This technical report presents the proposed processing flowsheet, metallurgical testwork results, and design parameters for the production of technical spodumene concentrate from the Georgia Lake deposit.
Report context
This report section, dated within the Preliminary Economic Assessment, describes the recovery methods for the Georgia Lake lithium project. Metallurgical testwork was performed at the SGS Canada Inc. Testwork Facility in Ontario, comprising one locked-cycle test on the composite head sample, heavy liquid tests, and several flotation tests. The testwork results were used to derive the preliminary process flowsheet and provide design parameters for a processing facility on site. Provision is made for the storage of all process inputs and concentrate output to operate on a year-round basis.
Processing route
Overview
The suggested plant flowsheet, based on metallurgical tests carried out on three outcrop samples and one drill core sample from the Georgia Lake deposit, is subdivided into five sections: three-step crushing; gravity separation; milling; flotation; and dewatering of different products. The plant is designed for a feed capacity of 150 t/h or 1,000,000 tpa.
Crushing circuit
Material from the feed hopper is discharged to a 100 mm screen. Pre-screened feed material is crushed with a jaw crusher down to <100 mm. This crusher works in a circuit with a second 100 mm dry screen. The <100 mm material is fed to the middle and fine crushing steps, where it is crushed to <2 mm by roller crushers. The second roller crusher is a high pressure grinding rolls unit operating in closed circuit with the 2 mm wet screen. Tests are to be performed to confirm no significant negative impact on gravity separation or flotation.
Gravity separation section
Instead of heavy liquid separation used in testwork, gravity separation using spirals as the primary stage is proposed. Material minus 2 mm is fed to the pump sump box and transferred via slurry to hydro-cyclones for desliming. The cyclones overflow is directed to the thickener. Hydrocyclones could deslime the feed to spirals at approximately 63 µm or finer. The underflow of the cyclones is fed to spirals for gravity separation. Middling of the first step is fed to a second spiral step. The spiral section produces a final coarse spodumene concentrate and spiral tailings. Optionally, the final coarse spodumene concentrate is dewatered at a dewatering screen and stockpiled.
Milling section
Tailings from the gravity separation contain fine and unliberated spodumene and are transferred to the grinding section, fed via slurry pump to the ball mill 300 µm screens, which are in closed circuit with a ball mill. The underflow of the screens is directed to the mica flotation circuit.
Flotation
Mica flotation: The grinding screens undersize is pumped to cyclones for desliming. The overflow of the cyclones is directed to the tailings thickener. The underflow is directed to a conditioner tank where slurry is mixed with amine collector and fuel oil. The conditioned slurry flows to mica rougher flotation, followed by mica scavenger flotation. Rougher and scavenger concentrates are directed to a one-stage cleaner flotation. The mica final concentrate is pumped to a mica concentrate thickener or tailings thickener. Mica scavenger and cleaner tailings are directed to spodumene flotation.
Spodumene flotation: The first stage is high-density scrubbing in alkaline conditions to clean and activate particle surfaces. The scrubbed slurry is diluted and fed to desliming cyclones, with overflow directed to tailings thickener. Cyclone underflow is conditioned at neutral pH with spodumene collectors. The conditioned slurry flows to spodumene rougher flotation. Tailings of the spodumene scavenger flotation are directed to tailings thickener. Rougher and scavenger concentrates are directed to three or more stages of cleaner flotation. Tailings of the 1st, 2nd and 3rd cleaners are directed back to various flotation stages. The concentrate of the 3rd cleaner is directed to a magnetic separator for separation of magnetic concentrate and the final spodumene concentrate.
Dewatering section
All fine material from desliming cyclone overflows (with low floatable spodumene content), spodumene flotation tailings, and magnetic concentrate are combined in the tailings thickener feed. Thickener underflow is expected to be between 45 and 55% solids. This slurry is discharged to the tailings facility or pressure filtered to produce dry-stack tailings. Overflow of the tailings thickener may be used as process water in grinding and flotation circuits. For spodumene concentrate, vacuum filters are foreseen, with pressure filtration as an option to produce lower moisture content product. At this time a market for mica concentrate has not been identified.
Additional flowsheet considerations
Alternatively, screening at 2 mm is possible but should be performed wet. Wet recycle to high pressure grinding rolls could be substituted by wet primary grinding. HPGR could be inserted following tests followed by flotation. The +2 mm fraction could be sent to a ball mill. Desliming of the gravity feed may not be necessary if using spirals. The 2nd or 3rd stage of gravity can be a shaking table. Dense media separation could add undesirable amounts of iron from ferrosilicon and magnetite. Following grinding and desliming, there could be a high-percent-solids two-stage acid and amine conditioning step. Following mica flotation, there could be high pH scrubbing, desliming, and dense slurry conditioning with a spodumene collector. Decision is pending on whether tailings are thickened or thickened and filtered to dry-stack.
Key reported parameters
| Parameter | Value | Basis |
|---|---|---|
| Plant feed capacity | 150 t/h (1,000,000 tpa) | Design |
| Composite head sample Li₂O grade | 1.49% Li₂O (0.69% Li) | Testwork assay |
| Testwork recovery (constant) | Approx. 80% | Metallurgical testing |
| Technical concentrate grade | 6.2% Li₂O | Testwork |
| Recommended Li₂O feed for financial calculation | Below 0.90% Li₂O (0.42% Li) | Adaptation of SGS test results |
| Recommended Li₂O overall recovery for financial calculation | 78% | Adaptation of SGS test results |
| Thickener underflow solids | 45 to 55% | Design estimate |
| Desliming cyclone cut size | Approx. 63 µm or finer | Design parameter |
Project website: https://www.newswire.ca/news-releases/rock-tech-lithium-completes-pre-feasibility-study-for-its-georgia-lake-project-832189550.html
Project website: https://www.thenewswire.com/press-releases/1AqRFKnYP-arbor-metals-commences-phase-1-2026-drill-program-at-jarnet-lithium-project.html
Technical qualifications
The report notes that several issues remain to be considered in flowsheet selection. HPGR tests will be performed to confirm no significant negative impact on gravity separation or flotation. The metallurgical tests necessary for this report were carried out on a limited sample set of three outcrop samples and one drill core sample from the Georgia Lake deposit. The process descriptions provided in this section were based primarily on testwork and resulted in a preliminary flowsheet that served as the basis for the mill design model and a first CapEx estimate. Based on the outcomes of this PEA, progression to a Preliminary Feasibility Study is recommended, including development of engineering based on further metallurgical testwork.
Source: Recovery Methods section of the Georgia Lake Preliminary Economic Assessment technical report, pages 163-166.
