Overview
Stage | Preliminary Economic Assessment |
Mine Type | Open Pit |
Commodities |
|
Mining Method |
|
Processing |
- Carbon re-activation kiln
- Smelting
- Agitated tank (VAT) leaching
- Carbon in pulp (CIP)
- Carbon adsorption-desorption-recovery (ADR)
- Elution
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
|
Mine Life | 7 years (as of Jan 1, 2020) |
Latest News | ATAC Files Tiger PEA Technical Report and Releases Project Animation April 9, 2020 |
Source:
p. 18
The Property comprises 3,315 contiguous quartz mineral claims that are 100% owned by ATAC, totaling 665.9 km2 (66,590 ha). There are no underlying royalties on the Property.
Deposit Type
- Sediment-hosted
- Carbonate replacement
- Vein / narrow vein
Summary:
Several types of mineralization are known to occur on the Property including:
1. sediment-hosted replacement-style gold
2. zinc ± silver ± lead ± gold ± bismuth in limonite-rich veins and replacement bodies
3. scheelite in tremolite skarns
4. pyrrhotite ± scheelite ± chalcopyrite in actinolite-diopside ± garnet skarns
5. wolframite ± tantalite in granite
6. gold bearing quartz-boulangerite veins
7. pyrite-sphalerite-galena in carbonate replacement deposits.
Sediment-hosted replacement style gold mineralization is the most significant economic mineralization explored on the Property to date. Known showings of this type include the Tiger Deposit.
The Tiger Deposit is located 3 km west-northwest of the Rackla Pluton in a moderate to steep walled valley. It consists of a thick northwesterly trending body of carbonate replacement style gold mineralization hosted by a variably northeast dipping horizon. It has been delineated for about 900m along strike and about 400m in dip extent. The mineralization occurs in multiple zones over an aggregate thickness of up to about 150m. Mineralization is developed within and adjacent to a regionally extensive corridor of highly strained rocks that are manifested as a 40 to 150 m wide zone of small-scale folding and shearing. The geometry of the mineralized system is defined by a series of stacked and folded carbonate horizons intercalated with locally extensive mafic flows and volcaniclastic units.
Most of the exploration at the Tiger Deposit has been directed toward the Discovery Horizon, although there is evidence of at least one additional stratabound interval of gold mineralization above the Discovery Horizon.
Due to a combination of topography, overburden and stratigraphic orientation, the Discovery Horizon is the only mineralized horizon observed at surface. It is exposed over a 75 m long by 10 m wide area on the east side of Tiger Creek. At the northeast end of this exposure, a hand trench dug in 2009 uncovered moderately oxidized limonite boxwork with remnant sulphide mineralization, capped by highly sericite altered volcaniclastic unit. Two samples of sub crop collected in 2008 from near this trench returned 22.5 g/t gold, greater than 1% arsenic, 415 ppm bismuth, and 116 ppm tungsten; and 13.6 g/t gold, greater than 1% arsenic, 410 ppm bismuth, and 51.9 ppm tungsten.
Gold occurs in both sulphide and oxide facies mineralization at the Tiger Deposit. Sulphide mineralization is accompanied by, and developed within, limestone that is replaced by ferruginous dolomite and iron carbonate minerals. Sulphide species consist of disseminated to banded pyrite, with subordinate arsenopyrite and pyrrhotite and minor bismuthinite and sphalerite. Variable amounts of disseminated scheelite are also present. The main sulphide minerals exhibit at least three stages of mineralization.
Oxide mineralization contains weakly disseminated scheelite and is completely devoid of all sulphide minerals. The oxidized rock ranges from very competent, weakly porous limonitic mud to rubbly porous limonitic grit. It appears texturally amorphous within most intersections but occasionally exhibits residual color banding that may represent relict sulphide textures. Complete oxidation extends up to 150 m from surface. The highestgrade and deepest oxidation occurs where northerly trending extensional faults intersect the northwest trending regional shear structure. Detailed observations predominantly collected from drill core on site are described below with respect to pre-mineralizing ground preparation and sulphide/oxide paragenesis. Much of this work is based on paragenetic studies conducted by Eric Theissen for his Master’s thesis (Theissen 2013).
