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Author: ÉS-GÉOTHERMIE [ÉS-G]

Among European geothermal sites, the Upper Rhine Graben (URG) has a great potential for a lithium (Li) production from geothermal brines due to its high concentration and the significant water flows exploited by the geothermal power plants in this area.

Despite its great potential, certain gaps in the basic knowledge of the geochemistry of the URG rocks are persisting, as there is scarce conclusive investigation carried out in the past to estimate the Li content as well as the mechanisms of Li recharge in brine. Identifying Li-rich geological units are essential to target areas with higher Li concentrations for exploration and to ensure the sustainability of this resource.

In geothermal systems, hydrothermal fluids circulate through the fractured and porous rock formations, undergoing complex interactions with the surrounding lithology. Various processes, such as leaching, dissolution, and precipitation, can occur and they can significantly influence the concentration of Li in the circulating fluids. Knowing the chemistry of the reservoir rocks could help us understand chemical reactions occurring between the hydrothermal fluids and the rocks and therefore how Li is mobilised and transported into the geothermal brine.

In the LiCORNE project, ESG is conducting detailed geochemical analysis of several core drill including granite, sandstone, and limestone from geothermal wells drilled in Northern Alsace. Researchers finalised the rock sampling task at the beginning of 2024, while the chemical measurements are expected at the end of June, current year.

AN ES-Geothermie employee sampling of granite rocks in the core shelter.

Sampling of granite rocks in the core shelter. © ES-Géothermie (ESG)

In total, 57 samples were collected and closely studied, which facilitates understanding of the chemical elements behaviour in the rock before and after the hydrothermal circulation/alteration. Comparing the results of this on-going investigation with the few data available in literature and referring to the Li concentration in URG rocks could reveal an unexpected behaviour of Li in the geothermal reservoir rocks.

After careful analysis of the chemical composition, isotopic analysis of the same rock will follow which will show more accurately potential sources of Li in the geothermal brine.

A. Fresh monzogranite sampled at 1774.5 m depth); B. Hydrothermally altered granite showing argillic alteration sampled at 2159.30 m depth

A. Fresh monzogranite sampled at 1774.5 m depth); B. Hydrothermally altered granite showing argillic alteration sampled at 2159.30 m depth. © ES-Géothermie (ESG)

 

Extraction of concentrates, waste cathode material, ore and tailings

Using alkaline leaching process on spodumene concentrate, the maximum extraction of Li achieved thus far reached 75%. The leachate transformation, even after the filtration step, hinders the sample analysis and further processing. To overcome this challenge, upcoming experiments will explore  elevated temperatures, diverse additives, and further investigate the chemical precipitation process.

During the advanced solvometallurgy applied on spodumene concentrate, the research team at TECNALIA reported high Li leaching yields (>95%). Their future work will focus on the further optimisation of the operational conditions, more appropriate for the anticipated scalability phases of the process. On the other hand, solvometallurgical tests carried on waste cathode material achieved high leaching yields for all target elements (Li, Co, Ni, Mn) using mild operational parameters.

After the first experiments engaging reactive milling and aqueous leaching [treated with aluminium- (Al) and calcium (Ca) – salts] on waste cathode material, researchers at KIT reported close to 31% Li recovery rate. Samples supplied by UMICORE were leached under different conditions to extract Li – available in the form of Li carbonate [LiCO3], and further subjected to purifications processes employing various reducing agents. Future efforts for this particular task will focus on adjusting leaching temperatures, establishing an optimal purification process, and evaluating Li recoverability in both Al and Ca systems.

Separation and purification of Li from solutions

Anticipating future upscaling phases, researchers at VITO, working on the Li-sieve adsorption and desorption from aqueous leachates, shaped the lithium-titanium-oxide (LTO) adsorbents into spheres, which enabled dynamic testing. The team is currently optimising the flow rates for adsorption and desorption to model the optimal conditions for upcoming processes. While initial tests utilised synthetic Li solutions, upcoming research will extend to purification processes for spodumene leachates.

In the same work package, TECNALIA performed experiments using different organic solvents for the liquid/liquid (L/L) extraction from brines showing promising Li yields in the range of 40-60%.

Within the same work package, EnBW scientific team has been working on designing an eco-friendly Li-desorption process from brines, focusing on the development of novel synthesis for Mn-based adsorbent material. Notably, the successful upscaling of the synthesis process from 2,5g to 200g marks a significant achievement in sustainable material synthesis.

Finally, the last task of WP5 – Electrode-based Li adsorption and desorption from brines, conducted by KIT, presented the conclusions of their research work carried during the last six months, which includes a 4-step process. Their work has been focusing recently on the optimisation of the electrode pre-treatment, the establishment of the current densities and the reduction of the Na contaminations. Despite high Li selectivity rates obtained thus far, their work in the upcoming months will centre around optimising the recovery efficiency and the selectivity. Future experiments will test different thermal operating conditions (40°, 60°, 80°), but will also attempt to scale-up the process.

Recovery as battery-grade chemicals

In the final technical work package, SINTEF scientists are pioneering a two-step process which involves in a primary phase selective chlorination by converting insoluble oxides to soluble chlorides; this is followed by a second step – electrolysis of the soluble chlorides extracting the target elements. After conducting different chlorination experiments, researchers emphasised the importance of time and the processing duration, confirming over 65% Li recovery rate. With promising results, their focus pivots towards the second step – electrolysis.

