S2 E76: Rethinking Rare Earth Separation — Chloe Tolbert, Idaho National Laboratory

Dustin [00:41]: Hey everyone, welcome to the Rare Earth Exchanges Podcast. I'm your host, Dustin, joined by Daniel, and today our guest is Chloe Tolbert, who is a researcher at the Idaho National Lab. She joins us along with her colleagues Bob and Travis, who we've interviewed on the show before. Chloe, welcome to the show. How are you doing?

Chloe Tolbert [01:03]: I'm doing great. Thanks so much for having me.

Dustin [01:06]: Yes. So Chloe, as a researcher at the INL, you specialize in critical mineral recovery and recycling. Correct? Perfect. So could you give us just a quick summary overview of how you got started in that area and kind of what led you to INL?

Chloe Tolbert [01:26]: Sure. I actually started on at INL as an intern. my PhD advisor had gotten involved with an INL project and they needed a student to do some of their work, and so I offered to come up and one thing led to another. I did a postdoc appointment at INL and then became staff just about a year and a half ago. So I've been here a little bit over four years. My

Chloe Tolbert [01:53]: The work that I do now related to critical materials is completely different from what I started on in grad school, but I stuck around so I clearly really enjoy it and yeah, that's how I got here.

Dustin [02:07]: That's exciting. And sounds like really important stuff. And I know the word stuff is a bit is a poor word choice, but it is pretty vital the work that you're doing in terms of just recycling and extracting rare earths from discarded electronics, things like that. So I would be curious to know just a

Chloe Tolbert [02:11]: Absolutely.

Dustin [02:30]: bit more of maybe the specialty of of what you're

Dustin [02:33]: doing today and and and maybe some of the challenges or even the small wins that you guys have experienced.

Chloe Tolbert [02:40]: Sure thing. So my focus at the laboratory is mainly on electrophoretic separations, and I'll broadly call that field-assisted separations. and so what this is, is it's sort of a a transformation from typical solvent extraction approaches that one might think of for rare earth element separations. So we know that rare earth elements like the lanthanides have extremely

Chloe Tolbert [03:06]: similar physicochemical properties. They share an oxidation state, similar acidity, very similar size. And as a result, they're really difficult to separate. And so through approaches like solvent extraction, you can, you know, exploit equilibrium and different chemical properties to eventually end up with purified lanthanides or rare earths, any any critical material of your choice. But that process is really capital intensive. The

Chloe Tolbert [03:34]: organic extractants that are used in the process can be very costly. it takes hundreds of stages, it's not very selective, and ultimately we can't do it domestically due to the environ environmental burden that it creates. And so field-assisted separations are one of our solutions to being able to deploy those highly selective rare earth technologies domestically. So electrophoresis uses an electric field to separate any charged species in a solution. If something's positive, it's going to move one way. If it's negative, it'll move the other way. So it's more of a transport-based approach than anything, but we add in a spice of chemistry by incorporating different ligands. These are aqueous organic ligands, usually very simple in chemical structure, environmentally benign. So think of things like acetic acid, which is just vinegar, or even lactic acid, citric acid. simple molecules like that can actually impart crazy differences in electrophoretic mobility of rare earth elements once you put them in an electric field. And so a lot of my work currently focuses on how can we understand the structure-function relationships between some of these ligand systems? Why

Chloe Tolbert [04:52]: Does this class of work ligands work way better at separating lanthanides than something slightly different? You know, what what's going on there with the chemistry? And then also, what can we do to bring this technology to scale? And so a lot of our focus is there currently.

Daniel [05:11]: I just wanted to ask you a critical question. First of all, kudos to you, Chloe, for what you're doing because it's critically important. As we know, state of the world today... just about every rare earth element is separated in China through a very environmentally intensive process, as you know, that we're going to have a hard time replicating over here, I believe. And so what you're doing is a critical national security exercise. So with that being said, could, for the audience, and we have different types of folks that are coming here,

Chloe Tolbert [05:34]: Absolutely.

Daniel [05:48]: Could you maybe just simplify even a little bit more the solvent extraction approach in China versus what we're trying to innovate in and maybe just simplify it so that people can get a better understanding of what these two things are and how they're different.

