The 2022 technical report for the Barry Open Pit Project describes the existing 800 tpd Bonterra concentrator and a proposed expansion to 1,200 tpd feed for Barry mineralized material.
Report context
The Barry Open Pit Project processing information is documented in the NI 43-101 Technical Report dated July 25, 2022. The report presents recovery methods for the Bonterra concentrator (referred to as the Bachelor Plant), which is designed for an initial throughput of 800 tpd. An expansion to 1,200 tpd is planned to accommodate Barry mineralized material. The new flowsheet was developed to use existing equipment and existing building space as much as possible.
Processing route
Existing equipment and circuit (800 tpd)
The existing equipment can process up to 800 tpd of mineralized material and sometimes higher throughput with a softer feed. The crusher circuit consists of a mobile jaw crusher (50 hp) followed by a standard cone crusher operating in closed circuit with a double-deck screen. A second cone crusher crushes the screen oversize (+3/8 inch) while the undersize is conveyed to a bin.
Fine material is sent to a primary rod mill (400 hp) operating in open circuit. The secondary grinding stage comprises a tricone (535 hp) and two ball mills (150 hp and 100 hp) operating in closed circuit with a cyclone cluster of four 15-inch cyclones. When feed is from Barry, the tricone is used alone as the secondary mill because Barry material has a lower Bond work index. Cyanide is added to the grinding circuit to initiate gold leaching; hydrated lime is added to adjust pH. Cyclone overflow, the final grinding product, goes to a vibrating trash screen.
The slurry is thickened prior to leaching. Gold leaching occurs in four leach tanks (220 m³ each) in series, providing 18 hours of residence time at 800 tpd. Leached slurry moves to four carbon-in-pulp (CIP) tanks with a total capacity of 730 m³, allowing 17 hours of residence time. Slurry flows by gravity between tanks while carbon is transferred countercurrent. Gold-depleted tails pass through a carbon safety screen before being pumped to the tailings management facility (TMF).
Gold-loaded carbon goes to a loaded carbon screen. Gold is recovered in a 3-tonne pressure Zadra elution circuit followed by an electrowinning cell. Elution frequency is approximately once every three days. Gold is further refined and poured as doré bars.
Proposed flowsheet at increased throughput (1,200 tpd)
The existing flowsheet will be modified for 1,200 tpd production. The expansion mainly affects the secondary mill: a tricone will be added to the existing tricone so cyclone underflow is split equally between the two mills. The two smaller ball mills will be removed to install the larger tricone mill.
The report notes that the current plant can process 800 tpd of Barry material without any modifications. For 1,200 tpd, necessary modifications include: adding a second tricone of 535 hp in parallel with the current one; installing a high-capacity feedwell on the current thickener; adding a carbon screen and carbon transfer pump in the first leach tank; modifying or changing slurry pumps to match the new mass balance; and adding a new induction furnace for gold refining.
Crushing circuit
Existing crushing equipment comprises a jaw crusher (50 hp) in open circuit, followed by a standard head cone crusher (200 hp) and a short head cone crusher (200 hp) for secondary and tertiary crushing, both installed in closed circuit with a common double-deck screen. Feed rate is 100 tph. Operating time will be increased from 8 to 12 hours per day to reach 1,200 tpd.
Grinding circuit
The existing rod mill is capable of handling the targeted 1,200 tpd throughput. The secondary grinding stage currently has a single tricone with capacity for 800 tpd. The expansion adds one more tricone to reach 1,200 tpd; the two tricones (535 hp each) will operate in closed circuit with the four-cyclone cluster.
Pre-leach thickening
Cyclone overflow transfers to a trash screen before the carbon-in-leach (CIL) circuit. Slurry is then sent to the existing 40-foot conventional thickener to increase density prior to leaching. A high-rate feed-well will be retrofitted to this thickener to improve efficiency and guarantee expected performance at 1,200 tpd.
