to leach and adsorb gold and silver onto carbon.
• A pressure Zadra elution circuit, electrowinning and gold smelting to doré.
• Dewatering of CIL tails slurry.
• Tailings slurry pumping via overland pipe to a deep sea tailings placement facility.
The plant design has been based on a nominal capacity of 2.4 Mtpa of the Woodlark ore type.
Recoveries & Grades:
Commodity | Parameter | Avg. LOM |
Gold
|
Head Grade, g/t
| 1.11 |
Projected Production:
Commodity | Units | Avg. Annual | LOM |
Gold
|
koz
| 100 | 967 |
All production numbers are expressed as metal in doré.
Operational Metrics:
Metrics | |
Stripping / waste ratio
| 3.9 * |
Waste tonnes, LOM
| 118.9 Mt * |
Ore tonnes mined, LOM
| 30.3 Mt * |
Total tonnes mined, LOM
| 149.2 Mt * |
Plant annual capacity
| 2.4 Mt * |
Tonnes processed, LOM
| 30.3 Mt * |
Annual mining rate
| 10 Mt * |
Annual ore mining rate
| 2.4 Mt * |
* According to 2018 study.
Reserves at November 7, 2018:
Cut off grade at a 0.4 g/t.
Category | Tonnage | Commodity | Grade | Contained Metal |
Proven
|
18.6 Mt
|
Gold
|
1.17 g/t
|
697 koz
|
Probable
|
10.4 Mt
|
Gold
|
1.02 g/t
|
340.6 koz
|
Proven & Probable
|
28.9 Mt
|
Gold
|
1.12 g/t
|
1,038 koz
|
Measured
|
21.24 Mt
|
Gold
|
1.1 g/t
|
754 koz
|
Indicated
|
18.94 Mt
|
Gold
|
0.98 g/t
|
597 koz
|
Inferred
|
6.8 Mt
|
Gold
|
1 g/t
|
222 koz
|
Total Resource
|
47 Mt
|
Gold
|
1.04 g/t
|
1,573 koz
|
Corporate Filings & Presentations:
Document | Year |
Press Release
|
2022
|
...................................
|
2021
|
...................................
|
2021
|
...................................
|
2021
|
...................................
|
2020
|
Feasibility Study Report
|
2018
|
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News:
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