Overview
Stage | Restarting |
Mine Type | Open Pit |
Commodities |
|
Mining Method |
|
Processing |
- Carbon re-activation kiln
- Smelting
- Agitated tank (VAT) leaching
- Carbon in leach (CIL)
- Carbon in pulp (CIP)
- Elution
- Carbon adsorption-desorption-recovery (ADR)
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
|
On-Site Camp |
70 people Source:  |
Mine Life | 4.8 years (as of Jan 1, 2022) |
On June 13, 2022, Bonterra Resources Inc. released the highlights on an independent preliminary economic assessment (“PEA”) on the Barry open pit project in the Urban-Barry Camp in northern Quebec.
Open pit outlines the fastest and cheapest potential production re-start. |
Latest News | Bonterra Executes Definitive Option Agreement with Osisko Mining on Bonterra's Urban-Barry Property November 28, 2023 |
Source:
p. 4
Bonterra acquired the Properties by virtue of a court-approved plan of arrangement completed on September 4, 2018, whereby Bonterra acquired all the issued and outstanding common shares of Metanor Resources Inc. (Metanor).
On January 1, 2020, the Company amalgamated the parent Company with its wholly owned subsidiary Metanor Resources Inc.
Contractors
Contractor | Contract | Description | Ref. Date | Expiry | Source |
unawarded or unknown
|
Mining
|
Bonterra plans to use contractor services for all aspects of the open pit mining.
Drilling and blasting operations will be carried out by a mining contractor experienced in this type of work.
|
Jul 1, 2022
|
|
|
Source:
p.61-62,64,66
Summary:
The Properties are thought to be prospective for greenstone-hosted quartz carbonate vein gold deposits, intrusion related gold (IRGS) deposits, and volcanogenic massive sulphide (VMS) deposits (Darling and Lafontaine (2011), SGS (2019b)). The deposits at the Properties for which Mineral Resources have been estimated are characterized as Greenstone-hosted quartz carbonate veins typical of the northern portion of the Abitibi Subprovince of the Superior Province in northwestern Québec.
The Barry property is underlain by greenschist facies volcanic and intrusive rocks of tholeiitic affinity belonging to the UBGB. As there is limited outcrop exposure, the geology had to be deduced from drill holes data and geophysics. Geological mapping and diamond drilling identified a series of basaltic flows that are interpreted to cover over 90% of the Barry property. The only intrusive bodies identified on the Barry property were the quartz-feldspar porphyry in the area of the Barry I Main Zone Area and a series of gabbro sills to the north. A siltstone outcrop was identified approximately 300 m northeast of the Barry I Main Zone. Stratigraphic tops are to the southeast, as indicated by pillow facing directions. The rocks on the Barry property are overprinted by a weak to moderate northeast to southwest trending foliation (S2) that parallels regional shearing and contacts of the large granitic intrusions.
Mafic volcanic rocks are the most common rocks on the Barry property and consist of dark green, fine grained, iron-rich tholeiitic basalts. In order of decreasing abundance, these flows vary from massive, amygdaloidal, brecciated, feldspar-phyric, to locally pillow. Alteration varies from a regional chlorite alteration to carbonate, sericite, epidote plus minor silicification, hematization, biotite and actinolite alteration locally (Tessier 1996, Lariviere 1997). All these rocks vary from generally nonmagnetic to locally strongly magnetic with up to 5% disseminated magnetite crystals and less commonly stringers of magnetite.
Mafic volcanic rocks in the area of the Barry deposit are intruded by a series of porphyritic to granitic felsic dikes or sills. The quartz-feldspar porphyry varies in colour from a medium grey (fresh surface), to a reddish tint (due to hematization), to a bleached light grey (due to strong silicification). The quartzfeldspar porphyry is noted to be sill like, maintaining a general stratigraphic position within the volcanic pile, while simultaneously crosscutting the volcanic stratigraphy on surface. The thickness of this unit varies from several metres to over 125 m.
One can observe two sets of porphyritic to granitic felsic dikes or sills. The first set is foliated and exhibits 35% of feldspars and less than 5% of blue quartz-eyes. The second set of quartz-feldspar porphyry is not foliated and contains 8% to 12% of blue quartz-eyes and 50% of feldspars.
The gabbro is massive, medium to coarse grained with a dark green colour. At times, the gabbro develops a finer grained gradational contact with the basalts and varies from moderately to nonmagnetic. Drilling indicates that the gabbro is sill like and up to 20 m thick.
