The Thacker Pass Lithium Mine is a lithium clay mining development project in Humboldt County, Nevada, which is the largest known lithium deposit in the US and one of the largest in the world. There has been significant exploration of Thacker Pass since 2007. The Bureau of Land Management issued a Record of Decision approving development of the mine in January 2021. Construction began in March 2023 after an emergency appeal was denied by the court. The project site would cover , with less than of that being mined, on a site west-northwest of Orovada, Nevada within the McDermitt Caldera. The mine is a project of Lithium Nevada, LLC - a wholly owned subsidiary of Lithium Americas Corp, whose largest shareholder is the world's largest lithium mining company, Chinese Ganfeng Lithium. At full capacity it would produce 66,000 tons annually, equivalent to 25% of the current (2021) demand for lithium globally, which is expected to triple over the next five years. Development of the mine is driven by increasing demand for lithium used in electric vehicle batteries and grid storage of intermittently generated electricity from sources such as solar power or wind power. In late January 2023, car giant General Motors announced it would invest $650M in the mine project, giving GM exclusive access to the first phase of production.
The project has met resistance in the form of legal challenges and direct action. Several indigenous tribes with traditional homeland in the area oppose the project. These tribes have stated that Thacker Pass is a sacred site, a massacre site, and that they were not adequately consulted by the Bureau of Land Management. Opponents of the mine have voiced concerns about rushed environmental review, threats to critical wildlife habitat, disruption of cultural sites, and links between resource extraction and missing and murdered indigenous women. Proponents of the mine have stated that the project is necessary to limit climate change by reducing carbon emissions from American cars, is benign in its social and environmental impact, and will create 300 long-term jobs in rural Nevada, paying an average of $63,000 per year. The New York Times reported that controversy around the mine is "emblematic of a fundamental tension" between green energy and damage caused by resource extraction required for those technologies.
Resources
The Thacker Pass lithium deposit has measured and indicated resources of 13.7 million tonnes of lithium carbonate equivalent, at an average ore grade of 2,231 ppm (0.22%) lithium. The Thacker Pass volcano-sedimentary deposit is the largest known sedimentary lithium resource in the U.S.
Lithium Americas estimates that the site contains recoverable lithium worth $3.9 billion. It is estimated that enough for batteries for about a million electric vehicles a year could be mined.
Mining and extraction process
Thacker Pass would use a newly developed process to extract lithium from the clay deposit. Usually lithium is mined by either hard rock mining or brine mining. This mine will use hydraulic shovels to remove the clay and turn it into a slurry. Non-lithium-containing sand and rock will be separated and immediately returned to the pit.The lithium-bearing clay slurry would be mixed with sulfuric acid to extract the metal. A plant would be built on-site to burn molten sulfur and produce sulfuric acid, which is safer than transporting sulfuric acid, and would result in one third the number of truckloads necessary. Sulfur is a byproduct from oil refineries, and may be sourced from as far away as the Alberta oil sands. The facility would produce 5,800 tons of sulfuric acid per day, requiring 75 semi-trucks of molten sulfur to be delivered daily from Winnemucca. Burning the sulfur to produce sulfuric acid is an exothermic reaction, allowing the plant to generate most of its own electricity.
After the slurry is reacted with sulfuric acid, it will be pressed through filters which separate the elemental lithium solution, and then processed into lithium carbonate or lithium hydroxide for batteries. The tailings will then be returned to the pit. (The mine will use a process called "block mining", whereby previously excavated sections get filled with tailings as the operation progresses.)
The mine is planned to operate for 46 years, with the first 20 years removing material above the water table, with Lithium Americas intending to do studies over a decade on the water flows around the pit in hopes of proposing a safe method for mining below the water table (for which they are not yet permitted to do.)