Chloe Tolbert [06:06]: Absolutely. Apologies. I'm I'm used to to talking technical all day, so

Daniel [06:10]: No, it's okay. It's okay. We have a mixed audience. There's investors that are getting into this. So there's different levels.

Chloe Tolbert [06:19]: Absolutely. So solvent extraction. It's I'm gonna call it a legacy technology. hopefully I don't offend anyone by saying that, but it's basically you have an organic phase, your oil phase, and then aqueous phase, any anything water soluble. And aqueous phase is where your solubilized metals such as lanthanides, Other critical metals, say gallium, germanium, any solubilized metal species in solution, it's going to be acidified in that aqueous layer. The organic layer is what's going to contain your extractants. And so these are the things that can get really costly. There's been a lot of research put into improving these extractants so that they're incrementally more selective. And you shake that up. You shake that mixture up. Water and oil are not soluble. And so what happens is at the interface there's sort of a a constant action of those extractants pulling metal species out of their aqueous phase into the organic phase. Those metals are now bound to a ligand in that organic phase. Do that hundreds of times, and you can start to gradually. Get one metal over the other. It's very, very difficult for lanthanides, but unfortunately it is the status quo. But you can imagine having half the volume just being comprised of organics. Waste management is very difficult. And so that that's one issue. The the cost of developing these extractants is another issue you have to worry about.

Chloe Tolbert [08:01]: Cost, again, that's mostly associated with any reagents that you need or the extractants themselves, and it's again not selective. It does work. there's a reason it is the status quo is because it at the end you will get a separated product. it's just not a very sustainable way toward that product at the moment. So some of the Advantages of electrophoretic technology over solvent extraction is that you can do this completely in an aqueous environment. So highly applicable for feedstocks like dilute waste waters, geothermal brines, you name it, anything, anything aqueous, right, we can use. and again, there's not really an issue with the ligands themselves. They're all water-soluble. they're very inexpensive. You know, I gave the example of. Citric acid, lactic acid, those are widely available. There's no shortage anytime soon. and the selectivity is really one of one of the big, big advantages of this approach. You can separate all 14 lanthanides from one another in a single pass of ligand-assisted electrophoresis. this is something that I and L has unique capability in, and we're sort of a leader in that space at the moment.

Daniel [09:05]: So if I just may, because that's kind of crazy what you just said. mean, the solvent extraction process in China and Inner Mongolia, for example, I believe about on average how many pass throughs, how many times do they have to cycle through to get that final product? I've heard like tens, if not hundreds of times.

Chloe Tolbert [09:37]: It's usually hundreds. I don't want to misquote the exact number, but I would say at least one hundred passes to separate praseodymium and neodymium, which are traditionally two of the most difficult adjacent lanthanides to separate from one another. And that's just for those two. That's not considering how many passes it took to get the rest of the lanthanides separated out, right? So it's it's just significant.

Daniel [10:04]: And you're saying with this approach that you're doing up in Idaho, you've seen a separation process where one time you're actually getting the output.

Chloe Tolbert [10:18]: Yes, in one pass of about 10 minutes, we are cleanly separating with baseline resolution 14 lanthanides. Now the catch here, it's not the same volume that's being produced by solvent extraction. the separations that we're demonstrating at at this selectivity in this resolution is very, very small. Think nanogram to microgram quantities. It's highly effective, but really small quantities and it's done in a batch separation type mode. Now one project that I started working on last year and it's kind of been continuing is we're trying to now transition that technology to a continuous approach. So whereas right now we're using small 50 micron inner diameter capillaries to do these electrophoretic separations, we want to move that into sort of a flat

Chloe Tolbert [11:10]: Platinum rectangular type geometry where your electrolyte's constantly flowing through. You're applying an electric field perpendicularly. You're injecting continuously your rare earth mixture or critical mineral mixture or what have you. And as that's flowing, it's coming into contact with the ligands as well as being influenced by the electric field. And you can sort of diagonally start to deflect species out, and then you have. constant collection streams. And so that's our approach for moving this technology forward to start to achieve some of those kilogram per day quantities that solvent extraction is capable of.

