Metal detector: CMU researcher working on new ways to find lithium
MOUNT PLEASANT, Mich. (WOOD) — While it may not rise to the level of the 19th-century gold rush in the western United States, the shifting technological landscape has started a surge of its own.
With the automotive and industrial worlds turning away from fossil fuels and toward battery-powered vehicles, lithium has become an elite commodity. A report from USA Today found that the price of lithium went up 500% from 2021 to 2022, and manufacturers are using more lithium than is currently being mined.
Though there are many suspected lithium deposits in the United States — including one location in Nevada that is believed to hold billions of dollars’ worth of the metal — American companies largely rely on foreign sources for it.
A researcher at Central Michigan University hopes to change that, starting with an easier way to find it.
WHAT IS LITHIUM?
You don’t have to travel far down the periodic table of elements to find lithium. With the atomic number of 3, it is the lightest-known alkali metal.
Lithium is used in a number of ways — included in things like drugs, lubricants and even hydrogen storage. It has also proven to be key in several alloys, allowing a structure to maintain its strength without adding much weight.
But its primary service, especially going forward, is its role in rechargeable batteries. Compared to other metals, batteries made with lithium can power devices for longer and also have a longer shelf life.
Lithium doesn’t occur naturally as a metal. Primarily, it is found within the water of most mineral springs. Right now, most of the world’s lithium is produced in Chile, Argentina and Bolivia, taking advantage of continental brine deposits. Remember that Nevada property worth billions? That’s the Silver Peak lithium mine, the United States’ only continental brine lithium mine in the U.S., according to the British Geological Survey.
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But lithium can be found in other places, even if it may be more difficult to identify. You can find traces of lithium in most rocks, but to make financial sense, lithium companies want to find rocks that are lithium-rich to get the most bang for their buck. That can be boiled down to a select group of pegmatites called LCT.
Pegmatites, according to the U.S. Geological Survey, are a type of granite or igneous rock characterized by its giant crystals. Some of them contain high volumes of rare metals like lithium, cesium and tantalum (LCT).
Pegmatites are first formed more than 10 miles below ground. But over time, tectonic forces push the rock formations higher while erosion works away topside, bringing pegmatites closer to the surface until they can be uncovered by miners.
But how do you know you are sitting on pegmatites? And how would you know if they are rich in lithium? That’s where Mona Sirbescu and her team comes into play.
HOW DO WE FIND IT?
Sirbescu is a geology professor in CMU’s Department of Earth and Atmospheric Sciences. She said the methods for finding lithium can be relatively primitive, but they are evolving.
“The current methods are more of a shotgun approach,” Sirbescu told News 8. “They use boots-on-the-ground kinds of methodology, sending geologists and geological technicians to collect rock specimens and look for natural rock outcrops. It’s not always easy because many terrains in North America are covered by forests or glacial sediments.”
She continued: “(There are also) remote sensing methods to figure out the uneven topography of the terrain. These rock bodies, pegmatites, tend to stand up. So they can be determined from satellite images. And then there are even newer methods that are used when big funding is involved. Geophysical methods, airborne sensors, detecting the radioactivity of the materials or the magnetic properties or the density of the materials. All of these contrasts in the physical properties of the rocks can indirectly reveal whether there are pegmatites or not in the subsurface.”
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Sirbescu, partnered with a lithium company in Wisconsin, is leading research focused on identifying the key indicators within soil to give miners a more accurate estimate to whether or not their bedrock is rich in pegmatites and if it contains heavy levels of lithium.
“We were contacted a couple of years ago by a lithium company. We were asked to develop a pilot exploration project focused on about 10 square miles in an area of northeastern Wisconsin,” she said. “We had already studied the mineralogy, the mineral components of these rocks in detail and already published a bunch of papers in scientific journals starting about 15 years ago. But now with new research funds from this lithium company and from our own Office of Research and Graduate Studies at CMU, together with my team of students, we conducted fieldwork in the area and came up with this multi-faceted way of integrating different methods.”
One of Sirbescu’s key strategies is soil sampling.
“Soils form directly through weathering of the bedrock — both pegmatites and their host rocks. So, the soils potentially carry the chemical signature of the rocks beneath the soil cover,” she said. “So we are expecting to find a chemical anomaly or chemical halo around these bodies or in the soil above the bodies.”
Her team uses tools and analytical equipment available to them at the university to determine the exact chemical makeup of the soil. Then, working with a fellow researcher in Brazil, the data is entered into an algorithm that determines the lithium potential for the bedrock.
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Sirbescu said that teamwork is key to making scientific progress.
“It’s a really interesting development and I couldn’t have done it without my collaborators, my international collaborators, and the partnership with the lithium industry,” Sirbescu said. “My colleagues here in the Department of Earth and Atmospheric Sciences, who were very instrumental and very supporting in developing this project. And some of the biggest benefits really for me as a researcher and professor at CMU is working with my students, including a bunch of undergraduates who are very passionate and very eager to learn. One of my biggest satisfactions is to help them achieve their career goals and see them get started on their careers.”
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