The Preliminary Economic Assessment for the Perron Project defines a two-phase processing approach, beginning with toll milling and transitioning to an on-site carbon-in-leach plant.
Report context
The NI 43-101 Technical Report and Preliminary Economic Assessment for the Perron Project, Quebec, Canada, is dated October 17, 2025. The report presents a processing strategy comprising Phase 1 toll milling at 1,000 tonnes per day and Phase 2 on-site CIL plant operation at 2,000 tonnes per day commencing in year 5. Metallurgical test work was conducted by SGS Canada Inc. in 2020 and 2024 for Amex Exploration; no new metallurgical testing was performed specifically for the Preliminary Economic Assessment.
Processing route
Phase 1 , Toll milling
Bumigeme has identified four toll treatment plants within a 200 km radius capable of processing at least 1,000 tpd of head feed. The plants are designated by letters A, B, C, and D; Bumigeme has not contacted the companies holding these plants. Expected gold recoveries for each plant are as follows: Plant A (SAG Mill, Ball Mill, Gravity and CIL) 95%; Plant B (Rod Mill, Ball Mill, Gravity and CIP) 94%; Plant C (Rod Mill, Ball Mill, Gravity and CIL) 95%; Plant D (SAG Mill, Ball Mill, Gravity and CIL/CIP) 95%. Based on test work on Perron mineralization and the treatment processes studied, Bumigeme projects an average recovery rate of 95.0% for the toll treatment operation. During Phase 1, mineralized material will be transported from the mine site to the toll milling facility by a contractor using on-highway trucks. Amex Exploration assumes sole responsibility for negotiations with the management of the toll treatment plants.
Phase 2 , On-site CIL plant
The proposed process plant design for Phase 2 is based on a standard metallurgical flowsheet to treat gold bearing material at a rate of 2,000 tpd to produce doré. The flowsheet is based on metallurgical test work, industry standards, and conventional unit operations. Mineralized material will be sourced from underground mining (88%) and open pits (12%).
Primary crushing
Mineralized material from underground will be transported by 42-tonne haul trucks and from open pit by 37-tonne trucks. Run-of-mine mineralized material can be dumped into a 60-tonne feed hopper or placed on a stockpile when the crusher is idle or for blending purposes. A static grizzly screen is installed atop the hopper to remove oversized material, and a fixed rock breaker is used to break down oversized rocks. A 36-inch by 48-inch jaw crusher is fed by a vibrating grizzly feeder with a capacity of over 300 tons per hour. The primary crushing circuit is designed to reduce material size from minus 457 mm to minus 150 mm. The crusher operates for 12 hours per day, five days per week, 52 weeks per year, with 70% availability. A dust collector, self-cleaning magnet, and metal detector on the conveyor system prevent metal objects from reaching the storage dome.
Crushed mineralized material storage
Crushed mineralized material is conveyed to a dome stockpile providing 4,000 tonnes of live storage, sufficient for 48 hours of uninterrupted milling capacity. Material is withdrawn via three belt feeders, each 600 mm wide by 2 m long, with a capacity of 50–150 metric tonnes per hour, discharging onto a conveyor belt that feeds the SAG Mill.
Grinding circuit
The grinding circuit consists of a SAG Mill operating in open circuit followed by a ball mill in closed circuit with a cluster of hydro-cyclones. The SAG Mill is fed with material sized to 100% passing 150 mm. The SAG Mill may be powered by a variable speed drive to adjust for variations in material hardness. The ball mill grinds the material to 80% passing 74 µm. No tests are available to support the installation of a pebble crusher. Key elements include an 800 kW SAG Mill (5.5 m diameter by 1.8 m length, Asiatic Supplier), a 2,200 kW ball mill (4.5 m diameter by 6.1 m length, Asiatic Supplier), a cyclone cluster, and a 15 m diameter high-rate pre-leach thickener. Slurry from the SAG Mill discharges through a trommel screen; oversized material is collected in a trash bin and undersized material flows to the ball mill pump box. The ball mill discharges through a trommel screen with oversized material again collected. Water is added to the ball mill pump box to adjust slurry density for the cyclones. Cyclone overflow at 45% solids flows by gravity to a trash screen to remove wood and plastic chips, then proceeds by gravity to the pre-leach thickener. Thickener overflow is recycled as process water; underflow at 50% solids is pumped to the oxygenation and cyanidation tanks.
Gravity circuit
A QS30 Knelson concentrator, installed in the grinding circuit, recovers free gold from the cyclone underflow stream. A portion of the cyclone feed is diverted to the gravity circuit. Prior to entering the concentrator, the stream passes over a vibrating screen removing material coarser than 2 mm, which is returned to the grinding circuit. Undersized material feeds the centrifugal concentrator. Concentrates are discharged into a storage hopper and processed through a 1-tonne capacity Acacia intensive leach reactor. Tailings from the concentrator are routed back to the cyclone feed pump box. Acacia tailings are subsequently pumped to the ball mill pump box. A dedicated electrowinning cell is designated for treatment of the gold-rich pregnant solution from the intensive cyanidation unit.
