Overview
Stage | Preliminary Economic Assessment |
Mine Type | Open Pit |
Commodities |
|
Mining Method |
|
Processing |
- Gravity separation
- Leaching plant / circuit
- Carbon in leach (CIL)
- Elution
- Cyanide (reagent)
|
Mine Life | 5.8 years (as of Jan 1, 2016) |
Source:
p. 19, 35
Panoramic Resources has an indirect interest in the Gum Creek Gold Project through its 51% majority shareholding in Horizon Gold Limited (ASX:HRN Horizon).
Deposit Type
- Vein / narrow vein
- Banded iron formation hosted
Summary:
The Gum Creek consists Swan OC/UG, Swift OC/UG, Heron South OP, Howards OP, Specimen Well OP, Toedter OP, Shiraz OP, Kingfisher UG, Wilsons UG deposits.
The Property is located in the Gum Creek Greenstone Belt, within the Southern Cross Province of the Youanmi Terrane, a part of the Archaean Yilgarn craton in Western Australia. The Gum Creek Greenstone belt forms a lensoid, broadly sinusoidal structure approximately 110 km long and 24 km wide. It is dominatedby volcanic and sedimentary sequences and surrounded by intrusive granitoids containing rafts of greenstones. The margins of the belt are typically dominated by contact-metamorphosed basalts and banded iron formations.
Five main styles of mineralisation are recognised in the area:
Quartz-carbonate (±pyrite, pyrrhotite, galena and sphalerite) veins that form complex conjugate vein arrays associated with brittle dilational openings developed along major shears within competent mafic host rocks. Carbonate-sulphide wall-rock alteration is common about mineralised zones and extensive supergene enrichment often overlies the primary mineralisation zones. Typically, free milling and locally high grade (>20g/t Au). Deposits of this type represent the dominant mineralisation type at Gum Creek and include the deposits of Swan Bitter, Swift, Kingfisher and Wyooda/Thangoo.
Ductile shear hosted mineralisation – arsenopyrite dominant. Fine grained gold associated with sulphide rich, intense biotite- sericite altered narrow ductile shear zones. Gold grades are typically in the range 5-10g/t Au. Arsenopyrite and pyrrhotite are the dominant sulphides with most gold locked within the arsenopyrite. Examples of this style of mineralisation are the refractory deposits of Wilsons, Heron South, Snook and Camel Bore.
Ductile shear hosted mineralisation – pyrite dominant. Fine grained gold associated with sulphide poor, broad ductile shear zones developed within mafic host rocks. Shearing typically defined by weak biotite alteration, up to 1% fine pyrite and a sparse network of thin (1-3mm thick) quartz veins. Gold grades are typically in the range 0.5–1.5g/t Au and the mineralisation is free milling. Howards is the representative deposit of this mineralisation style.
BIF hosted mineralisation. Quartz-pyrrhotite veining and pyrrhotite replacement of magnetite meso-bands form narrow steep-plunging shoots of limited length and width but extending to depth. This mineralisation style occurs in fold hinges within banded iron formation marginal to major north-south shear zones and is similar to the Hill 50 mineralisation at Mt Magnet. Grades are typically 1-10g/t Au and the mineralisation is free milling. The Omega deposit is of this style.
Quartz veins. Sulphide poor, sheeted and anastomosing quartz veins and lenses developed in shears straddling granodiorite contacts within the Gum Creek Greenstone Belt. Grades are typically 1-5g/t Au. The Montague deposits, which are free milling, represent this style of mineralisation.
The main style of mineralisation at the two depositsis hosted within quartz- carbonate veining. Complex conjugate veinarrays associated with brittle dilational openings developed along major shears within the competent mafic host rocks. Carbonate-sulphide wall rock alteration is common about mineralised zones and extensive supergene enrichment often overlays primary mineralisation zones.
The Swan Premium Lode is interpreted as a mineralised, north-striking, steeply east- dipping conjugate vein set emanating from the broader north-striking,steeply west- dipping Butcherbird Shear. The Butcherbird Shear is located approximately 50m to 70m east of existing underground development on the Cascade Lode.
The Swift deposit has been interpreted as a flat-lying to shallowly east-dipping structure similar in geology and tenor to the Swan deposit shear zones.
The Butcherbird Shear, Swan Premium Lode, and the flat-lying to shallowly east- dipping Swift structurehave not been interpreted as well-defined structures with sharp edges, but rather zones of silica flooding along poorly-defined, pre-existing structures. Variability in quartz flooding and gold grade within these zones is high adding to the complexity in the mineralisation.
The modelled portion of the Swan deposit consists of 1,450 m of strike in an approximately north-south direction, 600 m across strike, and 620 m down-dip, and open at depth.
The modelled portion of the Swift deposit consist of 850m of strike in an approximately north-south direction, and 300m down-dip, and open at depth.
Summary:
The Study assumed a standard drill, blast, load and haul mining methodology which is well known and widely used in Western Australia.