CIL, leach, and CIP
The thickened slurry goes to one existing tank (200 m³) where carbon transfer pumps and static screens will be added; this tank will be modified from a leach tank to CIL. The leaching circuit is composed of three mechanically agitated tanks (6.7 m each), providing eight hours of residence time.
Static screen design will be based on custom-made models already in use in other gold mills in CIP circuits. These screens do not require space above the tank for maintenance, unlike Kemix-type screens, which could not be installed without major building modifications due to insufficient clearance above the tanks.
The leached slurry is transferred to four CIP tanks in series. A carbon pump and static screen are installed in each tank; slurry flows by gravity between tanks. A safety screen collects carbon carried over at the CIP tailings to prevent loss to the TMF.
A total leaching time of 20 hours is recommended, including the CIP. This leach time is considered sufficient for Barry mineralized material.
Tailings
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 for the CIP circuit even at 1,200 tpd. Elution will be performed at one cycle every two days. The expected loaded carbon grade is over 4,000 g/t. The carbon reactivation circuit is sized appropriately for increased throughput, and electrowinning capacity is considered appropriate. The qualified person recommends adding a new electric induction smelting furnace.
Reagents
Hydrated lime is currently added directly at the rod mill feed with a screw conveyor; a dissolution and distribution system is considered as a potential improvement. Sodium cyanide is delivered in 32% solution, transferred from tanker to a distribution tank. Flocculant is prepared manually; an automatic preparation system is necessary with the high-rate thickener, including a bulk bag hopper or hopper-fed manual system with 25 kg bags, a flocculant feeder, and an eductor. Caustic soda is received as 50% solution in totes, which is appropriate at higher throughput; a tank fed directly by tanker is planned to reduce operator handling.
Water and compressed air
The water distribution circuit will include a mill solution tank fed by thickener overflow and a portion of water reclaimed from the TMF. Mill solution water contains cyanide and is used in the grinding circuit to form slurry and adjust percent solids. The remainder of reclaimed water goes to a reclaim water tank, used as wash water on screens and transferred to the carbon water tank for carbon transfer during acid wash and elution. Mine water is collected in the mine water tank and used for reagent preparation and slurry pump gland sealing. Water system capacity is reviewed to meet higher throughput requirements. The existing air compressor will supply air to the new leach tanks.
Key reported parameters
| Parameter | Unit | Initial (800 tpd) | Expansion Phase 1 (1,200 tpd) | Basis |
|---|---|---|---|---|
| Plant Feed Rate (Nominal) | tpa | 276,000 | 420,000 | E (Process calculations) |
| Plant Feed Rate (Barry) | tpd | 800 | 1,200 | A (Owner) |
| Operating Schedule | d/yr | 345 | 350 | A |
| Operating Hours, Concentrator | hr/d | 24 | 24 | A |
| Operating Hours, Crushing Plant | hr/d | 8 | 12 | A |
| Availability, Concentrator | % | 92 | 96 | B (Standard industry practice) |
| Availability, Crushing Plant | % | 33 | 50 | A |
| Average Gold Grade | g/t | 5 | 5 | A |
| Gold Recovery | % | 95 | 95 | C (Soutex recommendation) |
| Crushing Solids Feed Rate | tph | 100 | 100 | E |
| Rod Mill Installed Power | hp | 400 | 400 | Existing equipment |
| Secondary Mill Installed Power | hp | 535 (1 unit) | 535 × 2 units | E |
| Secondary Mill Product Size P80 | µm | 75 | 75 | A |
| Cyclone Diameter | mm | 381 | 381 | C |
| Cyclones in Operation | unit | 2 | 3 | C |
| Pre-Leach Thickener Diameter | m | 12.2 | 12.2 | A |
| Thickener Underflow Solids | % w/w | 50 | 50 | B |
| Leach Residence Time | h | 12.3 | 8.2 | E |
| CIL Residence Time | h | 4.1 | 2.7 | E |
| CIP Residence Time | h | 12.8 | 8.5 | E |
| Total Leach, CIL, CIP Residence Time | h | 29.2 | 19.5 | E |
| Oxygen Concentration | ppm | 8 | 8 | C |
