The lightweight metallic element lithium is the key ingredient behind our current generation of rechargeable batteries that power everything from our phones, personal computers, electric vehicles, and so much more, but traditional methods of extracting it from hard rock minerals such as spodumene or via evaporation from brine pools is a time-consuming, energy and/or water-intensive, highly polluting process.
The currently dominant method for producing lithium from hard rock involves heating the spodumene containing ore to over 1000-C (2300-F) for at least two hours to render the lithium bearing mineral porous enough for the second phase — another two-hour baking in sulfuric acid at 250-C (480-F). The resulting highly acidic solution must then be treated with additional chemicals to produce either the lithium carbonate or pure metal needed in industrial applications, all of which is quite costly in terms of energy use (including increased CO2 release) and the usual environmental degradation associated with mining and disposal of waste products.
For these and other reasons, extraction from brine deposits via solar evaporation ponds is generally seen as the more cost-effective way of producing lithium, but these deposits are available in economically viable concentrations in relatively few parts of the world — primarily South America (the lithium triangle of Chile, Argentina, and Bolivia) and China. But extraction from brine requires many months or even years to reach the point where lithium salts are concentrated enough to be ‘harvested,’ not to mention the considerable water resources needed in areas not noted for their access to water in the first place.
But now a team of researchers at Penn State have come up with a radically new approach to the lithium production problem that appears to be vastly superior to either of these traditional methods in all aspects, as reported in techxplore:
[Mohammad] Rezaee and his research group members, Chandima Hevapathiranage and Shihua Han... have a solution, though. With far less energy consumption and fewer harsh chemicals than traditional methods, their acid-free approach can extract more than 99% of a rock's available lithium in minutes, compared to the hours of conventional extraction that produces roughly 96% of the available lithium.
Just as an aside, note that these seem to be the same sort of people that MAGA-land and Trump don’t think need to be in our country at all, much less attending or teaching at our colleges and universities.
"What makes this approach especially promising is its compatibility with existing industrial infrastructure," Rezaee said, explaining that the new process is designed with scalability and practicality in mind, and it does not require extreme heat or the use of acids.
"It uses common materials like sodium hydroxide—a common compound used in making soap and found in many household cleaners—and water, and it operates at much lower temperatures than traditional techniques. That makes it not just cleaner and faster, but easier to implement at scale."
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"We used thermodynamic modeling to understand how the lithium-bearing minerals might interact with different chemical agents, and then validated those predictions through laboratory experiments," Rezaee said. "We found that mixing the lithium-containing mineral, called spodumene, with sodium hydroxide, at relatively low temperatures converts the mineral into lithium-bearing water-soluble phases."
They also investigated the use of microwave heating for this low temperature reaction—similar to heating food in a microwave rather than an oven—to cut the processing time to just minutes.
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According to Rezaee, the process can also work to extract lithium and two other critical minerals—rubidium and cesium, which are used in electronics, quantum computing, solar panels, atomic clocks, satellite navigation systems, batteries and even as a rocket propellant—from lepidolite, another rock ore. It can also extract lithium from clay sources.
The team is now working toward scaling up their approach and refining the process for industrial application.
That last part about extracting lithium from low-grade sources like clay is really key here. Lithium is widespread throughout the planet’s crust in various clay minerals, but usually not at a concentration that would make them economically viable with traditional extraction methods. If their new process really is efficient enough to make extraction of lithium from common clay economically attractive, then a major barrier toward constructing a much greener lithium-based economy has just been removed. Their paper was first published in the Chemical Engineering Journal back in February, and they’ve just been granted patent rights on their new process.
