Trends in Direct Lithium Extraction Technologies

Written by Bharat (Bob) Bhushan, Ph.D., and Purnima Singh, Ph.D., research scientists at Alpha Cleantech Labs Inc.

Lithium is a light and highly reactive metal. It is the principal component of one of the most promising forms of high-energy-density batteries. The demand for lithium will continue to increase due to the increased usage of rechargeable lithium-ion batteries (LIB) in electric vehicles, smartphones, and other electronic appliances. By 2025, demand is expected to reach 1.5 million tonnes of lithium carbonate equivalent (LCE) and by 2030, this number is estimated to exceed 3 million tonnes. Lithium is also a critical component for ceramics, glass, metallurgy, air treatment products, pharmaceuticals, and polymers. The natural sources of lithium are mainly in forms of water resources and ore bodies, such as spodumene, lepidolite, and petalite ores. Significant concentrations (a few hundred ppm) of lithium are found in geothermal waters across the world. Interestingly, brines (high saltwater bodies), represent a valuable resource for lithium due to the capacity of geothermal power plant to process very high volume of brine (>6000 gal per min). The grown interest in lithium extraction derived from water resources is attributed to the low cost, natural abundance of water bodies, and environmental friendliness of the extraction process. 

Geographical distribution of lithium around the world

In the 1990s, the United States (U.S.) was the largest producer of Lithium accounting for over one-third of global lithium production in 1995. From 2010, Chile took over as the largest producer of Lithium with a production boom in the Salar de Atacama, one of the world’s richest lithium brine deposits. Australia and Chile are currently the top producers of lithium, accounting for almost 77 per cent of the global production in 2022. Australia, the world’s leading producer, extracts lithium directly from hard rock mines, specifically the mineral spodumene. Chile, Argentina, China, and other top producers, extract lithium from brine. China currently holds a dominant position in the world’s lithium supply chain which is attributed to its nearly 60 per cent lithium refining capacity for batteries. Geographical distribution of World’s Lithium rich brine deposits is shown in Figure 1.       

The Canadian perspective 

The growing demand of electric vehicles in Canada has prompted exploration of lithium mining resources recently. Currently, Canada does not produce much lithium compared to other countries. Approximately 2.5 per cent of the world’s known lithium deposits have been reported across Canada. Recently there’s a growing interest in lithium mining across Canada as listed below: 

• Quebec has been reported as the centre for greatest number of active lithium projects in Canada due to its known historical production of lithium.
• The federal government has approved Galaxy Lithium (Canada) Inc. to build a new lithium mine in Quebec.
• Ford signed a deal to buy lithium for electric car batteries from Quebec’s Nemaska Lithium.
• Arbor Metals, a Vancouver based company is making progress with a lithium mining project in the James Bay region of Quebec.
• North American lithium producers, Sayona Mining, and Piedmont Lithium have restarted commercial spodumene concentrate production at their jointly owned North American Lithium (NAL) project in Quebec’s Abitibi-Témiscamingue region in March 2023.
• Several mining companies of northwestern Ontario, such as Frontier Lithium, Green Technology Metals, Lithium One Metals, Avalon Advanced Materials, High Tide Resources, Rock Tech Lithium and Imagine Lithium are working on lithium mining projects currently.
• The abundance of lithium in Manitoba has been reported, which could potentially raise this province as key source of the critical mineral hub in Canada.

Current trends in lithium extraction

Currently, there are two major ways of extracting lithium from its natural sources: 

Ore mining: Lithium minerals mainly exist in the form of aluminosilicate pegmatites (spodumene, lepidolite, zinnwaldite, etc.) in nature. Spodumene and lepidolite are the most typical minerals which have been used for lithium extraction. Traditional mining processes include geological surveys and exploration for lithium-rich mineral deposits within hard rocks.  For lithium extraction, these mineral rocks are heated and pulverized to form fine powder which is combined with chemical reactants, such as sulfuric acid to form a slurry. The slurry is heated, filtered, and concentrated through an evaporation process to form commercial grade lithium carbonate. 

Drawbacks: 

• Requires time and money-intensive techniques that need heavy machinery and water resources.
• Pollutes local environment, ecology, and disrupts local communities.
• Leaks or seepages can lead to contamination of surrounding ground water pools, rivers, and soil.

Evaporation of lithium brine: This operation involves pumping brine to the surface and distributing to evaporation ponds. The brine remains in the evaporation pond for several months until most of the water is removed through solar evaporation. The concentrated brine is then processed by treating with chemicals for precipitation of lithium followed by extraction and purification.

Drawbacks: 

• The method is inefficient and time-consuming (10-24 months for concentration of brine).
• The method is not suitable for all geographical locations, as it requires a dry climate and abundant sunlight.
• Varying lithium concentrations in different brines and the inability to extract higher amounts.
• The vast area of land used for the evaporation are left as salt dessert, causing detrimental effect on environment.
• Causes air and water pollution.