| Cyanide Concentration (NaCN) | ppm | 500 | 500 | C |
| Stripping Process | , | Pressure Zadra | Pressure Zadra | A |
| Stripping Mass | t | 3 | 3 | A |
| Elution Frequency | nb/d | 0.5 | 0.5 | A |
| Cyanide Dosage (NaCN) | kg/t | 0.6 | 0.6 | E |
| Hydrated Lime Dosage (CaO) | kg/t | 1.15 | 1.15 | E |
| Total Operating Cost | C$/t feed | 23.29 | 19.07 | , |
| Total Annual Operating Cost | C$ M/year | 6.30 | 8.01 | , |
Note: Source codes are A (criteria provided by owner), B (standard industry practice), C (Soutex recommendation), E (criteria from process calculations), and L (existing equipment specifications/process data). At initial throughput, total residence time includes 12.3 hours leaching, 4.1 hours CIL, and 12.8 hours CIP. At expansion throughput, residence times are 8.2 hours leaching, 2.7 hours CIL, and 8.5 hours CIP.
Technical qualifications
The report presents the 800 tpd configuration as existing equipment and historical operating capacity. The 1,200 tpd configuration is a proposed design for expansion, with design criteria from the sources indicated in the tables. Specific limitations and design bases noted in the report include:
- The expansion flowsheet was developed to use existing equipment and building space as much as possible.
- The rod mill is stated as capable of handling 1,200 tpd, but this is presented as a design assessment rather than demonstrated operating data.
- The total leaching time of 20 hours (including CIP) is described as “recommended” and considered sufficient for Barry material.
- Static screen design will be based on custom-made models already in use in other gold mills, rather than site operating data.
- Flocculant batch frequency is marked with source code G (assumed data).
- Ambient temperature, outdoor temperature, and relative humidity are owner-provided criteria.
- The existing crushing equipment is described with a daily 8-hour operating time for 800 tpd; reaching 1,200 tpd requires increasing to 12 operating hours per day, and crushing plant availability changes from 33% to 50%.
- The report states the current plant can process 800 tpd of Barry material without modifications, but the 1,200 tpd throughput requires specific modifications including additional grinding capacity, thickener feedwell retrofit, additional carbon handling equipment in the first leach tank, slurry pump changes, and a new induction furnace.
- The qualified person recommends the new electric induction smelting furnace; this is a recommendation rather than an installed item.
- Operating costs are presented for both throughput cases and are based on the process design criteria and flowsheet data in the report.
Source: Barry Open Pit Project, NI 43-101 Technical Report, July 25, 2022, Section 17.0 Recovery Methods.
Consolidated report summaries
The following former standalone pages about this operation were consolidated here on October 25, 2026. They are retained for source traceability; dates and figures reflect each report’s own effective date and may be superseded by the current information above.
Barry Gold Project — 2016 Preliminary Economic Assessment
This Preliminary Economic Assessment examines modifying the existing Bachelor mill from 750 tpd to 1200 tpd to process mineralized material from the Barry deposit.
Report context
The report was prepared in accordance with Canadian National Instrument 43-101, following discussions between Metanor and GoldMinds and a March 4th proposal for a Preliminary Economic Assessment (PEA) for mining and milling approximately 1200 to 1300 tonnes per day of mineralized material from the Barry deposit. The processing section was written by Gilbert Rousseau Eng. and describes the present Bachelor mill operation along with proposed changes to process the Barry material.
Processing route
Present milling operation
Metanor currently mines and mills approximately 750 tpd of Bachelor mine ore. The mill circuit comprises a 24” x 36” KueKen jaw crusher followed by a 4¼’ Simons standard cone crusher and then a 5½’ Simons short head cone crusher. Material crushed and screened to 3/8” is stored in a 1200 tonne fine ore bin.
