Mining metals and minerals from seawater

[BLANK_AUDIO] It's a pool of different ions like cadans and anions and seawater. Starting of course from chloride, we have a lot of sodium chloride. [BLANK_AUDIO] Seawater also contains lithium, scandium, vanadium, gallium, indium, boron, molybdenum, and rubidium. >> Basically, everything you can find on the periodic table is in the ocean. [BLANK_AUDIO] That was Alex Ivanov at Oak Ridge National Laboratory, Haikaglada at the University of Braiman, and Chinmei Subin at Pacific Northwest National Laboratory. They are all scientists and engineers whose research takes a deep dive on an elemental elixir that most of us call seawater. You're listening to stereo chemistry. I'm your host, Ariana Remmel. In this episode, we'll talk with researchers from around the globe who are developing ways of extracting a variety of elements from the world's oceans. It's the next installment in our series about water and the ways it intersects with the environment, society, and chemistry. To tell us more about the future of seawater mining, we've invited C&N Physical Sciences Reporter and Team Lead, Mitch Jacobi on to the pod. Hey, Mitch, good to have you here. >> Hi there, Ari. >> So Mitch, the first thing that comes to mind when I think about the ocean is stuff like sunny days on the beach, swimming, vacation stuff mostly. But Alex, Haikagl and Chinmei just spouted off a list of ingredients that makes it seem like I've been taking a dip in some sort of elaborate chemical soup. >> Yeah, that's certainly one way of putting it. And I think that most people, even most scientists, don't go straight to metals, elements, and chemical separation technology when they're relaxing along the seashore. But there's a lot of stuff in the deep blue sea, besides saltwater and marine life. And some of that stuff could one day power energy infrastructure all over the world. So today on the pod, we'll hear from scientists in the United States and European Union about why they're interested in extracting elements, especially metals from seawater, and how they're using chemistry to do it. >> Speaking of energy resources, my ears pricked up at a few of the elements in that first list, like lithium. We did an episode with C&N Business Reporter Matt Bloice about mining lithium from brines in the Saladada comma in Chile. And El Dorado Arcansoff here in my home state. >> Right, that's because lithium is a critical material for making batteries and other electronic components that run today's tech world. Hike calls it white gold because it's so critical for our modern energy systems. And there are lots of other metals that make today's technology possible. Indium, for example, is used to make solid oxide fuel cells and high strength alloys for aerospace engineering. Scandium, another transition metal, is found in television screens and solar panels. The ocean even has rare earth metals that power next generation electric car batteries and uranium. That's a critical fuel source for nuclear power plants. You know, those plants produce almost 20% of the electricity in the United States today. >> But why live to the ocean? Aren't there easier ways to get uranium like mining it straight from the ground? >> Good question. That's what I asked Cere Brown, who also works at Oak Ridge National Laboratory in Tennessee with Alex. >> In the case of uranium, with the current consumption that the US is using for the nuclear fuel, the majority of that uranium actually has to be purchased from other countries. About 80% of the uranium used in nuclear power plants in the US have to be purchased. The rest of your sources of uranium may run out within about a hundred years. So it's a matter of long-term national energy security. Most of the world currently gets its uranium from Kazakhstan, Russia, Uzbekistan, and Australia. But as Cere said, those land-based sources, mines, they may run out within a century. >> So that's the situation with uranium. What about the other elements used for electronic devices? >> Other energy critical elements are in the same boat, so to speak. For example, around 95% of the world's supply of India and Scandiniam comes from mines in China. >> Okay, so let me make sure I've got this right. These various metals and minerals are important for energy security and for computers, electronic devices, and all the high-tech gadgets that we depend on for just about everything in the modern world. But there are only a handful of countries worldwide with terrestrial mines that source these critical minerals. >> Right. Some of the people I talked with are US national labs, and others are part of a large European Union project called C for value that's spelled C-S-E-A, the numeral four value, C for value. The country's funding this research, want to ensure that there's a stable and ample supply of energy critical elements, a supply that isn't affected, for example, by political or economic instability outside of those countries borders, and that's why they're trying to extract them from seawater. >> Ah, so we are back to the high seas. Just how much of these metals is actually in the ocean anyways? >> A lot. Here's Saria again. >> The amount of uranium in the seawater is about 1000 times of the uranium from terrestrial sources. >> Wow, so