The overall character of the oxide zone is partial to complete destruction of primary features and rarely preserved secondary features. The oxide is a combination of siderite, goethite and limonite (potentially more phases) that vary from moderately hard competent sections to gritty- clay to silt rich rubble. Oxide colour varies from deep red to bright orange-rust to dark brown in color.
Transition zones of oxide to sulphide where the rock has not undergone complete destruction, support first order observations that can be made on general paragenesis. Non-oxidized rock is often equivalent to Tiger Deposit sulphide mineralization with minor but important differences. Typically the ankerite and phase three minerals are present; however there is usually a depletion of arsenopyrite accompanied by strong iron staining throughout. Strongly oxidized portions may show a fine-grained diffuse pyrite (pyrite-2?) that is resistant to the oxidation. Brittle core axis parallel fractures occur more frequently in these sulphide-oxide transition zones and are thought to be attributed to a higher fracture density proximal to the late north trending structures.
Summary:
The open pit mine will utilize a conventional truck-and-excavator fleet. Based on the geotechnical recommendations provided by Golder(2016),blasting will be performed on non-oxide rock only, while oxide material will be excavated directlyby a hydraulic excavator.
Pit optimization and production scheduling were completed using the Measured, Indicated and Inferred Oxide and SulphideMineral Resources. The Project’s LOM is approximately seven years, including one year of pre-stripping followed by six years of mill production. Over the seven-year LOM, the pit will produce 2.7 Mt of mineralized material and 14.4 Mt of waste rock. The overall LOM average gold grade of oxide and sulphide material is 3.82 g/t. The LOM stripping ratio (defined as waste material mined divided by mineralized material mined) is 5.3.
Mining operations will be performed using leased mining equipment. Small mining equipment with operating flexibility was selected to match the pit production schedule and the nature of site. The equipment selection, sizing, and fleet requirements were based on anticipated site operating conditions, haulage profiles, cycle times, and overall equipment utilization. In determining the number of units for major equipment such as drills, excavators, and trucks, annual operating hours were calculated and compared to the available hours for the equipment. Mine support equipment, such as track dozers, motor graders, water/sanding trucks, etc., was matched with the major mining equipment.
Flow Sheet:
Crusher / Mill Type | Model | Size | Power | Quantity |
Sizer
|
|
|
|
1
|
SAG mill
|
|
14' x 8.5'
|
470 kW
|
1
|
Ball mill
|
|
11' x 14.5'
|
665 kW
|
1
|
Summary:
PRIMARY CRUSHING
The crushing facility will have an average process rate of200t/h. Since the mill feed is anticipated to be soft with a significant amount of fines, a mineral sizer is proposed for the primary crushing.
The ROM materials will be trucked from the proposed open pit to the plant site and stockpiled in the ROM receiving pad. The stockpiled materials will be reclaimed by a loader to a loading hopper and conveyed to the sizer. The material will be reduced to 80% passing approximately 120mm by the sizer.
The primary crusher product will be conveyed to the SAG feed surge bin. The crushing circuit will be operated during the day shift only.
The primary crushing area will be equipped with a dust control system to mitigate fugitive dust generation during unloading, crushing,and loading.
MILL FEED SURGE BIN
The crushed materials will be fed to a SAG mill feed surge bin having a live capacity of 1,500t. The crushed material will be reclaimed from the bin by a belt feeder at a nominal rate of 68t/h onto a belt conveyor to feed the primary grinding circuit.A dust control system will be installed in the area to mitigate fugitive dust generation.
PRIMARY GRINDING,CLASSIFICATION
A SAG mill/ball mill circuit is proposed for primary grinding. The primary grinding circuit will consist of a SAG mill and a ball mill in a closed circuit with classifying hydrocyclones. Grinding will be conducted as a wet process at a nominal rate of 68t/h.