Daniel [11:50]: Well, that would be so game changing if you could scale this up to go kilograms per day. mean, this is incredible. Dustin, if I may just ask a couple other questions. This is so fascinating, Chloe. I'm so happy you're on. Is this patented, this process? Like, has the lab patented it? like, where does it stand in terms of intellectual property?

Chloe Tolbert [11:54]: Absolutely. Absolutely. Thank you so much. Right. Yes, so we have a few patents out there currently, or I should say patent applications. Capillary electrophoresis in and of itself is it's an analytical laboratory technique. It's traditionally used for things like DNA separations, metal and even rare earth separations have been demonstrated over the years using different ligand systems. And so our patents mostly concern the specific ligand systems that we're using. So we have a couple there. We with that project, there's one patent application out there that covers the scale up, essentially. That's that's something that hasn't been done before. There are commercial instruments of free-flowing electrophoresis, but again, and very similar to the smaller analytical capillary electrophoresis, they've only been used in biological, pharmaceutical fields. Nobody's adapted that. for metal ion separation. So that's really where INL's leading leading the game right now.

Daniel [13:22]: It sounds that way. It's a very exciting topic and, you know, definitely after this we'll follow up and write more about this to the extent it's public and we can. Dustin, I have a few more questions, but if you'd like to...

Daniel [13:37]: Chime in.

Dustin [13:39]: Yeah, the one that came to my mind listening to you talk, Chloe, was the process sounds incredible, very efficient, but it's at a small scale. But what what is the is there like a certain type of feedstock that this process lends itself well to? Is it agnostic any feedstock works or what does that look like?

Chloe Tolbert [13:59]: That's a fantastic question. So currently the only requirement is the solution needs to be aqueous, right? the separation resolution that you'll get kind of also depends on the concentration of ligands that you have in your background electrolyte. That's really there are two big driving forces in this technology. Number one is the electric field, you know, the action of Separating based on transport rather than chemical physical properties alone. But there's also the ligand itself. You know, as a metal is making and breaking complexes with a ligand in solution, that's dynamically altering its electrophoretic mobility. So at each point, the charge of the metal ion, its overall diffusion coefficient or its size is changing. And so designing a ligand system that helps to maximize differences between, you know, praisiodymium and neodymium, for example. That's that's a huge thing and really where, in my opinion, the most interesting science is. but to to go back to your original question for are the what are the feedstock requirements? Aqueous, if it's a low concentration, even better. That means you can get away with using less ligand in your system, so you're driving costs down.

Chloe Tolbert [15:21]: but it's again, it's not inherently limited by whatever your concentration is. Obviously it would work great for more dilute type sources, but you know, eventually I see this being applied to concentrated liquors even. It really the challenge there comes down to can you design a ligand system that you don't have to have ridiculous concentrations of that can do a good enough job separating at a more modest concentration.

Dustin [15:59]: Interesting. I'm I'm trying to imagine w aqueous feedstock, you know, something that's got water part of it, what that might look like. we did have somebody on the show that they're they specialize in processing wastewater and extracting critical minerals there. So is that something you guys are experimenting with as well?

Chloe Tolbert [16:19]: For the electrophoretic separations, up to this point, we've just been using surrogates. but we've been including or trying to mimic the surrogates as compositionally relevant to what you might encounter from one of those wastewater streams. so we're throwing in random, or not random, calculated random,

Chloe Tolbert [16:42]: Cations and anions to try and confuse the ligand system to see, hey, is it robust enough to still separate with the same resolution that it had before at scale? Turns out it is. And so again, that really just comes down to the design of the ligand systems because some will work great, some may have a very similar structure. but it for whatever reason just will not perform the same as its counterpart and

Chloe Tolbert [17:09]: Yeah, a lot of interesting work going into why that is the case, but for now that's what we're seeing.

Daniel [17:16]: I wanted to jump in before we, Dustin, get into some other topics like the facilities, the critical mineral facility. Chloe, why are heavy rare earth elements harder to separate than the light rare earths? Why are they so much harder elusive, let's just say?