Gold mineralization is constrained to zones containing 5% to 15% albite-carbonate-quartz veins and their associated hydrothermally altered wall rocks (SGS, 2019a). Albite-carbonate-quartz veins are typically one centimetre to five centimetres wide, and comprise euhedral albite, carbonate, and quartz with local trace biotite ± sericite, chlorite, pyrite (fine grained anhedral, or coarse grained euhedral), pyrrhotite, rare euhedral magnetite, and fine grained visible gold as inclusions or fracture infill in pyrite, or in sharp contact with carbonate crystals in the vein. Veins locally pinch and swell or are boudinaged with biotite generally filling the cusps. Gold grades in mineralized veins and altered mafic volcanic rocks range from less than 2 g/t Au to more than 100 g/t Au.
The following alteration types have been observed on the Barry property:
• Syn-ore carbonate-quartz-pyrite alteration associated with the mineralized albite-carbonatequartz veins.
• Syn-ore biotite-calcite alteration associated with mineralized albite-carbonate-quartz veins in areas of intense foliation.
• Post-ore biotite-chlorite, carbonate, muscovite, and epidote alteration. Post-ore epidote alteration is generally found at depths greater than 25 m, where it is commonly associated with epidote-garnet veinlets, or in non-mineralized zones at shallower depths.
Source:
p.174,177,180-181
Summary:
The mineralized material extending from the surface to a depth of approximately 106 m for Pit 1 will be mined by conventional open pit methods. Pit 1 contains 91% of the open pit constrained Mineral Resource, with Pits 2 and 3 containing the balance which will be mined early in the life of mine (LOM). The stripping ratio has been estimated at approximately 5.37:1 over the LOM period. Mining has been carried out in the past, hence, bench faces are available to permit a rapid start-up. Waste rock material will be stockpiled at designated areas while mineralized material will require little stockpile area as this material will be transported to the process plant at the Bachelor mine site daily. Transport to the processing facility will be by contractor haulage using 50 t trucks via secondary gravel roads maintained for the purpose. Production is scheduled at 1,200 tpd for an average annual production of 420,000 t, while annual mined waste rock material will average 2.1 million tonnes (Mt). Bonterra plans to use contractor services for all aspects of open pit mining.
Drilling will be carried out on a two shift per day basis, requiring on average two drill rigs over the LOM, with an additional unit provided as required. Since the mineralized material will require long-distance haulage by a local contractor, initial good fragmentation of the mineralized material is very important to reduce potential damage to the contractor’s truck boxes. A crusher will be installed on site to crush the mineralized material to approximately 150 mm to 200 mm for efficient loading. Additionally, it is planned to use a tighter drilling pattern of 2.7 m x 3.0 m to maintain adequate initial fragmentation, however, this pattern may be adjusted as operating experience is acquired. Drill holes of 89 mm diameter will be used, with one meter of subgrade to ensure efficient mucking. Drilling of the mineralized material will require approximately 22,500 m annually to produce 420,000 t of material. A factor of 15% was used for redrilling requirements.
Drilling for the waste rock material will be carried out using 115 mm to 120 mm diameter holes drilled on a 3.5 m x 3.5 m pattern, which will require approximately 65,000 m annually to achieve a maximum production rate of 2.38 Mt of waste.
Drilling will be carried out using a FlexiRoc T-45 or equivalent drill rig with a manufacturer recommended hole depth of 29 m to 35 m. Pre-splitting will be used on the final pit walls to control the slope of the walls.
Blasting operations for the Barry pit are planned to be carried out by a contractor who will also provide all blasting supplies. The blasting contractor will provide a transfer plant to be installed on the mine site that will be capable of producing sufficient bulk explosives plus accessories to carry out all blasting operations. The contractor will also provide the personnel for the bulk plant, lead and helper blasters and mechanics, plus the necessary equipment required to carry out the loading and blasting of the mineralized material and waste rock material. The transfer plant will be installed at a safe distance from any infrastructure, as per provincial regulations. SLR recommends further analysis in future studies to optimize the blasting operations.
Loading and pit haulage operations will be carried out using a Cat 980 or equivalent front-end loader combined with Cat 745 articulated trucks with a 40 t rated payload. A Cat 349 or equivalent excavator will also form part of the open pit fleet.
The average daily haulage will be approximately 8,000 tpd over the LOM. There will be additional movement of overburden and waste rock material in the first year to prepare for future mining. The mining contractor will be responsible for operating and servicing their equipment.
The waste stockpile locations are placed as near the open pit as possible to reduce the haulage distances. Further analysis of the final locations of the waste rock stockpile should be carried out in future studies.
