CleanTech Lithium (AIM:CTL) has produced lithium carbonate of up to 99.75% purity from a pilot trial at its Laguna Verde project in Chile, validating the process flowsheet set out in the project's Pre-Feasibility Study (PFS).
The AIM and Frankfurt-listed exploration and development company said independent analysis by Alex Stewart Laboratory confirmed the purity levels, which clear the 99.5% threshold typically required for battery-grade material.
The PFS, completed in March, defined a maiden Probable Ore Reserve of 378,000 tonnes of lithium carbonate equivalent at Laguna Verde and set out plans for a 15,000 tonne-per-annum operation running for 25 years, with a pre-tax net present value of approximately $1.4 billion and an internal rate of return of approximately 24%.
The company engaged Lanshen, which developed the PFS process design, to run the optimisation trial, processing 24 cubic metres of feed brine through a pilot plant in Santiago that replicated all stages of the PFS design.
Key direct lithium extraction (DLE) parameters, including lithium adsorption yield and adsorption capacity, exceeded PFS design benchmarks, supporting the planned commercial-scale output based on ten carousels of 1,500 tonnes each.
A DuPont FilmTec LiNE-XD nanofiltration element outperformed the PFS baseline, achieving 99.8% magnesium rejection, 95.0% calcium rejection and lithium recovery of 98.3%, while an ion-exchange polishing stage cut calcium and magnesium levels to under 1 mg/L.
Multi-stage reverse osmosis combined with forced evaporation recovered and recycled more than 90% of desorption water back into the DLE stage, with zero salt precipitation during evaporation testing, addressing a key scaling risk.
"These are highly encouraging results for the Laguna Verde project," said Ignacio Mehech, chief executive of CleanTech Lithium.
"The pilot trial supports the PFS modelling under continuous pilot-scale operating conditions. This successful optimisation provides us with clear engineering improvements as we de-risk the project and move into our final design phase."
Three samples produced in the laboratory-scale carbonation stage returned lithium carbonate content of between 99.69% and 99.75%, with low concentrations of sodium, potassium, calcium and boron impurities.
The results feed into CleanTech Lithium's push toward a Definitive Feasibility Study for Laguna Verde, alongside its parallel efforts to secure ratification of the project's 40-year Special Lithium Operating Contract, still under final review by Chile's Comptroller General's Office, and to select a strategic partner to fund the project's next stage of development.