Overview
Stage | Permitting |
Mine Type | Open Pit |
Commodities |
|
Mining Method |
|
Processing |
- Heap leach
- Carbon in column (CIC)
- Carbon adsorption
- Cyanide (reagent)
|
Mine Life | 6 years (as of Jan 1, 2015) |
Latest News | Lincoln Gold Update for the Pine Grove Gold Project November 22, 2021 |
Source:
Lincoln Gold Mining Inc. is an advanced-stage gold mine exploration and development company holding a 100% interest in the Pine Grove Gold Project.
Summary:
The Pine Grove Property is located within the Walker-Lane mineral trend. According to Stone (2008), the style of mineralization encountered at the Pine Grove project most closely resembles the “Shear Zone” subtype of the “Plutonic-Related Au Quartz Veins and Veinlets L02” deposit type as described by Lefebure and Hart (2005). In particular, the gold mineralization at the Pine Grove project has the following features in common with the “Plutonic-Related Au Quartz Veins and Veinlets L02” deposit type:
Commonly found in tectonic settings of continental margin sedimentary assemblages where intruded by plutons behind margin arcs. Typically developed late in the orogeny or post-collisional settings.
Host rocks are equigranular granodiorite with associated, highly differentiated, porphyritic dikes.
Mineralization can be divided into intrusion-related, epizonal, and shear veins. Intrusionrelated mineralization typically occurs in widespread sheeted vein arrays parallel to the major structural trends. Veins are commonly just hairline fractures to a few centimeters wide and hosted by extensional shears. Veins contain native gold, pyrite, chalcopyrite, and pyrrhotite. Gangue consists of quartz, and sulfides comprise less than 3 percent of the veins. Epizonal mineralization is typically less focused and may be disseminated or occur as replacements. The shear-vein style of mineralization may occur in fault zones outside of the pluton.
Alteration consists of biotite, albite, and sericite, and is spatially restricted to the mineralized zone.
Veins occur close to the associated granite dikes.
Mineralization within the quartz vein and stockwork zones occurs in relatively small tonnage but at relatively higher (2.042 opt) grades. Epizonal deposits have gold grades of 0.058 to 0.146 opt. Combined, these two styles of mineralization can form deposits of ten to hundreds of millions of tons.
Known gold mineralization at the Pine Grove project is found at the Wheeler and the Wilson mines. The two areas show similar alteration and mineralization characteristics but differ in their structural signatures due to differing locations relative to the Pine Grove fault. Gold is found in transitional quartz veins and in thin, crosscutting pyritechalcopyrite stockwork veinlets; the transitional quartz veins occurred between prograde potassic and albitic alteration and retrograde sericite-pyrite-quartz alteration (Jackson, 1996). Dilles (1990) reports that sulfide mineralization is also disseminated.
Hydrothermal alteration consists of early, prograde, high-temperature potassic alteration (biotization and potassium feldspar replacement), followed by an albititc (sic) alteration event, then a transitional chlorite-actinolite event that hosts the gold mineralization. The chlorite-actinolite alteration is confined to the mineralized block between the Stonehouse and Pine Grove faults. Mineralization was followed by retrograde quartz-sericite-pyrite alteration. The alteration events are telescoped and overlap each other, and for the most part are restricted to the mineralized block of granodiorite.
Summary:
Hydraulic excavators and rubber-tired front-end loaders were chosen as primary loading units. The loading units were matched to the contractor specified 100-ton haul trucks. This equipment is a good match for the size of the conceptual pits. Initial pit development may be performed using same equipment fleet as specified for production mining.
In general, backfilling of the Wheeler pit is considered economically and environmentally appropriate. Since the Wheeler Pit would conceptually be mined first, it would probably be backfilled with waste from the Wilson pit. As mining progresses, a minor quantity of fill material may be required on a bench by bench basis to provide temporary ramps in areas with difficult access. Access ramps to the upper levels of the pits would mainly be internal to the pits and would be mined out as the pit progresses downward.
The Wheeler Pit would conceptually be mined out at the beginning of Year 3. The Wilson Pit would be completed during the third quarter of Year 4. Crusher feed is assumed to be 80,000 tons per month. Contractor production will be about 275,000 total tons per month for the first twelve months of mining and then will increase to approximately 300,000 total tons per month through the remainder of the mine life.
Flow Sheet:
Processing
- Heap leach
- Carbon in column (CIC)
- Carbon adsorption
- Cyanide (reagent)
Flow Sheet:
Summary:
The facilities for the Pine Grove Project will be designed to process up to 1.5 million tons of mineralized material to the crusher annually, with an average of 1.0 million tons scheduled in the mine plan. The sources of mineralized material consist of approximately 1.9 million tons from the Wheeler area, 1.6 million tons from the Wilson area. Potentially there is additional mineralized material available from the old underground waste stockpiles, waste dumps and tailings but there is not enough information available to include them at this time. Lincoln would ship loaded carbon from the column cells to an offsite refinery. The major operations required to process the material include:
-Crushing, screening, agglomeration, and heap stacking
-Heap leaching
-Carbon Adsorption
The material will be leached with a dilute sodium cyanide solution on a heap leach pad. Gold will be recovered from the collected pregnant leach solution in activated carbon columns.
Recoveries & Grades:
Commodity | Parameter | Avg. LOM |
Gold
|
Recovery Rate, %
| 75 |
Gold
|
Head Grade, oz/ton
| 0.04 |
Projected Production:
Commodity | Units | LOM |
Gold
|
oz
| 100,623 |
Operational Metrics:
Metrics | |
Daily milling capacity
| 3,300 tons of ore * |
Waste tonnes, LOM
| 10,475 k tons * |
Ore tonnes mined, LOM
| 3,374 k tons * |
Total tonnes mined, LOM
| 13,849 k tons * |
Tonnes milled, LOM
| 3,374 k tons of ore * |
Annual production capacity
| 27 koz of gold * |
* According to 2015 study.
Reserves at September 12, 2019:
Category | Tonnage | Commodity | Grade | Contained Metal |
Indicated
|
5,888,107 tons
|
Gold
|
0.036 oz/ton
|
210,962 oz
|
Inferred
|
43,450 tons
|
Gold
|
0.03 oz/ton
|
1,324 oz
|
Commodity Production Costs:
| Commodity | Units | Average |
Cash costs
|
Gold
|
USD
|
843 / oz *
|
Assumed price
|
Gold
|
USD
|
1,425 / oz *
|
* According to 2015 study / presentation.
Operating Costs:
| Units | 2015 |
Processing costs ($/ton milled)
|
USD
| 13.9 * |
* According to 2015 study.
2015 Study Costs and Valuation Metrics :
Metrics | Units | LOM Total |
Pre-Production capital costs
|
$M USD
|
......
|
Total CapEx
|
$M USD
|
......
|
G&A costs
|
$M USD
|
10.2
|
Total OpEx
|
$M USD
|
......
|
Royalty payments
|
$M USD
|
......
|
Gross revenue (LOM)
|
$M USD
|
......
|
Net revenue (LOM)
|
$M USD
|
......
|
After-tax Cash Flow (LOM)
|
$M USD
|
......
|
After-tax NPV @ 5%
|
$M USD
|
......
|
After-tax IRR, %
|
|
......
|
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Mine Management:
Job Title | Name | Phone | Email | Ref. Date |
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Feb 2, 2021
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