From the fine ore bin, material is ground in a conventional grinding circuit comprising a primary 10’ x 14’, 400 HP rod mill followed by a 10½’ x 9’ x 10’, 525 HP tricone ball mill in parallel with two secondary ball mills: a 6’ x 10’, 150 HP mill and a 5’ x 10’, 100 HP mill. Feed F80 is 9,525 microns and final grind P80 is 75 μm. Classification is by a set of four 15-inch cyclones.
Cyclone overflow reports to a wood chips screen prior to gravity flow into a 40-foot single tray thickener. Thickener underflow is pumped to a bank of four 22’ x 22’ leaching tanks followed by four 22’ x 22’ CIP reservoirs, providing total leaching time of approximately 50 hours. Tanks are interconnected with launders allowing slurry to flow by gravity. Each tank has impeller mechanical agitators. Oxygen for leaching is provided by air sparging through the bottom of the agitator shaft. Adsorption tanks each have a woven wire inter-tank screen to retain carbon, with bypass facilities for maintenance.
Sodium cyanide solution is metered into the leach feed distribution box. Compressed air is distributed and sparged down agitator shafts to maintain a high dissolved oxygen profile. Fresh and regenerated carbon are returned to the circuit at CIP tank 4 and advance counter-current to slurry flow by pumping from tank 4 to tank 3 to tank 2, and so on. Loaded carbon is recovered from CIP tank No 1 using an air lift to a loaded carbon recovery screen. Leached tails pass through a safety screen before being pumped to the tailings pond.
The carbon elution and refining circuit comprises a loaded carbon tank, acid wash tank, carbon strip vessel, bank of electrowinning cells, and two Wabi type gold bullion furnaces. Stripped carbon is reactivated in a horizontal kiln, quenched, and classified. Classifier oversize is reused while very fine carbon particles are filtered and kept aside for shipment to a copper-gold smelter.
Tailings from the safety screen and other waste streams are combined in a tailings collection pump box and pumped to the tailings pond to settle. Supernatant water flows by gravity to a polishing pond, and clear water is pumped back to the process water reservoir.
Proposed changes for Barry mineralized material
The flowsheet will remain essentially the same with the following modifications. A new 90 tonne hopper and a 12” x 12” grizzly will be installed above the outside feeder to accept incoming material from the Barry deposit. Material will be brought to the ore hopper with the existing front end loader, and large chunks not passing the grizzly will be broken with a stationary hydraulic rock breaker.
The two small 150 HP and 100 HP ball mills will be removed and replaced with a single 500-550 HP ball mill to work in parallel with the existing tricone 525 HP mill.
Because of coarse gold particles within the Barry mineralized material, two new 40” Knelson concentrators (one in operation, one spare) and a shaking table will be added to the circuit at the grinding stage, prior to cyanide leaching.
Both 3 x 6 – 75 HP tricone mill discharge pumps will be replaced with two 6 x 6 x 15” SRL pumps with 100 HP motors.
To obtain approximately 40+ hours retention time in the leaching and CIP circuit, three new 30’ x 30’ tanks will be added.
The fine ore bin will be isolated from the main mill building to prevent heating of frozen material during winter and avoid condensation, ensuring free rock flow. The mill compressed air system is considered sufficient to aerate the new leaching tanks.
Anticipated gold recovery
Based on previous metallurgical testing, it is anticipated that 24% of the gold will be recovered at the gravity circuit. Out of the remaining 76%, another 71% will be recovered from leaching of the gravity tailings, for a total gold recovery of 95%.
Mill operation costs (OPEX)
Mill operating costs are for processing approximately 420,000 tonnes per year of Barry mineralized material. Cost estimation limits start at ROM storage and end at the polishing pond. Milling costs are based on salaries, consumption of reagents and other consumables, supplies, and power. Manpower costs include 35% fringe benefits and contingency allowances. Mill operation costs are considered to have an accuracy range of +/-35%.