A service building will be provided by Bonterra that will have sufficient bays to permit efficient maintenance to be carried out on all the site equipment. Bonterra plans to use the facility for the future potential underground mining fleet maintenance.
Open Pit Design
The open pit was designed using benches, safety berms, and ramps. These design parameters combine to determine what the overall pit wall angles will be and determine the amount of waste rock material that must be removed to enable safe and efficient extraction of the mineralized material.
Slope and Bench Configuration:
Pit 1:-
- Bench Height (Double Benching 5 m) - 10 m;
- Berm Width - 5.4 m.
Pit Wall with Ramp:
- Bench Face Angle - 75°;
- Inter-Ramp Angle (IRA) - 51°;
- Overall Slope Angle (OSA) - 45°.
Pit Wall Without Ramp
- Bench Face Angle - 65°;
- Inter-Ramp Angle (IRA) - 45°;
- Overall Slope Angle (OSA) - 45°.
Pits 2 and 3:
- Bench Height (Double Benching 5 m) - 10 m;
- Berm Width - 5.4 m.
Pit Wall with Ramp:
- Bench Face Angle -75°;
- Inter-Ramp Angle (IRA) - 51°;
- Overall Slope Angle (OSA) - 40° to 45°.
Ramp Design
The average ramp grade was designed at 10%, however, it will steepen up to 12% when the bottom most benches are mined. According to provincial regulations with regards to occupational health and safety in mines, the design of the rolling surface of the haulage ramp shall be three times the width of the largest vehicle for two-way traffic and twice the size for single lane traffic. The service road shall be edged by a pile of fill or ridge (the berm) having a height equal to at least the radius of the largest wheel of any vehicle travelling the road.
Ramp Design Parameters:
2-Way Traffic:
- Protection Berm Width (Tire Height) - 3.4 m;
- Operating Width (3 x Truck Width) - 11.5 m;
- Back Break- Allowance - 1 m;
- Ditch- Allowance - 1 m;
- Total Width - 17 m.
1-Way Traffic:
- Protection Berm Width (Tire Height) - 3.4 m;
- Operating Width (2 x Truck Width) - 7.6 m;
- Back Breaking - 1 m;
- Ditch - 1 m;
- Total Width - 13m.
Source:

- subscription is required.
Processing
- Carbon re-activation kiln
- Smelting
- Agitated tank (VAT) leaching
- Carbon in leach (CIL)
- Carbon in pulp (CIP)
- Elution
- Carbon adsorption-desorption-recovery (ADR)
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
Flow Sheet:
Source:
p.15,190,195-198
Summary:
The Bachelor Plant is currently on care and maintenance. The Bonterra concentrator is designed for a throughput of 800 tpd. An expansion is planned to increase the throughput to 1,200 tpd feed to accommodate the Barry mineralized material.
The development of the new flowsheet included the existing equipment and the existing building space as much as possible.
Cyanide is added to the grinding circuit to initiate the gold leaching. Hydrated lime is added to the grinding circuit to adjust the pH. The cyclone overflow, which is the final grinding product, is sent to a vibrating trash screen.
The slurry containing the ground material is sent to a thickener to increase the slurry density prior to leaching. Gold leaching is realized in four leach tanks (220 m3 each) in series that allow 18 hours of residence time at 800 tpd to be obtained. The leached slurry is then transferred to four carbon-in-pulp (CIP) tanks, where the gold is adsorbed onto carbon. The CIP circuit has a total capacity of 730 m3 and allows for 17 hours of residence time. The slurry flows by gravity from one tank to another while, the carbon is transferred in countercurrent from tank to tank. At the end of the CIP circuit, the gold depleted slurry that becomes the tails is sent to a carbon safety screen and then pumped to the tailings management facility (TMF).
The gold-loaded carbon is transferred to the loaded carbon screen. Gold is recovered from the loaded carbon in a 3-tonne pressure Zadra elution circuit followed by an electrowinning cell. The elution frequency is approximately one every three days. The gold recovered is further refined and gold doré bars are poured.
Pre-Leach Thickener.
The slurry from the cyclone overflow is transferred to a trash screen to remove any trash carried over with the gold-bearing material before the carbon-in-leach (CIL) circuit. The slurry would then be sent to the existing thickener to increase the slurry density prior to leaching. The existing thickener is a 40-foot conventional thickener. A high rate feed-well will be retrofitted to this thickener to improve the efficiency and guarantee to meet the expected performances when the mill runs at 1,200 tpd.
CIL, Leach, and CIP.