Mining at Gum Creek will be undertaken by mining contractors, with personnel operating on a fly-in, fly-out out basis from Perth, with local residents employed where possible.
Production from Swan and Swift includes cutbacks to the existing open pits, while mining at Howards will be from a new open pit.
Swan:
- Minimum Mining Width – 4m downhole;
- Internal Dilution – 2m downhole;
- Edge Dilution - 1m either side downhole;
- High Grade Cuts:
- Oxide – 10g/t
- Transitional – 20g/t
- Fresh 200g/t
- Pit Slope angles range from 35-45 degrees;
- Ramp widths range from 12-18m wide with a gradient of 1 in 9;
- Batter angles range from 70 degrees near the base to 55 degrees near the surface and berm heights of 20m with minimum berm widths of 7m.
Swif:
- Minimum Mining Width – 4m downhole;
- Internal Dilution – 2m downhole;
- Edge Dilution - 1m either side downhole;
- High Grade Cuts – Oxide – 20g/t, Transitional – 30g/t, Fresh 30g/t;
- Pit Slope angles range from 40-44 degrees;
- Ramp widths range from 12-18m wide with a gradient of 1 in 9;
- Batter angles range from 70 degrees near the base to 55 degrees near the surface and berm heights of 20m with minimum berm widths of 5m.
Howards:
- Mining dilution – 5%;
- Mining loss – 5%;
- Pit Slope angles were 45 degrees;
- Ramp widths range from 12-18m wide with a gradient of 1 in 9;
- Batter angles range assume 70 degrees and berm heights of 20m with berm widths of 5m.
Processing
- Gravity separation
- Leaching plant / circuit
- Carbon in leach (CIL)
- Elution
- Cyanide (reagent)
Source:
Summary:
The Study is based on mining open pit Resources from the Swan, Swift and Howards Resources and processing it through a new 800ktpa Carbon in Leach (“CIL”) processing plant to produce approximately 290koz gold over an initial six year mine life.
The Gum Creek Gold Project includes a 600,000tpa process facility (not in operation).
Feed from Swan, Swift and Swan South will be hauled to the process plant ROM pad, whilst feed from Howards will be stockpiled and hauled via road train as required. Feed to the process plant will be blended in accordance with the delivery schedule from each open pit.
The comminution and metallurgical flow sheet design was undertaken by an engineering contractor. The design includes three stages of crushing, a single ball mill, gravity circuit, cyanide leach, elution circuit and gold room. The throughput rates for fresh and oxide/transitional ore is 800ktpa and 1Mtpa respectively.
Historical metallurgical recoveries ........

Recoveries & Grades:
Commodity | Parameter | Avg. LOM |
Gold
|
Recovery Rate, %
| ......  |
Gold
|
Head Grade, g/t
| 1.94 |
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Projected Production:
Commodity | Units | Avg. Annual | LOM |
Gold
|
oz
| 60,000 | 290,000 |
All production numbers are expressed as payable metal.
Operational Metrics:
Metrics | |
Stripping / waste ratio
| 9.4 * |
Ore tonnes mined, LOM
| 4.9 Mt * |
Annual processing rate
| 800,000 t * |
* According to 2016 study.
Reserves at June 30, 2019:
Category | OreType | Tonnage | Commodity | Grade | Contained Metal |
Indicated
|
Total
|
11,190,000 t
|
Gold
|
2 g/t
|
|
Inferred
|
Total
|
4,712,000 t
|
Gold
|
4.3 g/t
|
|
Total Resource
|
Total
|
15,890,000 t
|
Gold
|
2.7 g/t
|
1,388,000 oz
|
Commodity Production Costs:
| Commodity | Units | Average |
All-in sustaining costs (AISC)
|
Gold
|
AUD
|
1,209 / oz *
|
Assumed price
|
Gold
|
USD
|
1,275 / oz *
|
* According to 2016 study / presentation.
Operating Costs:
| Units | 2016 |
OP mining costs ($/t milled)
|
AUD
| 35 * |
Processing costs ($/t milled)
|
AUD
| ......  |
Total operating costs ($/t milled)
|
AUD
| ......  |
* According to 2016 study.
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2016 Study Costs and Valuation Metrics :
Metrics | Units | LOM Total |
Initial CapEx
|
$M AUD
|
......
|
Sustaining CapEx
|
$M AUD
|
......
|
Total CapEx
|
$M AUD
|
......
|
Net revenue (LOM)
|
$M AUD
|
......
|
EBITDA (LOM)
|
$M AUD
|
......
|
Pre-tax Cash Flow (LOM)
|
$M AUD
|
......
|
Pre-tax NPV @ 11%
|
$M AUD
|
......
|
Pre-tax IRR, %
|
|
......
|
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Mine Management:
Job Title | Name | Profile | Ref. Date |
.......................
|
|
|
Oct 8, 2020
|
- Subscription is required.
Corporate Filings & Presentations:
- Subscription is required.
Aerial view:
- Subscription is required.