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Amid significant environmental concerns over the impact of more widespread lithium mining, several methods of extracting battery material from brine could offer a cleaner solution and revive a historic Cornish industry.
Demand for lithium is increasing and pricing agency Benchmark Mineral Intelligence (BMI) expects a lithium materials market of one million tonnes by 2024 and a compound annual growth rate of 15% through 2033.
Analysts including BMI anticipate the onset of a lithium shortage around 2029 amid environmental and political concerns about the required expansion of lithium mining and processing and its concentration in a small number of countries.
Lithium is largely produced through open-air evaporation of brine, in South America’s “lithium triangle,” or hard-rock mining, primarily in Australia. China, which processes that Australian material, has domestic hard-rock and brine mining capacity. BMI estimates that 34% of lithium is mined in Australia, 28% in South America and 20% in China.
Energy-intensive hard rock mining relies on diesel-powered mining equipment and high-temperature processing. Concentration and evaporative brine treatment, while producing lower CO2 emissions, consume a lot of water in arid regions, raising concerns about overexploitation of aquifers. The resulting opposition to the projects means the lithium mining industry is slow to react to fluctuations in demand.
Direct lithium extraction
Direct lithium extraction (DLE) approaches offer an alternative by extracting lithium from brine using thermal or chemical processes. BMI estimates that the method accounts for 4% of lithium today and will reach 12% by 2030.
“Some commercial projects have been in operation for years,” said Federico Gastón Gay, senior lithium analyst at BMI. “Now there is renewed interest. Mining and oil and gas companies are looking at DLE and have the money and expertise to develop it.”
The water used during DLE can be returned to the aquifers. DLE processes are often powered by electricity and in some cases the same brines could also be used for geothermal energy generation.
“Our DLE approach means there is minimal depletion of groundwater aquifer water and, if used with renewable energy as we intend, there are minimal emissions associated with operations,” said Steve Kesler, executive chairman and interim CEO of Cleantech Lithium (CTL). The company is ramping up DLE projects in Chile and operates a pilot processing plant producing eluate that is processed by a third party into battery-grade lithium carbonate, ready for testing by battery suppliers.
Gaston Gay noted that while there is potential, the industry’s claims about reduced environmental impact still need to be proven. “In most cases, brines are reinjected, so in theory the aquifer balance doesn’t change,” he said. “DLE operations also occupy a fraction of the land required by evaporation ponds. These differentiations could make a big difference to environmental credentials, but there isn’t enough information available to definitively say it’s cleaner.”
The largest of CTL’s planned extraction sites, Laguna Verde, is estimated to contain around 1.8 million tonnes of lithium carbonate equivalent. Initial drilling and a pre-feasibility study are underway, after which CTL will seek investors, offtake partners and debt funding to cover the estimated construction cost of $450 million for a full-scale DLE plant at the site.
DLE production costs can vary widely depending on the composition, temperature and depth of the brine, as well as other conditions at the project site and the specific technology used. CTL’s Kesler said he expects the company’s projects to be “relatively low cost” compared to other lithium mining operations. Gastón Gay, meanwhile, noted that DLE costs should compare favorably to those of hard rock mining. However, unlike conventional brine extraction, DLE substitutes natural evaporation in the sun for a more energy-intensive process. Additional treatments may be required before or after extraction, which also leads to a potentially higher cost.
New tricks
While DLE processes are commercially proven and already in operation, scaling up to a more significant market share will require new technologies and applications. Gaston Gay noted that the operational projects located in Argentina and China are more of an improvement on conventional evaporation than a completely new process and that a drastic scale-up of any process is likely to entail complications.
In a 2023 paper published in Nature Reviews Earth & Environment , scientists led by Argentina’s Universidad Nacional de Jujuy divided DLE technology into seven broad categories with varying levels of commercial development. “Some proposed DLE approaches, such as ion pumping or Li+ [lithium]-selective membranes, are entirely new and will require broader engineering efforts to reach industrial scale,” wrote lead author Maria L. Vera. “In contrast, other proposals, such as ion exchange, solvent extraction, or electromembrane processes, have been studied for decades… The challenge here is to adapt these methodologies to the complexity of lithium-rich brines.”