The thickened slurry is sent to the one existing tank (200 m3), where carbon transfer pumps and static screens will be added. This tank will then be modified from a leach tank to CIL. The CIL tank allows the adsorption of the gold leached onto activated carbon.
The leaching circuit is composed by the three mechanically agitated tanks (6.7 m each), providing a residence time of eight hours.
The static screen design will be based on custom-made models that are already in use in other gold mills in a CIP circuit. The advantage of these screens is that they do not require space above the tank to be lifted out of the tank for maintenance, as is the case for other interstage screens such as Kemix-type screens. Installation of Kemix screens would not be possible without major modifications to the building as the building does not currently have sufficient clearance above the tanks.
The existing loaded carbon screen will be used to recover the carbon and send it to the elution circuit.
The leached slurry is then transferred to four CIP tanks in series. A carbon pump and a static screen are installed in the tanks and the slurry will flow by gravity from one tank to the next. A safety screen will collect carbon carried over at the CIP tailings to prevent it from being discarded at the TMF.
A total leaching time of 20 hours is recommended, including the CIP. This leach time is considered long enough to process the Barry mineralized material.
Tailings.
The tailings from the Safety Screen undersize are sampled in a new sampler and pumped to the TMF. Natural cyanide degradation will take place in the TMF.
Acid Wash, Elution and Carbon Regeneration.
The existing 3-ton capacity elution circuit is adequate to process the carbon from the CIP circuit even at 1,200 tpd. The elution will be performed at the rate of one elution cycle every two days. The expected loaded carbon grade is over 4 000 g/t.
The sizing of the actual carbon reactivation circuit is appropriate for the increased throughput. The electrowinning capacity is presently considered appropriate. The QP recommends that a new electric induction smelting furnace should be added.
Reagents.
Hydrated lime is currently added directly at the rod mill feed with a screw conveyor. A system for hydrated lime dissolution and distribution is presently considered as a potential improvement.
Sodium cyanide is currently delivered in solution (32%) and the cyanide solution is transferred from a tanker into a cyanide solution distribution tank.
The flocculant used in the thickener is currently prepared manually. An automatic preparation system is necessary with a high-rate thickener. The equipment required includes a bulk bag hopper or a hopper-fed manually with 25 kg bags, a flocculent feeder, and an eductor to obtain a perfectly mixed solution.
The caustic soda is currently received as 50% solution in totes which is appropriate at higher throughput. However, it is planned to install a tank that will be fed directly by a tanker to reduce the operators’ manipulation of this product.
Water and Compressed Air.
The water distribution circuit will include a mill solution tank fed by the thickener overflow and a portion of the water reclaimed from the TMF. The mill solution water contains cyanide and is used in the grinding circuit to form a slurry with the mill feed and further adjust the slurry percent solids. The remainder of the water reclaimed from the TMF is sent to a reclaim water tank. This water will be used as wash water on the linear and vibrating screens and transferred to the carbon water tank. The carbon water is used to transfer carbon during the carbon acid wash and elution. Mine water is collected in the mine water tank and used for the reagent preparation systems and to seal the slurry pump gland. The water system’s capacity is reviewed to meet the high throughput requirements.
Recoveries & Grades:
Commodity | Parameter | Avg. LOM |
Gold
|
Recovery Rate, %
| 95 |
Gold
|
Head Grade, g/t
| 2.36 |
Projected Production:
Commodity | Product | Units | Avg. Annual | LOM |
Gold
|
Payable metal
|
oz
| | 143,599 |
Gold
|
Metal in doré
|
oz
| 30,000 | 145,050 |
Operational Metrics:
Metrics | |
Daily mining rate
| 8,000 t * |
Daily ore mining rate
| 1,200 t * |
Daily processing capacity
| 1,200 t * |
Annual ore mining rate
| 420,000 t * |
Annual processing capacity
| 420,000 t * |
Stripping / waste ratio
| 5.37 * |
Waste tonnes, LOM
| 10,838 kt * |
Ore tonnes mined, LOM
| 2,016 kt * |
Total tonnes mined, LOM
| 12,854 kt * |
Tonnes milled, LOM
| 2,016 kt * |
* According to 2022 study.
Reserves at July 1, 2022:
Open pit Mineral Resources are reported within an optimized pit at a cut-off grade of 1.0 g/t Au, while underground Mineral Resources are reported within underground reporting shapes defined using a minimum thickness of 1.2 m and a cut-off grade of 2.6 g/t Au, limited to areas of continuous mineralization.
