Seymour’s Simple DMS Flowsheet Reduces Processing Risks but Recovery Challenges Remain

Metallurgical Breakthrough at Seymour

Green Technology Metals Limited (ASX: GT1) has released compelling metallurgical testwork results from its flagship Seymour lithium project in Ontario, Canada. The latest variability and ore sorting test programs validate the production of a high-grade spodumene concentrate with lithium oxide (Li2O) content between 5.5% and 6.1%, coupled with impressively low iron oxide (Fe2O3) impurities below 1%. These outcomes align closely with previous testwork and benchmark well against leading global hard rock spodumene operations.

Central to the findings is the confirmation that a simple, dense media separation (DMS) processing circuit, eschewing more complex flotation steps, can reliably deliver spodumene concentrates at industry-standard recoveries. The DMS testwork yielded a spodumene concentrate grading 6.1% Li2O with 0.9% Fe2O3 and a lithium recovery rate of approximately 61.9% after magnetic separation, underscoring the robustness of the proposed flowsheet.

Ore Sorting Enhances Feed Quality and Reduces Dilution Risk

Complementing the DMS results, preliminary ore sorting trials conducted by Steinert US demonstrated effective segregation of lithium-bearing spodumene from waste rock. The tests showed mass rejection rates consistent with mine dilution estimates, with significant iron reduction, up to 80% in some composites, while maintaining lithium losses below 10%. This selective gangue removal capability offers a promising avenue to optimize feed grades and potentially adjust mine cut-off thresholds, thereby enhancing overall project economics.

Ore sorting’s ability to upgrade lower-grade and higher-iron feed materials could be integrated into the processing flowsheet as mine planning advances, providing operational flexibility and risk mitigation against feed variability.

Strategic Implications for Seymour’s Development

GT1’s Managing Director, Cameron Henry, highlighted that these metallurgical insights significantly de-risk the Seymour project’s development pathway. The confirmation of a straightforward, modular DMS plant design aligns with the company’s strategy to maintain capital discipline while achieving strong lithium recoveries and concentrate quality. The testwork also supports ongoing feasibility study efforts, which will incorporate these findings to refine plant design and cost estimates.

Additional testwork is underway, including further HLS and magnetic separation on DMS middlings, gravity separation for tantalum recovery from magnetic rejects, and thickening and filtration studies to finalize process equipment sizing. These efforts aim to unlock further value and optimize the processing circuit ahead of construction decisions.

Context Within GT1’s Broader Lithium Portfolio

The Seymour project forms a critical part of GT1’s vertically integrated lithium business in Ontario, which collectively holds a global mineral resource estimate of 24.9 million tonnes at 1.13% Li2O. The company’s assets benefit from excellent infrastructure, including clean hydroelectric power and rail access, enhancing the project's logistical and environmental profile.

GT1’s focus on hard rock spodumene deposits with scalable, low-complexity processing routes positions it well amid growing demand for battery-grade lithium feedstocks. The Seymour testwork results reinforce the project’s potential to contribute meaningfully to the lithium supply chain with competitive concentrate quality and recoveries.