(456b) Toward Sustainable Lithium Production: Process Modeling, Techno-Economic Analysis, and Life Cycle Impacts of Recovering Lithium from Geothermal Brines

Lithium is an essential primary element for catalyzing the shift towards renewable energy due to its extensive utilization in battery systems for energy storage [1-3]. As the global adoption of electric vehicles is projected to increase dramatically by ten times [4], coupled with the commitments made at COP28 to triple renewable energy production by 2030, the escalating lithium demand will ultimately strain its availability [5]. While salt lake brines have served as a primary source of lithium, the economic and environmental viability of other types of brines (e.g., geothermal or seawater) with moderate lithium concentrations have not been fully evaluated for large-scale lithium production. Specifically, there is a lack of sufficient data on pre- and post-recovery brine processing (e.g., unit operation type, operating conditions, key process parameters, etc.) for this purpose. Additionally, a systems engineering approach is necessary to identify process integration opportunities to reduce energy and water consumption), which are prevalent issues in current lithium processing systems [6-7], while producing high-purity lithium carbonate (the favorable lithium product for battery systems.

In this work, we construct a comprehensive process model for lithium recovery from geothermal brine feedstock using chemical precipitation. The brine undergoes a solvent extraction process to remove boron, followed by a three-stage precipitation process. In this precipitation process, divalent ions are removed, and LiCl is converted to Li₂CO₃ We use the chemical composition of Salton Sea geothermal brine [8] as our primary feedstock and model the proposed process in the SuperPro Designer V13.2 software to produce high-purity lithium carbonate (99.5 wt.%). Moreover, we assess process feasibility and its environmental impact using techno-economic analysis and cradle-to-gate life cycle assessment (LCA). Our economic analysis shows that producing 4 tons/hr lithium carbonate with 99.5 wt.% purity requires a brine feedstock with an initial lithium concentration of 450 mg/L or higher to have a positive net present value. Additionally, on-site production of the chemical precipitants leads to a reduction in operational costs by approximately 3 times, while posing challenges in terms of environmental sustainability. The LCA results show that in certain evaluated impact categories, such as water use and ozone depletion, on-site production of precipitants leads to a 40% increase in water usage and a 4-fold higher contribution to ozone depletion. Hence, while economically feasible large-scale production of battery-grade lithium carbonate production is possible from unconventional feedstocks using chemical precipitation, the on-site production of chemicals may lead to less favorable environmental impacts despite reducing operating costs.

References:

[1] U.S. Geological Survey. (2023). Mineral Commodity Summaries 2023; Available at http://pubs.usgs.gov/periodicals/mcs2023/mcs2023-lithium.pdf.

[2] Xu, P., Hong, J., Qian, X., Xu, Z., Xia, H., Tao, X., Xu, Z., and Ni, Q.-Q. (2021). Materials for lithium recovery from salt lake brine. Journal of Materials Science 56, 16-63.

[3] He, X., Kaur, S., and Kostecki, R. (2020). Mining lithium from seawater. Joule 4, 1357-1358.

[4] International Energy Agency (IEA). (2023) . Global EV Outlook 2023 Catching up with climate ambitions. Available at : https://www.iea.org/reports/global-ev-outlook-2023/prospects-for-electric-vehicle-deployment

[5] Alliance, G. R., & Presidency, C. (2023). Tripling renewable power and doubling energy efficiency by 2030: Crucial steps towards 1.5° C. Available at : https://www.irena.org/Publications/2023/Oct/Tripling-renewable-power-and...

[6] Vera, M. L., Torres, W. R., Galli, C. I., Chagnes, A., & Flexer, V. (2023). Environmental impact of direct lithium extraction from brines. Nature Reviews Earth & Environment, 4(3), 149-165.

[7] Khalil, A., Mohammed, S., Hashaikeh, R., & Hilal, N. (2022). Lithium recovery from brine: Recent developments and challenges. Desalination, 528, 115611.

[8] Ventura, S., Bhamidi, S., Hornbostel, M., Nagar, A., & Perea, E. (2016). Selective recovery of metals from geothermal brines (No. DOE-SRI-6747). SRI International, Menlo Park, CA (United States).