Neometals purifies lithium brines to optimise electrolysis

Battery materials recycler and chemicals producer Neometals says purification testwork on its pilot proprietary “ELi” lithium production process removes more than 97 per cent of brine feed-source impurities, creating a solution suitable for electrolysis.

The company says the level of purification in the clean brine solution meets the specification required for the electrolytic stage in its majority-owned and trademarked ELi process. Management says laboratory analyses show that more than 99.98 per cent of calcium, magnesium, boron and strontium and more than 97 per cent of silica was removed from the brine feed while using its process.

The purification testwork was undertaken by a third-party laboratory, with feedstock taken from a natural lithium brine salar in Argentina to represent actual site and source conditions.

The ELi process technology is owned by Reed Advanced Materials, which comprises a 70 per cent interest held by Neometals and the remaining 30 per cent interest is held by Mineral Resources.

In 2021, Reed revealed it had agreed on terms with Bondalti Chemicals, Portugal’s largest chlor-alkali chemical producer held by that country’s high-profile José de Mello Group, to evaluate the potential commercialisation of its ELi lithium process in Europe.

As part of the agreement, Bondalti and Reed would co-fund trials, construction and operation of a pilot plant at Estarreja in Portugal and complete evaluation studies over 18 months. The pilot plant and proposed commercial refinery would be integrated with Bondalti’s existing chlor-alkali operations, which share significant processing commonalities with the ELi process.

ELi replaces conventional, carbon-intensive chemical conversion of lithium chloride solutions with electrolysis to produce lithium chemicals, potentially using renewable energy. The full process comprises brine purification, followed by electrolysis where electricity is used to convert lithium chloride solutions into lithium hydroxide and/or lithium carbonate.

While many electrolytic processes have been trialed on brines, many have failed to perform due largely to contaminants.

Salar brines, whether from natural or man-made evaporative ponds or boreholes, have the potential to contain myriad impurities from multiple sources. They can include insoluble solids such as suspended windblown and run-off clays and sands and soluble and colloidal contaminants.

Additionally, occasional vertebrate residues – mostly from living and dead birds – and live invertebrates and their residues can be carried in by wind or water. The latter may even be microfauna, which inhabit the salar brine.

All this means that the first purification stage is vital for the subsequent pilot phase to work. The ELi process includes pre-filtration as the first step, followed by ultra-fine nano-filtration.

Neometals says its ELi process has several advantages over conventional systems, including lower operating expenditures through substitution of electricity for chemical reagents, higher product purity and a smaller carbon emissions footprint. It says its purification removes the impurities which disrupt electrolytic efficiency and hence increases consumption.

Additionally, higher and more stable electrical current flow extends the life of electrolytic membranes, reduces maintenance and increases the grade of the final product.

The company says that as the pilot testwork nears conclusion, Reed and Bondalti Group are continuing to co-fund the agreed pilot plant activities while a new cooperation agreement is being negotiated.

An engineering cost study envisages a plant throughput of 80,000 tonnes per year of brine containing 6 per cent lithium for a production of 25,000 tonnes per annum of lithium hydroxide monohydrate (LHM).

Neometals say full-scale testing is scheduled for Vancouver late this year and will be followed by a long-term pilot scale run and lithium hydroxide crystallisation in Buffalo in next year’s first quarter.

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