Lithium (Li) is currently in high demand due to its use in batteries for electronic devices, particularly laptop computers, cell phones, and electric and hybrid vehicles. Spodumene and subface brines are the sources of lithium used in cathodes of lithium-ion batteries. The USGS is interested in lithium because it is an energy critical element with great promise in new technologies, in addition to its current uses. While USGS has published mineral deposit models for lithium brines and lithium clays, these general conceptual models did not include 1) the recognition and description of the co-occurrence and potential interaction between lithium clays and brines within continental basins, and 2) an explanation of why the type of clay and the structural position of lithium within the clay mineral will affect industry's ability to economically extract lithium from clay.
We are conducting a laboratory project designed to measure the chemical partitioning of lithium between lithium-bearing clays and lithium-brine solutions. Our research hypothesis is that the partitioning of lithium between basin sediments and pore water brines will be governed by the chemical equilibrium reactions of cation exchange and mineral solubility. Our research goal is to predict the equilibrium concentration of lithium in brine pore water as a function of lithium concentration in clay. Ours is a 2-pronged research approach: first we will conduct laboratory experiments designed to measure the partitioning of lithium between lithium-bearing clay and brine solutions when the system is at equilibrium and also during mineral dissolution and cation exchange reactions. Second, we will test our experimental models with measured data for lithium partitioning between basin sediments and brines, which we collect from the scientific literature and our colleagues and collaborators in the lithium exploration industry. Our final product will be predictive equations and graphs, for estimating lithium concentration in brine pore waters, given lithium concentration in clays. It is anticipated that a partitioning model can be an exploration tool for lithium brine deposits, and used to estimate the lithium concentration in a brine from sediment analysis.
Geology, Minerals, Energy, and Geophysics Science Center