Chloe Tolbert [17:36]: Okay. Well

Daniel [17:38]: You know, they're harder to get right now. China basically controls like 98, 99 % of separation and refining. Is that something that you can address? If not, don't worry about it. But I'm just curious if that topic comes up, like terbium, for example.

Chloe Tolbert [17:46]: Right. Right. two main reasons I can think of. number one is just natural abundance of heavier elements is just naturally lower. And so there's not maybe as much of the heavier earths available as there are lanthanum and cerium, for example. that's you know, most mines have too much cerium or too much lanthanum in their in their ores. the second reason. In my opinion, is that as you go across the lanthanide series, the changes that you see between adjacent lanthanides are already small. but as you cross over about halfway from gadolinium to heavier, those differences become even smaller than they are for the lighter rare earths. And so it's even more of a challenge, maybe twice as hard to separate heavies than it is light rare.

Daniel [18:51]: Interesting, interesting. Well, I wanted to bring up the critical minerals building 55,000 square feet, I think is it with Idaho State University in partnership. Could you talk a little bit about that? What that's all about? What it's going to do? What the teams are doing there?

Chloe Tolbert [19:13]: Absolutely. So yeah, you're referring to our CME SIC building, and CME SIC stands for Critical Materials and Energy Systems Innovation Center. and having a dedicated facility means that for the first time, INL can bring the entire critical materials research ecosystem under one roof. so everything from mineral characterization to chemical and biological separation experiments to pilot scale processing can Happen in a single integrated space. So that helps to remove a huge amount of friction from the research process. Researchers aren't moving materials between multiple buildings, juggling schedules for shared equipment, or working around space limitations that would otherwise slow down experiments. It sounds like a simple thing, but it actually makes a huge difference in research productivity. but the building, yeah, it's it's large, it's purpose-built. The facility was designed, you know, with the right airflow, shielding, utilities, safety systems, chemical handling infrastructure that we need in order to perform these complex types of separation experiments. that we can do at scale. You know, you can't do these types of things in a traditional laboratory. You need the right infrastructure. so

Daniel [20:31]: Right.

Chloe Tolbert [20:32]: Yes, we're we're then able to test not only at bench top scale, but everything in between up until pilot scale. We can process real volumes of ores, brines, scrap metals, anything. and that's kind of you know, the critical step between the scientific idea and then industrial reality.

Daniel [20:52]: Yeah, and you know, just on that comment, we really need that in this country because, you have some private sector initiatives, but they're under pressure to do whatever they need to do for their timeline and their investors. We need infrastructure like what you all are bringing to the market to help companies, collaboratives, be a little bit more agile in testing, for example, ORS and such from different parts of the world. So really exciting. What's the timeline for companies that are watching that may want to contact Idaho National Labs? What's the timeline look like for when you're available to collaborate?

Chloe Tolbert [21:35]: I would say get in touch with us as soon as possible. Everything's happening really, really fast around here and we're trying to get things off the ground ASAP. So the sooner the better, in my opinion.

Daniel [21:47]: Got it. Okay.

Dustin [21:48]: Chloe, I am curious. With the association you have with Idaho State, are you guys seeing a lot of interest from students in getting into this field? we've we've talked to a lot of people, the businesses in the industry, and one of the biggest concerns that they always put out there is the need for talent. We can put money where it needs to be, we can build the facilities that need to be built, we can you know, get things in place but at the end of the day if we don't have people to run it, you know, what's it all for? and so I'm just curious if if there is hope at the college level

Chloe Tolbert [22:24]: Yes, I absolutely think there is. And as a matter of fact, we've seen a lot of interest from Idaho State. We've got students here. Some of our scientists even have joint appointment faculty there. The the collaboration has just been incredible and it's really nice to see the next generation of scientists take a genuine interest in this, right? It's it's tough. It it's a challenge and You know, again, going back to our CME SIC building, like that's that's just the perfect environment to have those types of collaborations. And yeah, everything's going well with it so far.

