Island Gold District – NI 43-101 Technical Report

This report details the processing configuration for the Island Gold District, focusing on the existing and expanded Magino mill that will process ore from both the Island Gold and Magino operations.

Report context

The Island Gold District NI 43-101 Technical Report, dated August 6, 2025, presents the processing approach for the combined operations. During H1-2025, both the Island Gold and Magino mills processed ore from their respective operations. In July 2025, the Island Gold mill was placed into care-and-maintenance mode, with the Magino mill becoming the sole processing facility. Due to the limited use of the Island Gold mill relative to the life-of-mine plan, the report presents only the Magino mill process in detail.

Processing route

Step 1 Overview

The existing Magino processing facility began blending and processing Island Gold ore and Magino ore together in July 2025. In 2025 and 2026, Island Gold ore is pre-crushed at the existing Island Gold crushing plant and hauled to Magino via an approximate 2.7 km dedicated haul road at an initial rate of 1,200 tpd, increasing to 1,400 tpd by the end of 2025. Magino ore fluctuates between 9,800 and 10,000 tpd, resulting in a combined Step 1 mill throughput of 11,200 tpd through the Magino processing facility. Starting in 2027, Island Gold ore will be crushed underground and transported 6.6 km from the shaft complex to the Magino mill for processing.

The mill feed head grade is based on a 9:1 blend ratio of Magino lower-grade ore at a nominal 1.0 g/t gold and Island Gold higher-grade ore at a nominal 10 g/t gold, on average, producing an average feed grade of approximately 1.9 g/t gold. The overall gold recovery from the blend is expected to be approximately 96.0%.

Crushing and Blending

The existing crushing circuit at Magino consists of a primary jaw crusher, sizing screens, secondary cone crusher and associated material handling equipment. Magino ROM ore has a nominal top size of 1000 mm and is crushed at a rate of 10,000 tpd producing a product size of 42 mm. Komatsu HD1500 139 t haul trucks bring ROM ore from the open pit mining operations to the crushing plant.

The blending process uses a 9:1 ratio of Magino ROM ore and Island Gold pre-crushed ore. The Island Gold blending sequence consists of ore direct dumping every second truck on dayshift and stockpiling every other truck for night shift, blending with a Komatsu WA900 FEL.

Ore is dumped by haul truck and/or FEL into the primary crusher ROM bin and withdrawn by an apron feeder, passing over a vibrating grizzly with 100 mm spaced bar openings before feeding the jaw crusher. The jaw crusher is a Metso C-150 with a 220 kW motor, capable of processing 650 tph at a close-size-setting of 125 mm at a 67% utilization factor. The jaw crusher discharge product is conveyed to a 1.8 m x 6.1 m secondary crusher scalping screen with 60 mm apertures on the top deck and 35 mm apertures on the bottom deck. The scalping screen removes 30% of the jaw crusher product to the undersize.

The secondary crusher is a Metso HP 500 cone crusher with a 370 kW motor, capable of processing 550 tph at 67% utilization factor. Cone crusher discharge is collected on the stockpile feed conveyor where the combined feed of 630 tph is dumped into a 30,000 t fine ore storage fabric tent building. Material is reclaimed by two 7,800 mm x 1,200 mm apron feeders at a controlled rate to meet SAG mill feed requirements.

Grinding and Gravity Circuit

The SAG mill is 7.92 m in diameter with an effective grinding length of 4.42 m and a 5 MW variable speed drive. The ball mill is 6.10 m in diameter with an effective grinding length of 8.84 m and a 6.3 MW drive. Both mills, supplied by FLS, are equipped with squirrel cage induction motors. A common variable speed drive starts the ball mill first, then starts and operates the SAG mill in variable speed mode. The Step 1 grinding circuit processes 11,200 tpd and produces a primary grind size P80 of 75 µm.

Water is added to the SAG mill feed to maintain slurry density at 75% solids. SAG mill product passes over a 2,000 mm diameter x 2,400 mm trommel discharge screen with openings of 12 x 50 mm, with oversize conveyed back to the SAG mill feed conveyor. The trommel screen undersize flows to the cyclone feed pump box where it is combined with ball mill discharge product. The ball mill operates in closed circuit with ten classifying cyclones (8 operating + 2 standby). Cyclone overflow passes over a vibrating trash removal screen before gravitating to the 23 m diameter pre-leach thickener.

The gravity circuit utilizes two FLS Knelson concentrators, recovering approximately 40% of the gold from the mill feed. A slurry side stream is pumped off the ball mill discharge pump box to a 2.1 m x 4.8 m gravity feed scalping screen fitted with 2 mm x 13.5 mm slotted polyurethane panels. The undersize is divided between two FLS Knelson KC-QS40 centrifugal gravity concentrators operating on a batch basis. Gravity concentrate flows to a Consep Acacia Model CS3000 intensive leaching reactor (ILR), where it is deslimed and leached with NaCN, caustic and LeachAid™ at 40 °C. The leached residue is washed and returned to the grinding circuit.

Pre-Leach Thickening

The slurry product from the grinding circuit cyclone overflow trash screen flows to a 23 m diameter thickener unit where flocculant is added to produce an underflow density of 55% solids. The underflow is pumped using an 8 x 6 inch slurry pump to a series of five leach tanks. Clear thickener overflow water returns to the process water tank for distribution, primarily to the grinding circuit.

Leach and Carbon-in-Pulp

During Step 1, thickener underflow slurry is pumped to five agitated 3,300 m³ leach tanks with 90 kW dual impeller agitators in series and leached with cyanide under alkaline conditions. Overall leach residence time is approximately 27 hours depending on throughput. Approximately 40% of gold is recovered in the gravity circuit while the leach/CIP circuit recovers 94% of the remaining gold, resulting in an overall gold recovery of approximately 96%.

Vaporized liquid oxygen is added to the first three CIL tanks to improve leach kinetics. Slaked lime slurry is added to the leach feed distribution box to maintain slurry pH between 10.5 and 11.0. Cyanide solution is added to achieve the required concentration, maintained at or above 150 mg/L free cyanide throughout the leach circuit.

The Step 1 circuit uses a 7 x 150 m³ Kemix Pumpcell carousel CIP circuit. In a carousel circuit, carbon is not transferred from tank to tank; rather, the feed is progressively moved through a distribution launder. Each Pumpcell has a single inter-stage screen/agitator to retain carbon particles, providing approximately 1.1 hours of total retention time for gold adsorption. The slurry tailings stream flows by gravity to a carbon safety screen before transfer to the cyanide detoxification circuit.

Acid Wash and Elution

Loaded carbon slurry is pumped to a loaded carbon recovery screen, with loaded carbon reporting to a 4 t acid wash column. Prior to carbon stripping, loaded carbon is treated with a 3% hydrochloric acid (HCL) solution to remove calcium, magnesium and other salt deposits. The carbon is soaked in acid for 30 minutes, after which the spent acid is rinsed and discarded to the tailings pump box.

The existing AARL elution sequence begins with a pre-soak cycle using 2.5% w/w sodium hydroxide (NaOH) and 2% w/w NaCN solution. The pre-soak period commences once the prescribed volume is added, with the caustic/cyanide solution circulated through the column until a temperature of 95 °C is achieved. Elution water is then pumped through at two bed volumes per hour, with the temperature raised to 120 °C using a propane fired solution heater. Gold is stripped off the loaded carbon, with the eluate flowing up and out of the top of the column through the recovery heat exchanger to the pregnant eluate tank.

Carbon Regeneration

Carbon reactivation uses a propane fired rotary kiln. Dewatered barren carbon from the stripping circuit is metered into the reactivation kiln where it is heated to 650-750 °C in an atmosphere of superheated steam. Carbon discharges into a 2 t capacity quench tank and is screened to remove carbon fines. Reactivated carbon is returned to the CIP circuit via an 8 t regenerated carbon tank.

Reagents

Reagent systems required for the process include: CaO, flocculant, NaCN, HCl acid, NaOH, CuSO₄, and liquid SO₂.

SO₂ is delivered as a liquid in bulk tankers and transferred to bulk storage, with a vendor supplied vaporizer package converting the liquid to SO₂ gas. Bulk liquid oxygen is delivered in tankers and converted to gaseous oxygen, metered to the leach circuit and cyanide detox circuit. CuSO₄ is delivered in 1 t bulk bags and mixed with raw water to make a 15% solution. NaOH is delivered as a 50% concentration bulk liquid in 36 t tankers, stored in an insulated 42 m³ tank, and metered to the elution circuit. NaCN is delivered as a 30% liquid in 30 t tankers into two 80 m³ storage and distribution tanks, added to the leach feed and additional top up points in leach tank #3.

CaO is delivered in 40 t tankers and pneumatically conveyed to a 75 t storage silo. The CaO is extracted and fed into a slaking Verti-mill with process water to make a slurry. Hydrated lime is stored in a distribution storage tank and pumped into grinding, leach and detoxification circuits via a ring main.

Flocculant is delivered in 1 t tote bulk bags, with a vendor supplied mixing and dosing system. Flocculant solution at 0.5% w/v is aged before transfer to the flocculant storage tank, and diluted to 0.05% w/v at the point of use.

HCl acid is delivered in bulk by 30 t tanker trucks and transferred to a bulk storage tank fitted with a vent and scrubber, metered to the elution circuit as required.

Step 2 Expansion

The Step 2 expansion phase will utilize underground crushing of Island Gold ore along with existing Magino ore processed through the existing Magino crushing plant. Grinding will include the addition of a pebble crusher and auxiliary mill to re-crush the oversize product. The ball mill will be retrofitted with a new gear reducer to speed up to 78% of critical speed, improving mill throughput to 12,400 tpd. The Step 2 expansion is expected to be completed in Q3-2026, linked to the completion of the Island Gold underground shaft and ore handling system scheduled for completion between Q3-2026 and H1-2027.

The Step 2 blending will consist of 2,400 tpd Island Gold ore and 10,000 tpd Magino ore, producing an average feed grade of approximately 2.7 g/t gold. The overall gold recovery is expected to be approximately 96.0%.

An underground crushing system will produce a 125 mm crushed product, with ore skipped to surface and loaded into 40 t haul trucks (three Komatsu HM400 and two Western Star 40 t) for transport to the Magino crusher via a 6.6 km haul road.

Step 2 additions include:

• Installation of a pebble crusher and auxiliary mill to the existing grinding circuit
• Conversion of one existing leach tank into a pre-oxidation tank
• Installation of a leach feed transfer pump to split feed between existing and Step 2 leach circuits
• Installation of four additional leach tanks, providing approximately 48 hours additional residence time
• Installation of an additional CIL carousel circuit (8 x 150 m³ Kemix Pumpcell)
• Installation of an additional 6.0 t adsorption-desorption-recovery (ADR) plant
• Replacement of the existing gold room with a new gold room
• Installation of an additional cyanide destruction circuit
• Installation of a new tailings pumping system

In Step 2, the existing #1 leach tank will be converted to a pre-oxidation tank where only oxygen is added prior to cyanidation. Leach feed slurry is split, with two thirds pumped to the Step 2 leach feed distribution box while the remaining slurry gravitates through the four existing leach tanks. Total residence time between the two streams is expected to be 48 hours.

The Step 2 carbon elution will use the modified Pressure-Zadra elution system. Loaded carbon will be screened through a loaded carbon screen prior to a 6 t acid wash vessel, using diluted 3.0% w/v nitric acid. The Pressure-Zadra process will use a 1% w/v NaOH solution and 0.2% w/v NaCN solution, pre-heated to 95 °C. The barren elution solution is redirected to the bottom of the 6 t pressure vessel, with temperature and pressure increased to 140 °C and 350 kPa.

Step 2 Electrowinning and Gold Room

In Step 2, pregnant eluate is pumped through two electrowinning cells with stainless steel mesh cathodes. Gold and

Key reported parameters

Technical qualifications

The source describes the recovery design; unreported operating results are not inferred.