Invention Description
Clay-rich sediments can host significant lithium, including lithium adsorbed on mineral surfaces. Existing Li-extraction approaches for clay-based lithium deposits include roasting, acid leaching, and electrochemical processes; complete mineral destruction using acids and heating can mix lithium from surface, interlayer, and structural sites. This mixing can limit interpretation of lithium-isotope compositions, because structurally bound lithium and adsorbed lithium can record different fluid histories. A method that removes adsorbed lithium without destroying the clay structure could reduce reliance on costly acid processing for that lithium fraction and support better resolved analysis of lithium reservoirs in clay deposits.
Researchers at Arizona State University have developed a novel approach for extracting ore-grade quantities of adsorbed lithium from clay mineral surfaces or fluids/brines. Utilizing certain polyols (e.g., sorbitol and its isomer mannitol), natural biomolecules that complex with alkali metals, this method selectively removes lithium associated with interlayer and exterior clay-mineral surfaces while leaving lithium structurally bound in octahedral layers available for subsequent isotopic analysis. In tests with smectite containing ore-grade (2.2 wt.% Li) adsorbed lithium, the approach extracted more than 99% of the adsorbed lithium. This method supports lithium recovery from clay-rich deposits while also providing a framework to distinguish exterior, interlayer, and structurally bound lithium reservoirs for lithium-isotope studies.
This novel polyol extraction of Li from clay minerals selectively removes soluble and exchangeable lithium adsorbed on clay minerals while preserving structurally incorporated lithium.
Potential Applications
- Li-clay mining and processing operations
- Li brine processing
- Geochemical laboratories evaluating Li-clay deposits and Li isotope changes during clay mineral alteration
- Mineral exploration and ore characterization
Benefits and Advantages
- Leaves behind an organic molecule that is naturally decomposed in the environment, providing a beneficial source of carbon for microbes
- High adsorbed-Lithium recovery – more than 99%
- Biodegradable and environmentally benign alternative to conventional acid and heat treatments
- Selective Li reservoir separation –removes only surface adsorbed lithium (exterior and interlayer-Li), which can be ore grade amounts in expandable clays.
- Isotope-preserving – allows separation of Li reservoirs whose isotope ratios may reflect different fluid compositions and histories
- Applicable to both natural ore-grade and experimental clay samples
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