This section describes the proposed processing route for spodumene recovery from the Raleigh Lake lithium mineralisation zone, based on laboratory testwork and scoping-level engineering.
Report context
The recovery methods section of the 2024 NI 43-101 Technical Report (PEA) for the Raleigh Lake Project, dated January 18, 2024, focuses solely on the spodumene recovery process from the lithium mineralisation zone. The rubidium zone is not planned for development and is excluded from this section. Process design is based on SGS Lakefield laboratory testing results presented in Section 13 of the report, and engineering and design were developed to scoping level. Two feasibility studies were referenced for similar design criteria: the Rose Lithium Tantalum Project Feasibility Study (Critical Elements Lithium Corporation, July 2022) for crushing plant design, and the Grota Do Cirlo Lithium Project Technical Report (Sigma Lithium, June 2023) for DMS plant design.
Processing route
Process Design Basis
The proposed process plant is designed to crush 1,500 tonnes per day (tpd) and then process the same tonnage through a dense media separation (DMS) plant to produce a nominal 56,000 tonnes per year (tpy) of 6% Li₂O spodumene concentrate at 81% recovery. A design factor of 10% is applied on nominal requirements to account for expected feed variation. The plant design is based on testwork performed to date and knowledge acquired in processing spodumene mill feeds. The SGS laboratory testing obtained 22.9 weight percent of 6% lithium concentrate with an estimated 81% lithium recovery.
General Equipment Selection
The base case for the PEA is a standard three-stage 1,500 tpd crushing plant and a multi-stage 1,500 tpd DMS plant. At 81% recovery and at the life-of-mine head grade, the DMS plant is estimated to produce approximately 56,000 tpy of 6% Li₂O. Additional equipment to remove mica and magnetic iron has been included to improve spodumene concentrate quality.
Primary Jaw Crushing
The primary crushing building houses the mill feed hopper, stationary grizzly, rock breaker, vibrating grizzly feeder, and jaw crusher. Run-of-mine mill feed is hauled from the open pit mine and dumped directly into the mill feed hopper. A stationary grizzly on the hopper prevents oversized rocks from reporting to the jaw crusher, and a rock breaker breaks oversize boulders. A vibrating grizzly feeder (1.6 m wide by 6.1 m long) extracts mill feed from the hopper and feeds oversize to a 224 kW jaw crusher. Undersize material less than P80 of 150 mm bypasses the jaw crusher. Crushed mill feed and fines are conveyed to the secondary crushing building. A 15-tonne overhead crane is installed in the jaw crusher building for maintenance. A dust collector with various pickup points collects dust generated at conveyor discharges and transfer points.
Secondary and Tertiary Crushing
The crushed mill feed from the jaw crusher is screened on a secondary vibrating screen consisting of one 1.8 m wide by 4.80 m long double-deck screen with a top deck aperture of 100 mm and bottom deck aperture of 35 mm. Oversize from both decks is crushed in a secondary cone crusher of 300 kW, producing crushed mill feed at a P80 of 39 mm. The discharge from the secondary crusher and the screen undersize are sent to a tertiary double-deck vibrating screen, 2.4 m wide by 8.5 m long, with a top deck aperture of 32 mm and bottom deck aperture of 1 mm. The strong lithium beneficiation performance observed in the heavy liquid separation (HLS) testing indicated that crushing to minus 12.7 mm and screening to 1 mm, then using DMS, is a viable process flowsheet for producing 6% Li₂O spodumene concentrate at 81% recovery.
Key reported parameters
| Parameter | Nominal | Designed | Units |
|---|---|---|---|
| Plant Operating Schedule | |||
| Operating hours per day | 24 | 24 | h |
| Annual operating days | 365 | 365 | days/y |
| Shifts per day (Crushing and Wet Plant) | 3 x 8 | 3 x 8 | shifts x hrs |
| Equipment utilization – Crushing Plant | 68% | 68% | % |
| Equipment utilization – Wet (DMS) Plant | 85% | 85% | % |
| Plant Feed | |||
| Feed – Crushing Plant | 1,500 | 1,500 | tpd |
| Feed – Wet (DMS) Plant | 1,500 | 1,500 | tpd |
| Solids | 97% | 97% | % |
| Plant Product | |||
| Concentrate production | 56,000 | 56,000 | tpy |
| Concentrate recovery | 81% | 81% | % |
| Concentrate grade (Li₂O) | 6% | 6% | % |
Project website: https://www.nsenergybusiness.com/projects/raleigh-lake-project-canada/
Technical qualifications
The process plant design is based on testwork performed to date (Section 13 of the report) and knowledge acquired in processing spodumene mill feeds. Engineering and design were developed to a scoping level based on the results of SGS laboratory testing. A 10% design factor is applied on nominal requirements. The report states that the rubidium zone is currently not planned for development and is excluded from this section. No detailed flowsheet, material balance, equipment sizing, capital costs, or operating costs are presented in the provided evidence.
Source: Raleigh Lake Project , NI 43-101 Technical Report (PEA), January 18, 2024, Section 17 Recovery Methods.
