Researchers at the University of Wyoming Carbon Management Institute (CMI) discovered a vast new lithium resource near Rock Springs during a geological carbon dioxide storage site characterization project sponsored by the U.S. Department of Energy.
Preliminary analyses of fluid samples collected from a well drilled on the Rock Springs Uplift — a geological feature in southwest Wyoming — suggest that reservoir brines from a 25-square-mile area of the uplift could contain 228,000 tons of lithium: enough to meet annual U.S. demand.
To help put this number in perspective, the lithium reserves at Silver Peak, Nev. — the largest domestic producer of lithium — total 118,000 tons in a 20-square-mile area. In a best-case scenario, the 2,000-square-mile Rock Springs Uplift could harbor up to 18 million tons of lithium, equivalent to about 720 years of current global lithium production.
CMI scientists discovered lithium dissolved in the highly saline fluids, or brines, contained within Wyoming’s most promising CO2 storage reservoirs (the Madison limestone and Weber/Tensleep sandstone) on the Rock Springs Uplift. Before CO2 can be safely and successfully stored, these brines must first be removed from underground geologic formations to manage pressure in the reservoirs during CO2 injection. If the brines remained in the reservoir formations during injection of liquid CO2, the resulting pressure increase could fracture the reservoir rocks and allow CO2 and other substances to escape. Removing brines from the reservoirs makes room for injected liquid CO2 while keeping pressures at safe levels and maintaining the integrity of the confining rocks.
“Due to their high salinity, brines from the CO2 storage reservoirs would have to be pumped to the surface and treated — often an expensive process. Recovering and marketing lithium from the brines would produce significant revenue to offset the cost of brine production, treatment and CO2 storage operations,” says Scott Quillinan, CMI’s senior hydrogeologist.
“Although other researchers have evaluated the economic potential of producing metals and salts from saline oil field brines, incorporating lithium production into the CO2 storage process is a new concept,” CMI Director Ron Surdam says. “Several factors make southwest Wyoming ideal for testing this process.”
First, production of lithium from brines requires soda ash (sodium carbonate), and importation of soda ash to lithium production facilities often represents a large expense. However, the Rock Springs Uplift CO2 storage site is located within 20 to 30 miles of the world’s largest industrial soda ash supplies, so the costs of soda ash delivery (by rail, truck or pipeline) would be minimal.
Second, magnesium must be removed from brines before they can be used for lithium recovery, which makes the entire lithium recovery process more expensive. Fortunately, the brines from the Rock Springs Uplift reservoirs contain much less magnesium than brines at existing, currently profitable lithium mining operations.
Third, brines must be heated and pressurized before lithium can be extracted from them. However, because the Rock Springs Uplift brines lie so far underground, they are already at a higher pressure and temperature than brines at existing lithium operations. This would allow operators to essentially eliminate this step in the process, resulting in significant cost savings.
“In addition to lithium, the brines contain other recoverable, economically valuable metals and salts. Also, the treated water resulting from the recovery process could benefit local communities, agriculture and industry,” says Fred McLaughlin, CMI’s senior petrologist.