The grinding circuit willinclude:
• one SAG mill, 4.27m diameter by 2.59m long (14ft by 8.5ft) (effective grinding length), driven by a 470kW variable frequency drive
• one ball mill, 3.35m diameterby 4.42m long (11ft by 14.5 ft) (effective grinding length), powered by a 665kW fixed speed drive
• two hydrocyclone feed slurry pumps
• two 200mmhydrocyclones
• one particle size analyzer.
The crushed material from the surge bin will be reclaimed onto a belt conveyor that feeds the crushed material to the SAG mill. The SAG mill will be equipped with 40mm pebble ports to discharge the fine fraction from the SAG mill. The SAG mill discharge will be classified by a trommel screen that is integrated with the SAG mill. The trommel screen will have an opening of 9.5mm (slot wide). The oversize from the trommel screen will be transported by belt conveyors back to the SAG mill feed conveyor. The screen undersize will discharge by gravity to the hydrocyclone feed pump box in the grinding circuit. Provisions have been made to provide sufficient space in the grinding area to accommodate a pebble crushing circuit if required at a later date.
The ballmill will be operated in closed circuit with hydrocyclones. The hydrocyclone underflow will flow by gravity to the ball mill feed chute and the ball mill discharge will be combined witht he SAG mill trommel screen undersize slurry and pumped to the hydrocyclones for classification.The circulating load to the ball mill will be approximately 200 to 300%. The particle size of the hydrocyclone overflow, or the final product of the primary grind circuit, will be 80% passing 75µm. The pulp density of the hydrocyclone overflow slurry will be approximately 30% w/w solids.
Grinding media will be manually added into the mills on a batch basis.Dilution water will be added to the grinding circuit as required and lime slurry will be added to the mill to adjust the slurry pH. A particle size analyzer will be installed to monitor and optimize the operating efficiency of the grinding circuit.
Processing
- Carbon re-activation kiln
- Smelting
- Agitated tank (VAT) leaching
- Carbon in pulp (CIP)
- Carbon adsorption-desorption-recovery (ADR)
- Elution
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
Flow Sheet:
Summary:
The proposed 1,500 t/d processing plant will utilize conventional crushing, grinding, cyanidation by carbon-in-pulp (CIP), and gold recovery from loaded carbon to produce gold doré from the Tiger mineralization. Although previous heap leach test work showed promising results from oxide mineralization, and extensive engineering studies were conducted using a combined heap leach and tank processing treatment to extract the gold from the mineralization, there are numerous potential technical risks and challenges associated with the heap leach option. Therefore, a conventional cyanidation circuit consisting of grinding and agitated cyanide leaching for both the sulphide and oxide resources is proposed for this study.
The process plant will co-process two types of mineralization: oxide mineralization and sulphide mineralization. The overall design philosophy was to select proven equipment, with a simple and single line flowsheet that can be operated and maintained effectively in ........

Recoveries & Grades:
Commodity | Parameter | Avg. LOM |
Gold
|
Recovery Rate, %
| 80.8 |
Gold
|
Head Grade, g/t
| 3.82 |
Projected Production:
Commodity | Units | Avg. Annual | LOM |
Gold
|
koz
| 44 | 267 |
All production numbers are expressed as metal in doré.
Operational Metrics:
Metrics | |
Stripping / waste ratio
| ......  |
Waste tonnes, LOM
| ......  |
Ore tonnes mined, LOM
| ......  |
Total tonnes mined, LOM
| ......  |
Daily processing capacity
| ......  |
Tonnes processed, LOM
| ......  |
Annual processing capacity
| ......  |
* According to 2020 study.
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Reserves at January 3, 2020:
Mineral Resources are reported at a 0.75g Au/t cut-off for open pit material and a 1.5g Au/t cut-off in underground material.
Category | Tonnage | Commodity | Grade | Contained Metal |
Measured & Indicated
|
4,526,000 t
|
Gold
|
3.19 g/t
|
464 koz
|
Measured & Indicated
|
4,526,000 t
|
Tungsten
|
221 ppm
|
1,000 t
|
Inferred
|
165,000 t
|
Gold
|
2.17 g/t
|
11.5 koz
|
Inferred
|
165,000 t
|
Tungsten
|
109 ppm
|
18 t
|
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