Total mill operation cost is CAD $19.90 per tonne milled, comprising consumables and spare parts at $9.00, electric power at $3.18, salaries at $5.91, and miscellaneous at $1.81.
The mill workforce will remain essentially the same as August 2016 except for the addition of four loader operators and yard men, and two Knelson concentrator and table operators. Salaries include vacations and are based on 2,080 working hours per year. Total annual salaries including 35% fringe benefits and 10% overtime are CAD $2,483,271.65.
Consumables include electric power ($3.18/t), grinding media for rod mill ($1.00/t), grinding media for ball mills ($1.22/t), lime ($0.42/t), cyanide ($3.74/t), spare parts ($1.50/t), and other items at approximately 10% of the above ($1.11/t), for a total of $12.17 per tonne.
Capital expenditure (CAPEX)
Capital cost to increase Bachelor mill capacity from 800 tpd to 1200 tpd is estimated at CAD $1.1 million and is considered at a conceptual level with +/-30% accuracy. Major costs include: rock breaker ($110,000), shop-fabricated grizzly ($25,000), 90-tonne hopper and ramp ($50,000), two Knelson concentrators ($400,000), shaking table ($40,000), two tricone mill discharge pumps ($40,000), three leaching tanks ($300,000), isolation of fine ore bin ($20,000), and other costs at 10% ($100,000).
Key reported parameters
| Parameter | Value | Basis |
|---|---|---|
| Current mill throughput | 750 tpd | Historical operating data |
| Proposed mill throughput | 1200 tpd | Proposed design |
| Annual throughput (proposed) | 420,000 tonnes | Proposed design |
| Feed F80 | 9,525 microns | Historical operating data |
| Final grind P80 | 75 μm | Historical operating data |
| Crushed product size | 3/8” | Historical operating data |
| Total leaching time (current) | ~50 hours | Historical operating data |
| Target leaching time (proposed) | ~40+ hours | Proposed design |
| Gold recovery – gravity | 24% | Testwork (Chapter 13) |
| Gold recovery – leaching of gravity tails | 71% | Testwork (Chapter 13) |
| Total gold recovery | 95% | Testwork (Chapter 13) |
| Mill OPEX | $19.90 CAD/t | Estimate, +/-35% accuracy |
| Mill CAPEX | $1,085,000 CAD | Conceptual estimate, +/-30% accuracy |
| Primary grinding | 10’ x 14’, 400 HP rod mill | Historical operating data |
| Secondary grinding (current) | 10½’ x 9’ x 10’, 525 HP tricone ball mill; 6’ x 10’, 150 HP ball mill; 5’ x 10’, 100 HP ball mill | Historical operating data |
| Secondary grinding (proposed) | Existing 525 HP tricone ball mill in parallel with new 500-550 HP ball mill | Proposed design |
| Cyclone classification | 4 x 15-inch cyclones | Historical operating data |
| Leach/CIP tanks (current) | 4 leach + 4 CIP, 22’ x 22’ each | Historical operating data |
| Additional leach tanks (proposed) | 3 x 30’ x 30’ | Proposed design |
| Gravity concentration (proposed) | Two 40” Knelson concentrators + shaking table | Proposed design |
| Thickener | 40-foot single tray | Historical operating data |
| Fine ore bin capacity | 1,200 tonnes | Historical operating data |
Technical qualifications
Mill operating costs are considered to have an accuracy range of +/-35%. Capital cost estimates are at a conceptual level with +/-30% accuracy. The report notes that the idea of removing the two small ball mills and adding a single 500-550 HP ball mill, along with adding gravity concentration ahead of cyanidation, was at the suggestion of Goldminds. Anticipated gold recovery is based on previous metallurgical testing referenced in Chapter 13 of the report. The mill workforce projections are based on the August 2016 staffing levels with additions for Barry material processing.
Source: Technical Report – Preliminary Economic Assessment, Barry Gold Project, Quebec, Canada, Sections 17.1 through 17.7, GoldMinds Geoservices Inc.