Read the next article for a comprehensive overview of the meeting.

Lithium (Li), a highly versatile element, finds extensive applications in diverse industries including ceramics, glass, fuel cells, metallurgy, pharmaceuticals, aerospace, and lithium-ion batteries (LIBs). With the demand of LIBs increasing, particularly fueled by portable electronics and electric vehicles, the global lithium industry is undergoing rapid expansion. Due to its lightweight and reactive properties, Li is considered the essential component in high-energy-density batteries, playing a crucial role in the future of sustainable energy. But the extraction of Li resources has become a critical concern.

VITO employs an innovative process known as Gas-Diffusion Electrocrystallisation (GDEx) technology to achieve the direct extraction of Li, that leverages gas-diffusion electrodes to orchestrate a meticulously controlled chemical transformation. By precisely manipulating its parameters, GDEx enables synthesis with minimal chemical additives, marking a significant milestone in this field. The unique design of the reactor maintains a consistent set of conditions, and by simply altering the inlet solution, it can produce the desired target structure. This approach is highly scalable and promising for the future of Li extraction and synthesis.

Achieving over 95% selective Li recovery from geothermal brines

Following comprehensive investigations performed on synthetic solutions, VITO fine-tuned the operational parameters to be applicable to natural brine solutions and leachates. The experiments carried out on diverse brine solutions yielded remarkable results, with a Li removal efficiency exceeding 95% from these solutions. The planned process involves producing layered double hydroxide structures which can further be downstreamed to battery cathode material.

Learn more about the GDEx process in the previous article: Recovery as battery-grade chemicals

©Adobe Stock Photos, Salinas Grandes, a huge salt flat in Jujuy and Salta, Argentina. Its lithium, sodium and potassium mining potential faces opposition from indigenous communities and environmental activists.

 

In July 2023, International Energy Agency (IEA) released its inaugural “Critical Minerals Market Review”, along with their new online data explorer. Between 2017 and 2022, the demand of lithium (Li) tripled, primarily due to the energy sector’s reliance on it. According to the report, the market for energy transition minerals is poised for continued rapid growth, placing increasing pressure on the global mining industry.

Looking in particular at the Li price fluctuations, the study reports increases in 2021 and early 2022, accompanied by strong volatility. However, the latter half of 2022 and the beginning of 2023 saw more stable trends, albeit still remaining above historical averages.

Not unexpected, investment in the development of critical minerals, particularly Li, recorded a significant surge of 30% in 2022, building upon a previous increase of 20% in 2021. The IEA analysis examined the investment patterns of 20 major mining companies actively involved in the production of minerals essential for the energy transition. It revealed a substantial rise in capital expenditure specifically allocated to critical minerals. This upward trend can be attributed to the favourable momentum propelling the adoption of clean energy solutions, such as the most recent EU Regulation on Batteries and Waste Batteries. According to the IEA analysis, companies specialising in Li development witnessed 50% rise in their investment spending. Fuelled by the rising demand of electric vehicles, large industrial groups are competing now in a quest to secure mineral supplies: General Motors announced a 650  million USD in Lithium Americas, while Tesla confirmed already plans to build a Li refinery in Texas (USA).

Along with its ‘Critical Minerals Market Review 2023’, the IEA also launched the IEA Critical Minerals Data Explorer, an interactive tool that facilitates access to the agency’s projection data.

LiCORNE Project and EU’s Vision for the Energy Transition

The IEA analysis conclusions raise the concern of the diversity supply. The LiCORNE project was launched at the encounter of European aspirations to advance the energy transition. The project aims to increase the European Lithium (Li) processing and refining capacity to produce battery-grade chemicals from ores, brines and off-specification battery cathode materials. Over a span of 48 months, from the 1st  of October 2022 to the 30th of September 2026, eight research and development centres in Europe will investigate no less than 14 new technologies for extracting, recovering and refining Li.

Currently in its first year, the LiCORNE project completed the task of characterising and providing materials for the R&D activities.  Most of the materials are sourced from European resources, including spodumene and Li-rich mica from mines in France and Austria, and geothermal brine sampled from the Upper Rhine Graben (France and Germany). The synthetic brine is prepared in UK. Only continental brine and off-specification cathode material originate from non-European countries – Chile and Korea.

For more information, refer to the detailed article, and explore the available Li resources in Europe.

VITO achieves direct lithium extraction, using the Gas-Diffusion Electrocrystallisation (GDEx) technology. GDEx uses gas-diffusion electrodes to achieve this goal, by producing in-situ the necessary quantities of mild chemicals, which in turn form precipitates containing lithium.  

During this period, the GDEx team has conducted experiments with synthetic solutions. The effect of adding chemical supplements to the process is being investigated to optimise the lithium recovery yield and selectivity vs. competing ions in solution. After optimising the GDEx process with synthetic streams and learning about the precipitating mechanisms, we are looking forward to extending the process in various geothermal brine solutions obtained from the consortium partners. After precipitation in the form of layered-double hydroxides, the GDEx team will investigate the downstream steps to obtain battery-grade lithium hydroxide. 

More information about the GDEx process can be found at http://gdex.vito.be