Future trends in lithium extraction

Recently, Direct Lithium Extraction (DLE) is emerging as a promising technology for the lithium extraction from brines. Several approaches for DLE have been developed and systematically investigated as listed below:

• Precipitation: Precipitation is a method used in wastewater treatment to remove dissolved ionic components from aqueous wastes by adding counter-ions to reduce their solubility. The dissolved ions thereby turn into solid particles. Precipitation of lithium ions from brine has been done commonly by chemical agents such as carbonates, phosphates, and aluminates. 
• Adsorption: Adsorption is the method of selective extraction of lithium by applying adsorbents. Using this technique, lithium ions physically attach to the adsorbents while unwanted ions remain in the feed solution, enabling lithium to be extracted from brines. The materials used to extract lithium ions include titanium, manganese, and aluminum-based adsorbents. Aluminium-based adsorbents are considered to have a higher adsorption capacity for lithium. Among other adsorbent materials, spinel-type lithium manganese oxides (LMOs) have attracted more attention from academic researchers as well as the industry due to their feasibility, excellent selectivity, and high lithium uptake capacity.
• Ion exchange: Ion-exchange technology applies a proprietary sorbent designed to be highly selective towards lithium ions. It efficiently removes most impurities and reduces large volumes of low-grade brine into a high-grade lithium concentrate. Strong acid cation-exchange resins, impregnated with lithium-selective inorganic sorbents can be used to selectively collect and recover lithium from brine waters. Some of the selective lithium sorbents for ion exchange include inorganic crystalline solids such as various aluminum hydroxides, aluminum oxides, manganese oxides, and titanium oxides.
• Solvent extraction: Solvent extraction, also called liquid-liquid extraction (LLE), is a method used to separate compounds according to their relative solubilities into two immiscible liquid phases – an organic phase, and an aqueous phase. Solvent extraction techniques for lithium brines can be applied using crown ethers, multicomponent systems consisting of an extractant, a synergistic co-extractant, a diluent, and ionic liquids. Lithium metals extracted into an organic, non-polar phase are typically recovered by use of an aqueous stripping agent, commonly an acidic solution, such as hydrochloric acid.
• Membrane separation technology: This method applies selective membranes that allow permeation of smaller monovalent ions, including lithium, but reject larger divalent ions, thereby separating lithium from mixture of ions present in brine. A novel membrane-based lithium recovery process is recently reported that combines membrane distillation (MD) and nanofiltration (NF) to concentrate a brine solution containing lithium and to remove divalent ions.
• Electrodialysis: Electrodialysis is a membrane separation process that uses an electric field to aid the movement of ions across a semipermeable membrane. Electrodialysis for lithium extraction is dependent on the use of a lithium-selective membrane and has components, anodes, and cathodes, which are similar to the technology in lithium-ion batteries. The extraction of lithium ion from brines have been reported to be achieved by electrodialysis using commercially available anion-exchange membranes and electrodes of lithium iron phosphate (LiFePO4) and iron (III) phosphate (FePO4).
• Supercritical fluid extraction: A supercritical fluid (SCF) is a material that can be either liquid or gas, used in a state above the critical temperature and critical pressure where gases and liquids can coexist. Due to their low viscosity, high diffusivity and low surface tension, supercritical fluids have demonstrated enhanced mass transfer across the interface between phases and therefore have been suggested as great option for extraction of low concentration lithium from brines. The supercritical fluid, CO2 is ideal for a closed loop lithium extraction process due to its moderate critical point (31.1°C and 72.9 atm), non-flammability and non-degradability (Tester Group, Cornell University). Supercritical CO2 has been applied for lithium extraction using strategically designed crown ether extractants.
• Nanotechnology: A metal organic frameworks (MOFs) nanoparticles has been applied by EnergyX for direct lithium extraction technology. MOFs are crystalline and highly porous materials. They are promising for a wide variety of applications such as storage, separation, sensing, proton conduction and drug delivery. The MOFs ion-imprinted membranes, consisting of polymers that exhibit perfectly sized vacant sites for target Li ions, have been applied for various Lithium extraction processes like nanofiltration, selective electrodialysis, membrane distillation and ion exchange.
• Porous fibrous strings: Researchers at Princeton University have developed a lithium extraction technique where a set of porous fibers twisted into strings. When dipped in a salt-water solution, the water travels up the strings through capillary action and eventually evaporates, leaving behind salt ions such as sodium and lithium, which can be harvested.

Challenges and environmental impact of DLE technologies from brines

• Most of the brines have very low concentrations of lithium, which makes most of the DLE methods inefficient.
• Many DLE technologies might require larger freshwater volumes than current evaporative practices, compromising their applicability in arid locations.
• A high Mg/Li ratio of brines requires large amounts of lithium precipitant, which results in huge amount of solid waste generation and higher costs.
• High concentrations of other interfering cations such as sodium and potassium in the brine co-precipitates along with Lithium which makes Li extraction more complicated.
• Adsorption and ion-exchange methods show good performance for DLE, but the cost and poor durability of adsorbents and ion-exchangers limits their application at an industrial scale. 
• Solvent extraction process could be promising but the disposal of spent solvents at a large scale may present environmental challenges.
• The wastewater discharge regulations are not clearly defined by municipalities for the processed and spent brines.

In conclusion, lithium is currently in high demand worldwide due to its potential applications in batteries and electronic products. The existing methods for lithium extraction from its natural sources like ores and brines are expensive, time consuming and pose environmental concerns. Scientists are investigating different physicochemical processes to develop a cost effective DLE technology for an efficient extraction of Lithium from brines. However, the major challenges of all DLE technologies are the low concentration of Lithium and high concentrations of interfering cations in the brines, and the higher cost of extraction. An innovation in direct Lithium extraction from its natural sources would be revolutionary for the global vehicles’ electrification and decarbonization.