CTL says it has opted for one of the best-known processes as a risk-reduction measure. “Purification technology has been around for many years, across multiple industries including uranium and water treatment, so there is relatively little technological risk in the process,” Kesler said. “We have also sought to mitigate that risk by working with some of the most respected names in the industry.”
The availability of technological options should also make the DLE more adaptable to different site conditions. “At Laguna Verde, for example, we have been testing various adsorbents to understand which works best with our brine in terms of selectivity of lithium molecules and rejection of other minerals,” Kesler added. “Not all brines are created equal, it’s about working and optimizing the process and technology rather than having to reinvent anything.”
Diversified offer
Another reason for the recent buzz around DLE is its potential to greatly increase the amount of lithium available for extraction. At existing brine projects, BMI estimates that improved process efficiency with DLE could increase yields by as much as 670,000 tonnes per year. The process could also bring lithium mining to several new regions.
Vera et al. estimated that 50–85% of continental lithium-rich brines are located in the lithium triangle region, with China as the second-largest source. Geothermal brines and oilfield brines, with lower lithium concentration, are found in many more regions, but have not been considered viable because evaporation to the required concentration would take too long, or the deposits are located in regions without sufficient land or a suitable climate for open-air evaporation.
Several DLE test projects are underway in Europe, including Vulcan Energy Resources’ sites in Germany. Vulcan’s “phase one” project is expected to produce 24,000 tonnes of lithium hydroxide per year and the company has signed supply agreements from 2025 with several battery industry offtakers.
The Vulcan project, located in Germany’s Upper Rhine Valley, combines DLE with a geothermal power plant. Brines from several drilling sites are piped to the plant. The heat from the brines is used to generate electricity and the brines are treated to produce a pre-product – lithium chloride suspended in water. It will then be transported by truck to a site near Frankfurt, where it will be further processed, using electrolysis, to produce battery-grade lithium hydroxide.
Horst Kreuter, co-founder and chief representative of Vulcan Energy Resources, said the first geothermal cluster has started producing lithium chloride, which is being kept in storage pending completion of the electrolysis plant.
Vulcan has exploration licenses for other drilling sites around the Upper Rhine Valley and says the electrolysis plant could also be used to process brines shipped from further afield. “The electrolysis plant costs around $30 million, so you can’t put one on every site,” Kreuter said. “The plant is very flexible, we can add different pre- and post-treatments and we can work at different temperatures and pressures. We are planning ahead and starting to look at other areas in Europe as well.”
There are many other areas in Europe worth exploring for brines that could be suitable for DLE. In the south-west of the UK, Cornish Lithium is working on several projects and aims to produce 15,000 tonnes of DLE from several small sites by 2030.
Compared to the project in Germany, Cornish Lithium expects to find brines at lower temperatures and lower lithium concentrations. A temperature of around 80ºC is too low for geothermal energy, but may be sufficient to provide district heating for the local area. The lower concentration in the brine may also allow the project to make use of cheaper extraction processes and therefore scale up more quickly.
“The brine in Cornwall is very clean – it’s actually less salty than seawater,” said Neil Elliot, corporate development manager at Cornish Lithium. “Our most recent exploration found lithium concentrations of over 100 parts per million. That means we can look at membrane technologies and various other concentration techniques.” Working with membrane technology, such as reverse osmosis which is commonly used in water desalination, means DLE could also produce clean water for local communities.
Alternative hard rock
Alongside its DLE project, Cornish Lithium is developing hard rock lithium mining at another site in Cornwall, UK, which is expected to produce a further 10,000 tonnes per year of lithium hydroxide by 2030.
The company plans to redevelop a disused china clay pit and build a processing plant less than a kilometre from the site. Materials mined at the site could be processed very differently from the spodumene ore typically mined in Australia. Cornish Lithium has worked with Australian company Lepidico to develop a suitable process. Life cycle assessments conducted at Lepidico’s project estimate a 40% reduction in carbon emissions compared to typical hard rock lithium mining. “Typically with a hard rock project you have to roast the ore at temperatures in excess of 1,000ºC,” Elliot said. “Instead we use a chemical process developed by Lepidico, which uses sulphuric acid to produce lithium.”
That route should also allow the company to produce battery-grade lithium hydroxide on-site without further shipping or processing. “The idea is that we get to a final product in Cornwall that we can ship directly to users in the battery industry,” Elliot added. |
