Lithium Extraction from Geothermal Brines in the Salton Sea Region; Free, Prior and Informed: How America Failed the Indigenous in the Permitting of the Thacker Pass Lithium Mine

Technical Abstract
This report details the design and feasibility of retrofitting a geothermal energy plant in the Salton Sea region of Southern California with a brine-based direct lithium extraction (DLE) facility. The proposed plant produces ~15,000 metric tons per year of battery-grade lithium carbonate (99.5 wt%) to address the growing demand for lithium driven by its role in electric vehicles (EVs), renewable energy storage systems, and consumer electronics. By implementing DLE technology in the Salton Sea region, this project offers an alternative to environmentally harmful practices like evaporation ponds to meet increasing lithium demand.
The facility is designed to process brine at a flow rate of 6,000 gallons/minute at 110 °C and 1 atm. This report outlines key components of the DLE process, including brine cooling, citrate mixing, adsorption and regeneration, precipitation, separatory units, and peroxide removal. Each stage is optimized for thermodynamics, kinetics, material balances, and equipment design to maximize efficiency and achieve high-purity, high-yield lithium carbonate production.
Economic analyses demonstrate that the proposed facility is currently not financially viable due to prohibitive raw material costs. Further design work on citrate recycling and calcium removal is recommended to increase the profitability of the project. Beyond analysis of economic viability, this process prioritizes environmental and social responsibility. A Layer of Protection Analysis (LOPA) is performed so that safety considerations are thoroughly addressed.
In summary, while this process looks to provide a financial and environmentally sustainable solution for lithium production, additional optimization is required to reach commercial feasibility. Continued improvements in reagent recovery, brine pretreatment, and integration with existing geothermal infrastructure are key steps toward making brine-based lithium extraction a scalable and sustainable solution for the future.

STS Abstract
In 2023, Judge Miranda Du granted final approval for Lithium Americas to begin construction of what will be the largest lithium mine in North America when it enters production in 2027. Deemed a critical resource for both military and economic success, the Biden administration was eager to push a lithium project through the permitting process and into production as soon as possible. But, in so doing, the Biden administration and the Bureau of Land Management trampled on the rights of local Indigenous tribes, violating the UN’s standard of free, prior, and informed consent. This paper presents a case study of the mine permitting process of the Thacker Pass lithium mine through historical and policy lenses. My research includes an extensive literature review, including legal records, bills, articles, and podcast interviews - presented here in the form of a timeline of relevant events in the development, application, and lawsuit of Thacker Pass, a stakeholder analysis, and a regulation analysis. This paper reveals clear disparities between the intent of the free, prior, and informed consent standard and the operating standard of the Bureau of Land Management and recommends that the federal government enshrines free, prior, and informed consent in its legal requirements for federal land permit approvals. The paper also identifies two key changes that the United States must make to its mine permitting process: consolidation between departments and ensuring the selection of qualified individuals to lead permit reviews.
 
Synthesis
Lithium demand is expected to increase by nearly 3 times by 2030, reaching 3 million metric tons of lithium per year (Bloomberg NEF, 2024). Development of new lithium resources is clearly needed, so it is imperative that we carefully consider how and where this rise in production occurs.
Through my Thacker Pass research, I learned how difficult it can be to site a chemical plant or mine because of historical and environmental issues. Thacker Pass also provided a good benchmark for our geothermal brine lithium extraction process. Thacker Pass is projected to operate with a $2000/ton profit margin, whereas our proposed plant would operate at a $4000/ton loss margin, showing why Thacker Pass is under construction and our plant is in the theoretical stage. My STS research emphasized the importance of thinking about the social and societal implications of constructing a new mine or plant. Our DLE plant’s water use, though limited, might be significant enough in the arid Salton Sea region to warrant lawsuits during the development of the plant. Additionally, the land claims and complaints of farmers due to the use of certain chemicals, such as fuming hydrochloric acid, might be well justified.
Through the examination of the permitting process of a new lithium mine recently given the go-ahead, and the development of a new process to produce lithium, this thesis acts as a valuable tool for understanding the state of lithium development in America.

School of Engineering and Applied Science

Bachelor of Science in Chemical Engineering

Technical Advisor: Eric Anderson

STS Advisor: Joshua Earle

Technical Team Members: Patrick Boyd, Ian Forrer, Nicholas Goldstein, Mia Park