Monday, 28 July, 2025/ Edition 69

In this edition of Core Elements, we will first look at lithium resources in Utah’s Great Salt Lake and then review advances in some technologies of direct lithium extraction from brine.

Rasoul Sorkhabi

Editor, Core Elements

Lithium Resources in Great Salt Lake

Great Salt Lake, Utah/Utah Geological Survey

Utah Geological Survey has published a report on estimates of lithium, magnesium, and potassium resources in Great Salt Lake brine.

Study Design:

• The Report uses data collected by the Utah Geological Survey from 1966 to the present.

• The data comes from eight sampling sites in Great Salt Lake.

• For lithium, there is a data gap between 1999 to 2018.

Resources:

• The study estimates that the in-place lithium resource in Great Salt Lake brine, based on recent sampling, range from 360,000 to 460,000 metric tons, averaging about 410,000 metric tons. This estimate is comparable with Compass Minerals’ estimate of 438,000 metric tons in 2023.

• The estimate of in-place resources for magnesium is 91 million metric tons and for potassium is 57 million metric tons since 2011.

• The resources of magnesium and potassium do not show significant change since 2000, suggesting that these may be recharging.

Concentrations:

• Lithium concentrations range from 3 to 52 milligram per liter.

• Magnesium concentrations range from 1.1 to 14 g per liter.

• Potassium concentrations range from 1.0 to 9.5 gram per liter.

Note: One gram per liter is about 1000 parts per million.

Production Status:

• US Magnesium has produced magnesium metal and Compass Minerals has produced magnesium chloride from the region.

• Compass Minerals produces potassium sulfate.

• US Magnesium produced lithium as a byproduct and Compass Minerals had plans to produce lithium, but those plans are idle for commercial reasons.

The bottomline:

• Increasing interest in lithium production from saline lake brine has motivated new studies of lake brine in several states in the USA.

• Utah and Nevada offer great potential for production of lithium from lake brine.

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Advances in Membrane Technologies in Lithium Extraction

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Two articles in Separation and Purification Technology and Advanced Membranes discuss new developments in membrane methods to extract lithium from salt-lake brine.

Context: Lithium extraction methods from brine fall under two categories:

1. Evaporation method involves evaporation of brine in a large-scale open pond. This method wastes water resources, has large footprints, and takes many months. Native peoples in South America’s Lithium Triangle have complained about the evaporation mining on their lands.

2. Direct Lithium Extraction (DLE) methods involve various technologies to separate lithium from co-existing metals (especially magnesium) and organic matter in brine using physical and chemical principles.  

DLE Methods: There are currently five DLE methods:

1. Adsorption utilizes specific adsorbents to selectively capture lithium from brine.

2. Precipitation is one of the earliest methods and involves the addition of participants (such as sodium carbonate or aluminum hydroxide) to induce the formation of lithium carbonate or lithium aluminate.

3. Solvent extraction is a separation technique that exploits the differential distribution of lithium between two immiscible liquids.

4. Electrochemical methods leverage processes like electrodialysis and capacitive deionization to selectively separate lithium ions.

5. Membrane methods use specialized membranes to selectively separate lithium ions from brine solutions.  

Each of the above five methods have their pros and cons.

New studies: Two new studies deal with membrane separation methods.

Study #1. Zhang et al. discuss the nanofiltration (NF) membrane for magnesium and lithium separation from brine.

• NF membranes are semi-permeable with nanometer pore sizes allowing for metal separation based on size and charge. The authors recommend NF membranes with negatively charged property with the biggest pore size no more than the hydration diameter of magnesium ions.

Study #2. Wang et al. discuss metal-organic framework (MOF) strategies for lithium extraction from brine.

• MOF membranes are made from crystalline solids with highly porous structures fabricated by connecting metal ions with organic substrates (mainly polymers). They have high specific surface areas and tunable pore structures. However, their long-term stability and reusability require further research and development.     

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A New Material for Lithium Adsorption

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Adsorption is one of the direct extraction methods of lithium from brine. However, lithium recovery by this method is very limited because of existing less efficient adsorption materials.

To resolve this limitation, much research is currently done on synthesizing efficient adsorption materials. A recent article by a group of Chinese scientists in Surfaces and Interfaces reports on a recyclable surface ion-imprinted graphene aerogel for high selective adsorption of lithium.

Graphen Aerogels:

• Also called graphene sponges, they are 3D macroscopic materials with porous network structures.

• They are made by the interconnection of 2D graphene nanosheets.

• They exhibit low density, high porosity, and extensive surface area for adsorption process.

New study:

• The researchers synthesized recyclable graphene-based surface ion-imprinted adsorption materials through liquid-phase self-assembly procedure.

• They used graphene oxide as the skeleton material and thiourea dioxide (thiox) as the reducing agent.

Testing: The new material demonstrated

• structural stability (bearing 10,000 times of its weight)

• high adsorption capacity (31.66 milligram per gram)

• high selectivity and regeneration performance (91 percent after six cycles)

Advantages: The new synthesized ion-imprinted adsorbent is more efficient than the previously tested materials including:

• Synthesized silica gel/graphene polymer with a maximum capacity for lithium of 1.1 milligram per gram reported by Ding et al.

• Polymeric nanoparticles with a saturated adsorption capacity of 7.07 milligram per gram reported by Hashemi et al.

Why it matters: Adsorption method is a relatively low cost, no pollution process. The new study offers new material for better recovery of lithium from brines.

Go deeper: Read the full article here.

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✉️ To get in touch with Rasoul, send an email to editorial@aapg.org.