Dustin [23:05]: That's good. That's really good to hear. 'cause sometimes it's easy to get caught in the doomsday narrative sometimes, but I'm glad to hear that there's a partnership there and that there's interest coming out of the university to be a part of it, to learn, to accept the challenge. that's that's really great news. And I think a lot of people who are listening to this will probably also feel encouraged.

Daniel [23:30]: I will just say, know, Chloe, Dustin and I, we write about this too, that to have industrial policy, I mean, the science, what you're doing is really critical. And then we need a pipeline of a whole new workforce, right? that needs to be science driven. And for whatever reason, you know, the US sort of lost that edge over the past maybe four decades or something. People wanted to do other things. But now, you know, there's a recognition that we have to re-industrialize. We really have to. We have no choice. you know, for what you all are doing now, are you networked with other institutes? So, for example, other national labs,

Chloe Tolbert [24:02]: Absolutely.

Daniel [24:13]: and universities, is there some kind of forum where you can all come together and kind of take this collaboration to the next level?

Chloe Tolbert [24:21]: There is. so we have you know, just regular collaborations with universities. researchers will partner up with professors and work on projects together. That's nothing new. what is kind of newer for the INL landscape is our super partnerships that we have with certain universities. And so schools like Colorado School of Mines, Arizona State University, we have Essentially these agreements that make collaboration less of a hassle. It's supposed to ease our paperwork burden because that's you know, there's always paperwork involved when you wanna do any research. And so it's the entire intention behind these partnerships is to facilitate faster, more efficient research. And you know, I personally have a collaboration with the super university going on right now and I'm seeing the difference. You know, we're we're able to move funds faster if we need to get something over to the university. If, say, we need to use their equipment, or maybe they need our equipment or our services. a lot of that burden's eased by the super universities. Now, for national labs, most of the international lab collaboration right now comes from our metallic programs. And

Chloe Tolbert [25:40]: I believe that's comprised of nine different national labs. Bob would be able to say exactly, but I believe it's nine, working on various stages of the critical material's life cycle. So there's chemical or I'm sorry, comminution and beneficiation, your, you know, more physical separations or preconcentrations, there's separations, there's you know Manufacturing after that, all these different stages that different national labs are working on and they're working on collaboratively.

Daniel [26:13]: That's so exciting to hear. And the bureaucracy has to go away. I mean, for important things, we need to to streamline, right? just, we don't, you know, and the politics that comes in academia can be a bit much sometimes. It's actually worse in the corporate world in many cases. I want to say too, I think this is very important, and I don't know if you all are doing this, and we don't have to discuss it, other than we think there are key points around the globe that Idaho National Labs should be partnering with. So for example,

Chloe Tolbert [26:22]: We really do. Well I can imagine.

Daniel [26:49]: There are certain spots that we communicate with, like in Southeast Asia or in Brazil, where there's problems or maybe environmental problems. And there's lots of material to work with. And wouldn't it be nice if your laboratory and your collaboratives could work internationally and help show people a different pathway to not pollute as much? Right? Because in some parts of

Chloe Tolbert [27:15]: I couldn't agree more.

Daniel [27:17]: Yeah, so in some parts of the world, I mean, we're seeing an ecological disaster because of this stuff. this is something that America can do to leapfrog others, I believe. So no pressure on you, Chloe. I mean, we're counting everything on you. But on that note, I had a question that Dustin put together, or Dustin, you could ask it. I mean, I think it's the gap between research and

Daniel [27:44]: production between getting to a pilot and getting to a commercial. That seems to be the place where a lot of research goes to die. Dustin, do you want to elaborate on that question?

Dustin [27:58]: you almost said up for verbatim Daniel. Pretty close.

Daniel [28:00]: Yeah, okay. Okay, there, there. I saved you the trouble. mean, Chloe, how do we like, like how have you seen it's and you don't have to get into the details. But have you seen instances at Idaho National Lab where you have seen research, go to pilot, and then go to a commercialization or you seen that process getting closer?

