23/01/2025
Supply and characterisation of feedstock updates
During the M24 consortium meeting held in Karlsruhe (GER), the project team presented the latest progress achieved in the work package dedicated to the supply and characterisation of the feedstock, with a primary focus on the geochemical analysis of geothermal brines and rocks.
Between M18 and M24, researchers collected and sent for analyses geothermal brine from the reservoir at Soultz-sous-Forêts in France. This latest analysis not only revealed a Li concentration above 170 mg/L, which confirms the stability and the quality of this resource for a potential future lithium extraction in the Upper Rhine Graben geothermal brine.
In addition to brine analysis, the researchers conducted thorough geochemical analyses on core samples from three deep wells in Soultz-sous-Forêts. These wells intersect the Muschelkalk limestone, Buntsandstein sandstone and Visean granite formations. A total of 57 core samples, sourced from depths ranging between 841 to 5060 m were selected for analysis. The focus was on 36 granite samples, where the lithium concentrations varied significantly. According to the analysis of the research team at ES-G, Li concentrations tend to be highly impacted by hydrothermal alteration. They found that Li concentration can vary by two orders of magnitude when compared to the fresh granite mainly due to secondary minerals precipitation. However, solubilisation of Li is identified in most of the case where hydrothermal alteration is important.
Stakeholders interested in the characterisation performed by ES-G have the chance to find more detailed information at the upcoming Stanford Geothermal Workshop, taking place between 10 and 12 February 2025.
Further isotopic analysis of Li and Sr in rock samples will allow researchers to further understand the sources and mobilisation of Li in geothermal brines. These analyses will provide more accurate insights into the geochemical processes involved and support the development of more efficient and sustainable lithium extraction methods.
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