Category | OreType | Tonnage | Commodity | Grade | Contained Metal |
Measured
|
In-Situ (OP)
|
1,732 kt
|
Gold
|
2.66 g/t
|
148 koz
|
Measured
|
In-Situ (UG)
|
344 kt
|
Gold
|
4.94 g/t
|
55 koz
|
Measured
|
Total
|
2,076 kt
|
Gold
|
3.04 g/t
|
203 koz
|
Indicated
|
In-Situ (OP)
|
184 kt
|
Gold
|
2.87 g/t
|
17 koz
|
Indicated
|
In-Situ (UG)
|
2,839 kt
|
Gold
|
5.15 g/t
|
470 koz
|
Indicated
|
Total
|
3,023 kt
|
Gold
|
5.01 g/t
|
487 koz
|
Measured & Indicated
|
In-Situ (OP)
|
1,916 kt
|
Gold
|
2.68 g/t
|
165 koz
|
Measured & Indicated
|
In-Situ (UG)
|
3,183 kt
|
Gold
|
5.12 g/t
|
524 koz
|
Measured & Indicated
|
Total
|
5,099 kt
|
Gold
|
4.21 g/t
|
689 koz
|
Inferred
|
In-Situ (OP)
|
15 kt
|
Gold
|
2.36 g/t
|
1 koz
|
Inferred
|
In-Situ (UG)
|
4,364 kt
|
Gold
|
4.9 g/t
|
687 koz
|
Inferred
|
Total
|
4,379 kt
|
Gold
|
4.89 g/t
|
689 koz
|
Commodity Production Costs:
| Commodity | Units | Average |
Cash costs
|
Gold
|
USD
|
939 / oz *
|
All-in sustaining costs (AISC)
|
Gold
|
USD
|
1,065 / oz *
|
Assumed price
|
Gold
|
USD
|
1,600 / oz *
|
* According to 2022 study / presentation.
Operating Costs:
| Units | 2022 |
OP mining costs ($/t mined)
|
CAD
| 5.31 * |
OP mining costs ($/t milled)
|
CAD
| 33.9 * |
Processing costs ($/t milled)
|
CAD
| 19.1 * |
G&A ($/t milled)
|
CAD
| 12.3 * |
Total operating costs ($/t milled)
|
CAD
| 81.3 * |
* According to 2022 study.
2022 Study Costs and Valuation Metrics :
Metrics | Units | LOM Total |
Initial CapEx
|
$M CAD
|
22.1
|
Sustaining CapEx
|
$M CAD
|
21.3
|
Closure costs
|
$M CAD
|
6.5
|
Total CapEx
|
$M CAD
|
49.9
|
OP OpEx
|
$M CAD
|
68.3
|
Processing OpEx
|
$M CAD
|
38.5
|
Refining and transportation
|
$M CAD
|
1
|
Transportation (haulage) costs
|
$M CAD
|
32.3
|
G&A costs
|
$M CAD
|
24.9
|
Total OpEx
|
$M CAD
|
163.9
|
Mining Taxes
|
$M CAD
|
11.1
|
Royalty payments
|
$M CAD
|
14.9
|
Gross revenue (LOM)
|
$M CAD
|
306.3
|
Net revenue (LOM)
|
$M CAD
|
290.5
|
Operating margin, %
|
|
41
|
Operating margin (LOM)
|
$M CAD
|
126.6
|
EBITDA (LOM)
|
$M CAD
|
126.6
|
Net Income (LOM)
|
$M CAD
|
72.2
|
Pre-tax Cash Flow (LOM)
|
$M CAD
|
76.7
|
After-tax Cash Flow (LOM)
|
$M CAD
|
65.7
|
Pre-tax NPV @ 5%
|
$M CAD
|
57.3
|
Pre-tax NPV @ 10%
|
$M CAD
|
42.7
|
Pre-tax NPV @ 15%
|
$M CAD
|
31.7
|
After-tax NPV @ 5%
|
$M CAD
|
48.3
|
After-tax NPV @ 10%
|
$M CAD
|
35.3
|
After-tax NPV @ 15%
|
$M CAD
|
25.5
|
Pre-tax IRR, %
|
|
49.1
|
After-tax IRR, %
|
|
43.1
|
Pre-tax payback period, years
|
|
3.2
|
After-tax payback period, years
|
|
3.4
|
Mine Management:
Job Title | Name | Profile | Ref. Date |
Consultant - Mining
|
Varun Bhundhoo
|
|
Jul 1, 2022
|
Consultant - Recovery Methods
|
Pierre Roy
|
|
Jul 1, 2022
|
President and CEO
|
Marc-Andre Pelletier
|
|
Aug 17, 2022
|
Corporate Filings & Presentations:
News: