Technical Report on the James Bay Lithium Project — 2023

This report describes the planned mineral processing facility for the James Bay Lithium Project, including crushing, dense media separation, and tailings handling, as supported by testwork and design criteria.

Report context

This technical report was prepared in 2023 for the James Bay Lithium Project in Québec, Canada. It presents the designed processing route for upgrading lithium oxide contained in raw pegmatite feedstock into a spodumene concentrate. The design is supported by testwork that informs the current flowsheet and mass balance criteria.

Processing route

Run of mine pad

Run of mine ore is delivered by haul trucks from the pit to either direct tip into the crushing circuit or to a temporary stockpile on the ROM pad. A front-end loader reclaims material from the stockpile as needed. The pad is sized to allow truck circulation and temporary storage before feed enters the crusher ROM bin.

The in situ specific gravity of the ROM ore is 2.73, with a swell factor of 30%. The bulk density of the mineralized material is estimated at 1.75 t/m³. The stockpile height is limited to that required for storage capacity. A safety berm is installed around the top of the pad to prevent vehicles from falling and to segregate contact stormwater from clean runoff.

The ROM pad includes an impermeable layer and is graded at a minimum 2% downslope toward a sump area, allowing contact water to be pumped to the raw water pond for use in the process plant.

Three stage crushing circuit

Ore is passed through a 700 mm aperture grizzly into the ROM bin, with oversize broken down by a fixed rock breaker. Material is reclaimed from the ROM bin using a vibrating grizzly feeder with a 90 mm aperture. Oversize is reduced in a jaw crusher.

The jaw crusher product is fed over a double deck vibrating multislope sizing screen with top deck aperture of 38 mm and bottom deck aperture of 15 mm. Top deck oversize is conveyed to a secondary cone crusher; bottom deck oversize is conveyed to a tertiary cone crusher. Crushed material from both crushers is returned to the sizing screen feed. Undersize below 15 mm is conveyed to a covered crushed material stockpile.

The stockpile is enclosed by a 35 m high structural dome to prevent freezing during colder periods. Crushed ore is reclaimed by multiple vibrating pan feeders onto the DMS sizing screen feed conveyor located in a tunnel under the stockpile.

Dense media separation

Dense media separation uses a ferrosilicon slurry, known as correct medium, with a high specific gravity. The higher density medium enhances the floatability of lower density gangue material, while higher density valuable minerals sink.

Material from the crushing circuit is transferred to the DMS sizing screen feed box, where process water is added to form a slurry. The slurry is passed over a vibrating multislope sizing screen with a deck aperture of 1 mm.

Primary DMS

Oversize material (-15 +1 mm) is transferred into Primary DMS Mixing Boxes 1 and 2, where it is combined with FeSi correct medium. The -1 mm undersize is collected in a hopper and pumped to tailings dewatering cyclones.

Slurry from each mixing box is pumped separately into two groups of two 510 mm diameter cyclones arranged in parallel. The cyclones use centrifugal force to separate denser particles from lower density particles. Floats and sinks are processed through separate drain and rinse screening circuits, first through inclined static drain screens with 800 µm aperture, then through single deck vibrating screens with 800 µm aperture. Undersize from both drain sections is reused as correct medium.

Oversize from the sinks screen reports to a double deck vibrating sizing screen. Top deck oversize and bottom deck oversize are separated as coarse and fine material, both processed through separate secondary DMS stages.

Primary floats screen oversize is discharged as tailings via conveyors to the coarse tailings bin. FeSi is removed from screen oversize by water sprays and recovered from screen undersize by magnetic separation for recycling.

A bleed of correct medium containing heavier suspended particles is passed through a degrit sieve bend with 600 µm aperture. The undersize is reused as correct medium; the oversize is screened using a single deck high frequency vibrating screen with 600 µm aperture. Undersize is directed to the dilute medium circuit; oversize is combined with coarse tailings.

Secondary fine DMS

Fine -4+1 mm sinks material from the primary DMS circuit is mixed with additional FeSi correct medium before being fed into a 350 mm fine cyclone. Underflow material (sinks) from the cyclone is screened through an inclined static drain screen with 800 µm aperture, then a single deck horizontal vibrating screen with 800 µm aperture. Undersize is recycled as correct medium; oversize is conveyed to the final product stockpile.

Overflow material (floats) from the fine cyclone is screened through an identical circuit. The undersize is recycled as correct medium; the oversize is collected and processed as coarse tailings.