Cyanidation and carbon adsorption
The milled product is thickened in the pre-leach thickener before entering the CIL circuit. The hybrid CIL circuit consists of one pre-aeration tank, one leach tank, and six adsorption tanks, each 10 m in diameter by 12 m high. The thickener underflow is pumped to the pre-aeration tank where process air is sparged for sulfide oxidation and lime is added for pH adjustment. Slurry then moves to the leach tank and through six agitated CIL tanks in series. Leaching is conducted using sodium cyanide with pH maintained at 10.5–11 via lime addition. All CIL tanks are sparged with process air. Slurry flows through the circuit via inter-stage pump screens; gold-loaded carbon is transferred counter-current to the slurry flow. Total residence time is 40 hours at a pulp density of 50% solids.
Gold recovery circuit
Loaded carbon from the CIL circuit is transferred to the elution circuit utilizing a standard pressure Zadra process. Loaded carbon undergoes acid washing and elution. Stripped carbon is reactivated in the carbon regeneration circuit before being returned to the CIL circuit. The pregnant strip solution is directed to electrowinning where gold sludge is collected and sent to a furnace for recovery as doré bullion.
Cyanide destruction
CIL tailings at approximately 45% solids flow by gravity to a carbon safety screen. Oversize material (recovered carbon) is collected for potential return to the CIL circuit; undersize material is pumped to two cyanide destruction tanks, each 8 m in diameter and 10 m high, providing total residence time of 4.6 hours. Cyanide destruction uses the SO₂/air process. Tanks are equipped with oxygen injection points and agitators.
Tailings thickening and disposal
Detoxified tailings are pumped to a 15 m diameter high-rate thickener to increase slurry density to 62–64% solids before being discharged into four empty pits. It is estimated that 50–60% of the water sent to the pits could be recovered and pumped back to the process water tank.
Reagent preparation and control systems
The plant is equipped with a reagent preparation and distribution system. Consumables include grinding balls (forged steel), pebble quicklime, hydrated lime, sodium cyanide, and flocculants. Processes are controlled by a SCADA automation system implemented through a redundant fiber optic PLC-based ring structure connecting all PLCs and E-Houses. Motor control centers feature Ethernet interfaces. The process plant building includes a laboratory, mill offices, a dry, and an electrical and mechanical shop.
Key reported parameters
| Parameter | Value | Unit | Basis |
|---|---|---|---|
| Phase 1 | |||
| Toll milling rate | 1,000 | tpd | Design |
| Expected gold recovery | 95.0 | % | Projected from testwork and plant flowsheets |
| Phase 2 | |||
| On-site CIL plant rate | 2,000 | tpd | Design |
| Average head feed grade | 4.27 | g/t | Design |
| Gold recovery (CIL) | 95 | % | Design estimate |
| Gold recovery by gravity | 35 | % | Design |
| Mill availability | 92 | % | Design |
| Milling rate | 90.6 | t/h | Design |
| Crushing rate | 334 | t/h | Design |
| Crushing size F80 | -457 | mm | Design |
| Crushing size P80 | -150 | mm | Design |
| SAG Mill power | 800 | kW | Design |
| Ball Mill power | 2,200 | kW | Design |
| Ball Mill grind size P80 | 74 | µm | Design |
| CIL retention time | 40 | h | Design |
| CIL pulp density | 50 | % | Design |
| Number of CIL tanks | 6 | Design | |
| Detoxification residence time | 4.6 | h | Design |
| Total electrical connected load | 5.1 | MW | Design |
| Operating demand load | 4.5 | MW | Design |
| Electricity consumption | 39.12 | kWh/t | Design |
| Total water requirement | 152.8 | m³/hr | Design |
| Fresh water requirement | 40.5 | m³/hr | Design |
| Recycled process water | 137.7 | m³/hr | Design |
| Testwork results | |||
| Gold recovery by gravity/cyanidation | Exceeding 95 | % | 2020 and 2024 SGS testwork |
Project website: https://www.amexexploration.com/properties/quebec-exploration-perron-property
Technical qualifications
Historical metallurgical test work was conducted by SGS Canada Inc. in 2020 and 2024 for Amex Exploration. No new metallurgical testing was performed specifically for the Preliminary Economic Assessment; all data relies on previous results detailed in Chapter 13. No tests are available to support the installation of a pebble crusher. Bumigeme has not contacted the companies holding the plants identified for toll treatment. Expected gold recoveries for toll treatment are based on review of each plant flowsheet and historical testwork, not on direct plant testing with Perron material.
Source: NI 43-101 Technical Report, Preliminary Economic Assessment, Perron Project, Quebec, Canada, October 17, 2025, Sections 1.17, 17.1–17.13.