you're telling me that there is 1000 times more uranium in the world's ocean than in all the land sources combined. >> Yep, that's exactly right. >> Okay, well, what about the other elements you mentioned? >> Well, because of the enormous size of the oceans, there's plenty of the other elements too. Like Chinmay from Pacific Northwest National Laboratory said earlier, just about every element on the periodic table is out there floating in salt water. >> I'm guessing there's a catch. >> There's a huge one. Here's how Chinmay put it. >> Some of the elements say sodium, magnesium, calcium, potassium, and things like that. They're in much higher concentrations. But the oceans also have lithium, rare earths, and all the other energy-critical elements that we might be interested in extractive. But the challenge is they're in much lower concentrations. >> Oh, sure. That makes sense. >> But how dilute are we talking here? >> That's what I asked Alex. >> When I talk about uranium extraction, so students always ask him, "Where is uranium located?" I've never seen uranium and sea water when I go to the beach. But it's there, all kind of valuable metals, transition metals, and uranium are all there. But you won't see them in their original form, like in the form of metal or even salt, because they're dissolved there. So they present there at really low concentrations. In case of uranium, it's 4 milligrams per ton of water. Can you imagine? So this kind of very, very dilute concentration. >> Wait. So is Alex saying that in a ton of sea water, that's 1,000 kilograms of salt water, there's just 4 milligrams of uranium? >> Yeah, that's it. But remember, there's a whole lot of water in the sea. So that number adds up. >> Sure, but that dilution ratio makes the proverbial needle in a haystack sound quaint. How on earth do folks extract what is essentially a few specks of dust from tons and tons of sea water? >> That's a very good and long-standing question. Alex gave me a primer about the history of this endeavor. >> Those started in 1990s by Japanese scientists. It actually can be explained, because Japan depends on the imports from uranium more than USA right now. So if you look at geographical location of Japan, it's surrounded by oceans, right? So there is a great temptation to grapple this uranium and use for their needs. Maybe that's why they were the first one who provided the proof of concept for this technology of mine and uranium from sea water. >> He actually pointed out that there was an even earlier effort to mine uranium from the oceans by scientists in the UK. But the Japanese researchers went much further. >> The first technology was a platform-based technology. So in this kind of technology, they processed this polymeric absorbance into stacks. And this stacks the Lord into sea water. And the idea was that the ocean currents would move this stacks through the water extracting uranium. >> It turns out though that that way of doing things was too expensive. And the uranium uptake was too low. >> So they switched to another technology, braided fiber technology, where they produced this amydoxin fibers. >> What kind of fibers? >> Amidoxin fibers. Amidoxin is an organic functional group, a certain arrangement of carbon, nitrogen, oxygen, and hydrogen, with a carbon-nitrogen double bond. People studying uranium uptake from water at that time examined a whole slew of functional groups. And it turns out that the amydoxin group is particularly good at snagging uranium in its dissolved form. That's the urineal, or U02 cation. >> So the idea is that you immerse this braided fibers onto the bottom of the ocean bed and then attach them there. So there is a kind of radiotransmitter attached to this fibers. And after a certain period of time, for example, after one month, it sends a signal to a ship to detach it from the bottom of the ocean bed. And then it floats back to the surface straight forward recovery. >> So it's a similar strategy to the prototype that used stacks of polymer sheets to passively soak up dissolved uranium. Did these researchers notice an improvement with the amydoxin fibers? >> They sure did. >> They found that they can extract 1.5 grams of uranium per kilogram of adsorbent after 30 days of deployment. It was a landbank discovery because they kind of were saying that, "Hey, this technology can work. The only catch was just to make this technology financially viable." And that's what we've been doing. So what are Alex and the other scientists doing now to improve on this technology? Well, one strategy that Sirri mentioned is fine-tuning the polymers, mostly acrylic or polyacrylonitrile, and the Amodoxine Functional Group. It turns out that that group comes in an open molecular form and a more closed or sicklic form, and they don't behave quite the same way. From what we and other scientists have found is that the cyclic structure actually grabs the uranium in larger amounts than the open chain structure. However, even though the cyclic structure grabs more uranium, it likely grabs a lot of vanadium along with it too. So like right now one of the movement in research is to get more selectivity towards uranium. Yeah, that's a classic chemical separation conundrum. It's hard enough extracting uranium from the ocean without having to