Medium recovery

FeSi is recovered from the secondary coarse DMS dilute medium circuit using a magnetic separator. The magnetic fraction is demagnetised in a demagnetising coil and reused as correct medium. Non-magnetic effluent is either processed as tailings or used to dilute correct medium to the appropriate concentration.

A bleed of correct medium from the recrush circuit and secondary fine circuit is fed into a degrit sieve bend with 600 µm aperture. Underflow is recycled as correct medium; overflow is screened through a single deck high frequency vibrating screen with 600 µm aperture. Undersize is directed to the dilute medium circuit; oversize is processed as tailings.

Tailings processing

Coarse tailings from various plant areas are fed onto the coarse tailings bin via a transfer conveyor and discharged into haulage trucks for transport to the tailings stack. Sources include primary coarse DMS floats, primary degrit screen oversize, secondary fine DMS/recrush floats, secondary coarse degrit screen oversize, and secondary fine/recrush degrit screen oversize.

Fines tailings are initially dewatered in two tails dewatering cyclones in duty/standby arrangement. Cyclone underflow reports to the fine tailings dewatering screen; cyclone overflow is fed to the tailings thickener feed box, where it is mixed with diluted flocculant and fed into a 13 m diameter thickener. Sources of fines tailings include DMS sizing screen undersize, DMS scavenger magnetic separator effluent, DMS dewatering cyclone overflow, material returned from spillage sumps, and recrush sizing screen undersize.

Thickener overflow is collected and reused as process water. Thickener underflow is approximately 60% wt/wt solids and is fed onto the fines tailings dewatering screen with the dewatering cyclone underflow. The dewatering screen produces oversize at approximately 19% moisture, with undersize recycled to the dewatering cyclone feed. Screen oversize is conveyed to the fines tailings bin for discharge into haulage trucks.

Reagents

Flocculant

Flocculant is used as an agglomerating medium in the tails processing area to separate water from solids. It is delivered to site in powdered form in 25 kg bags, mixed with raw water in a flocculant mixing tank, and homogenised to a solution concentration of about 0.25% w/v. The solution is stored in a flocculant storage tank and sent to the tailings thickener by dosing pumps via an in-line mixer.

Lime

Hydrated lime is delivered to site in 20 kg bags. During extended plant outages it is added as required to maintain a pH greater than 8.5 in the FeSi sumps to prevent corrosion. Nominally 2 kg of hydrated lime per tonne of FeSi is added, dependent on the initial pH of the FeSi slurry in the sump.

Ferrosilicon

Ferrosilicon powder is delivered to site in one ton or two ton bags, mixed with water in a FeSi make-up system to the required slurry solids concentration for transfer to the appropriate DMS correct medium tank.

Water systems

Raw water from a local supply is delivered into a raw/fire water tank equipped with a heater to prevent freezing during colder months. Water is discharged into two streams depending on downstream use: one feeds process water tanks, the other is sent to the raw water distribution line.

Water from the tailings thickener overflow is collected in one of two process water tanks and sent to the process water supply main. Water can be recycled back into process water tanks as required.

Raw water is filtered by one of two gland water filters and collected in the gland water tank, then pumped and distributed into the gland water ring main.

Key reported parameters

Technical qualifications

The process description is based on the planned design for the James Bay Lithium Project. Testwork supports the current design criteria including detailed mass balance and operating principles. The flowsheet is designed to produce spodumene concentrate at a grade of 5.6% Li₂O and at recoveries of 69.6% in early years and 66.9% in mid/later years.

Specific limitations in the report include:

• The recrush circuit description includes a cone crusher in closed circuit with a vibrating screen to produce material at 6.3 mm, but the overall recrush circuit configuration is not fully detailed.
• The secondary coarse DMS cyclone diameter is not reported; only the fine cyclone diameter of 350 mm is specified.
• No throughput rates, tonnage capacities, or equipment sizing details are provided for the crushing, screening, or DMS equipment.
• No water consumption or reagent consumption rates are provided beyond the nominal lime addition rate.
• No tailings storage facility details are provided beyond the coarse tailings bin and fines tailings dewatering system.
• The report notes a secondary fine DMS circuit but does not provide a corresponding subsection number for it in the original document structure.

Source: Technical Report on the James Bay Lithium Project, Québec, Canada, 2023, Section 17: Recovery Methods.