sort through whatever else the fibers stop up. Exactly. Another research area is tailoring the way functional groups are positioned along the polymer chain. The Oak Ridge group and their co-workers found that some arrangements of alternating Amodoxine and carboxylate groups work well together, mainly because of carboxylates, water-loving nature. We found synergistic effects that not only the Amodoxine group that plays a role, the carboxylate groups next to them also help push the uranium towards the Amodoxine group better. And all the fine-tuning of the polymer absorbent has really paid off. Right now it went up to like almost 8 grams per kilogram. A few years ago it was between 5 and 6. Yeah, wow. That sounds like a big boost from those earlier devices. What about separating the uranium from the fibers? How do they do that? Alex and Sirri explained that the usual way is by treating the absorbent with strong acids, then collecting the metal as a precipitate. That's another area of research people are working on nowadays using milder methods in reagents like hydrogen peroxide and sodium by carbonate. So that's where uranium stands now. The work is still in the research phase. So regarding commercial use and industrial applications of this fibers, I think it's still kind of far from reality. Alex is giving a pretty frank assessment. There are up to 8 grams of uranium per kilogram of fiber, but he says the target is more along the lines of 15 to 30 grams. Even so, he's pretty upbeat about it. There is nothing impossible. Maybe we'll come up with some other functionality or even different technology for mining uranium. And we will be able to mine it from sea water in the future. So I'm optimistic about that. Wow, that's really cool, Mitch. I'm excited to learn more, but let's take a quick break first. Then we'll continue our journey around the world to explore other strategies for mining precious elements from our planet's salty seas. Hi listeners. Did you know that CNN has an app? I'm Rochelle Adkins, CNN Senior Product Manager, and I'm so excited to share that our mobile app. Chemistry News by CNN has a fresh new design that makes it easy to read your favorite chemistry magazine on the go. All standard N Premium ACS members get instant access to the latest news from CNN right on your phone. With the CNN app, you can bookmark your favorite stories, download entire issues, and you'll be the first to know when a new issue has been published. Chemistry News by CNN is available for all iOS and Android mobile devices. So head over to the App Store now and search Chemistry News by CNN. That's Chemistry News by C and Percent EN. You can also find a link in the show notes. And we're back. I'm here with CNN Physical Sciences reporter Mitch Jacoby. So Mitch, what are some of the other ways scientists have tried to mine elements from seawater? Right. So earlier we heard about how Alex, Suri, and their colleagues are developing materials that you lower into the ocean where they passively pull out uranium from the water column. But out in Squim, Washington, Jinmei Subin at Pacific Northwest National Laboratory is tackling the dilution problem head on. Squim is actually a very small town. It is a beautiful place with snow cap mountains and oceans all in a very small area. And it's right near the Olympic National Forest. So from scenic coastal Squim, Jinmei discussed some big picture concepts about extracting minerals from water. One of them was about the type or the source of water used for this work. There's large volumes of water that have to be processed. And we know that processing water, moving water, pumping water is all very, very energy intensive. So that's where being creative about how we extract minerals and what sources we use, whether we pre-concentrate it, it comes important. Pre-concentrating the minerals? How does that work? One approach is by taking advantage of desalination plants that extract fresh water from a salty stream of seawater. That process produces the drinking water that comes out of the tap for millions of people in the U.S. alone. So when you extract the fresh water what's left behind, the waste stream is what we refer to as a waste brine or a desalination brine. And the brine has the same salts you start out with, but it's a bit more concentrated because the water has been removed from it. So the brine is a little bit easier to work with in terms of extracting elements that may be in low concentration. So where are these desalination plants? Everywhere. They're all over the world. A quick web search tells you that there are more than 16,000 desalination plants installed worldwide. That number may be a lot higher depending on how you count them. And when it comes to taking advantage of this existing infrastructure, Chen Mei and her team at PNNL are in good company. I also spoke with researchers from a project in the European Union called Seafirm Value. The brine from desalination plants is the starting point for all of Seafirm Value's mining work. One of the researchers working on this project is Sandra Meica with Erocat Technology Center in Spain. Here's what she told me. We want to develop a process capable to recover several metals and minerals. In conventional mining, the objective is to recover only one mineral or salt or metal. In this case, we want to recover up to nine. To do all that, this EU Seafirm Value project is bringing together 16 partners from Spain, Germany, Italy, Belgium, Ukraine, the Netherlands, Finland and Switzerland to conduct fundamental and applied research. We have a lot of universities involved from around Europe. We have also some companies that make research for technologies. Then we have also Seavot Resalination Plans Operator. Our objective is that desalination plants can be the new minds of the future. Much like the work going on elsewhere, the Seafirm Value research is still at the early stage. And because of intellectual property rights and so forth, most of the results aren't yet ready for public consumption. But Sandra and her colleagues shared a number of things. For example, one focus is boosting the concentration of the salts and desalination plant primes above standard levels, so that the subsequent steps, the separation steps, work even better. Okay, so how do they do that? Well, one way is by using better water evaporation technology and desalination plants, specifically, re-engineered evaporator tubes to pull out even more fresh water and further concentrate the brine. That's Hike Gladis Specialty at the University of Braemen in Germany. We heard from her at the very beginning of this episode. Innovations for evaporator materials have not been made for years. She says everybody uses metal tubes, but the high chloride content in the brine rigs havoc on the pipes. So that means plant operators need to use corrosion resistant metals that are expensive, heavy and prone to fouling. So Hike Steam is taking a different approach. We are developing poly-mayor composite evaporator tubes made of polypropylene filled with graphite flakes. Polymers can bypass the shortcomings of metals that Hike mentioned, the high cost, high weight and so forth, but they tend to be lousy heat conductors, which is really important for water evaporation. That's why they're doping the propylene tubes with graphite, a really good heat conductor. Okay, so they're getting better at making super concentrated brines. What's next? Like, how do you separate the metals? One strategy comes from Evelina Repo at La Parantalla at the University of Technology in Finland. In our group, we have created a new approach for this separation technologies. We have started to develop 3D printed ionic chains or adsorption materials. With this 3D printing, we can produce optimal structures that contain optimal porosity, and we can optimize the flow rates, reduce the energy consumption when we pump water to be treated through those materials. - The way Evelina explains that they're modules like high-tech filter blocks, each one customized for a specific metal. She says it'll be used in series in a flow-through device. The idea is that the brine is pumped through at one end, and as the solution passes through the modules, each one selectively pulls out one of the metals, producing a bunch of pure streams. - Okay, so this incorporates some of the absorption strategies we heard about from Alex and Cere, but with a different keylating substrate for each element, yeah? - Basically, that's the way it works, and Evelina's team is already testing their new setup. - We are getting good results already. At the moment, our modules are very small. - Small for now, but the plan is to scale up. In fact, all of the technologies the C for value people are developing will be scaled up and integrated into a mobile testing facility they call moving lab. - So what's the plan for this moving lab? - Sandra said all of the gear will be collected and assembled in a mobile lab, and the lab will go in a shipping container and sent off to be tested at a real-world deceleration plant in the Canary Islands. The plan is to evaluate all the technologies on a number of brine streams at that location. - Wow, that is really cool. But we're coming to the end of our story here. So what did these researchers tell you about what the future of seawater mining could look like? - Yeah, that's a great question. Everyone I spoke with was so full of energy, but very realistic about large-scale implementation being pretty far down the road. And it's also important to remember that while this research is primarily based out of labs in the US and EU, the technology these scientists are developing could have global implications. So I'd like to leave you with something Chinmei said about her hopes for the future. - We need to think about seawater as an equitable resource. I think it's very important to not be bogged down by the fact that it is low concentration. We need to think creatively about how we put different technologies together so we can make it a more economically viable option. - It leaves me feeling cautiously optimistic about the real world benefits we could all share from the oceans that connect us. - This episode of Stereochemistry was written by Mitch Jacobi with audio editing by Mark Feuer de Tusson. The episode was produced by Carrie Jansen and me, Ariana Rimmel. Full credits for this episode are in the show notes. Stereochemistry is the official podcast of chemical and engineering news. CNEN is an independent news outlet published by the American Chemical Society. Thanks for listening.