Chloe Tolbert [28:25]: I have seen the pro the processes get closer. and that's just a a factor of me not have been at the lab so long. again, I've been in my role for about a year and a half and I have a project of my own that I'm trying to get up to pilot scale at the moment, but you know, of course we have our other collaborations, so Perpetua, US Critical Materials, I'm certain there's plenty more. Right. And so I'm lucky enough to be able to see that actually come to life in currently where I'm here at. But you're absolutely right. That that gap, that space between, you know, breakthrough in the lab and then actually a and actually producing commercial plant that's producing material at scale, that's huge, and it's huge for us to overcome. and so What we can do at the lab is we can make sure that our chemistry is working as we expect it to at the bench scale. We can then start to increase the size of things, but then you start to run into the problem of physics, right? Physics starts to change things. It then starts to become more of an engineering problem from that point on. And it's just all those little steps in between up until You know, we've we've got a pilot plant, we can demonstrate XYZs being separated at this specific rate with this efficiency, right? It takes a lot of testing to make sure you get the economics right though. That's one of the biggest issues and what kind of a lot of people get stuck on is not having enough or convincing enough information related to the economics and you know, processing costs overall. Is this worth it? Given this feedstock, can we get you know, c can we make this make sense? so

Daniel [30:19]: And I would say about that, you know, that's a really important point and we had a guest recently and I forget I think it was Tommy He works for L3 process. It would be great to connect you Chloe and him because his expertise is Doing that what they call the resource like mapping out the economics of these things. That's what they all they do so it'd be it would be great to see like a You I and L and L3 partnership, but you know

Chloe Tolbert [30:44]: I'm very interested. I would love their contact information if you don't mind.

Daniel [30:46]: Yeah, of course. And I was going to say, I'm an advocate of our government, the taxpayers, which is us, subsidizing this because this is a matter of national security. I frankly want my tax money to subsidize this if it helps us become independent for critical things like manufacturing, whether it's... in green energy to weapon systems. And we have to be able to do that, right? So the economics, which you have to make work, and then there's, there may be industrial policy to support this, to incubate it maybe for three to five years so that five to 10 years from now, the economics is sustainable. So I think we have to think about this and we have to, folks in Washington have to understand this, that this is beyond just a simple market solution. Because remember, our competition, they don't operate by the market. It's a complete state monopoly. There has been hundreds of billions to trillions of dollars subsidized. And it's getting deeper and more entrenched. Our mainstream media doesn't really go into it, but it's happening. So yeah, it's a very important topic.

Chloe Tolbert [32:04]: it's different for every researcher and it all depends on the funding source that you have. So we, you know, at any time can have one project that has a big pot of money that'll cover us for a year or two. and then you might have ten different projects going on at the same time that you're responsible for contributing ten percent of your time for each project. And so You know, I haven't really been a around long enough to see it fluctuate, but from what I've heard from our upper management and from senior researchers is that that it kind of fluctuates. You know, every few years the well will be full and then, you know, give it five years after the fact it dips back down, and so it's this oscillatory behavior. I am in a fortunate position where You know, with critical materials being such a hot topic right now, there's a lot of funding being allocated for, you know, different types of separation technologies, different scale-up projects, pilot demonstrations, things like that. And so yeah, hopefully as you know, interest continues to grow in critical materials and processing and innovative new technology development, PIs and researchers here have maybe one or two projects that they can put their full attention on. 'cause we're not scrambling for funding, right?

Dustin [33:29]: we've talked on we've touched on a lot of different topics. And so Chloe, I would just if we could summarize everything that you feel is important that you'd like to just communicate, what would you say?

Chloe Tolbert [33:42]: Sure, I just think it's important to reiterate how urgent this critical materials challenge is. And, you know, as a scientist, if there's one piece of advice that I could impress on your audience or on the next generation of researchers, it's we can't keep focusing on small incremental improvements to legacy technologies. We have to be taking risks. We have to be you know, vetting the chemistry associated with these risks os the engineering, what ha whatever it may be. I'm using chemistry terms 'cause I'm a chemist, but de-risk everything appropriately, but we can't I mean we have to take action. It's it's urgent now more than ever. It's only going to become more urgent. So it's it's really all hands on deck type of problem.

Dustin [34:39]: think that is well said. echoing the battle cry and and I think you're you're joining the throngs here at Rare Earth Exchanges when we say, Yes, this is an urgent thing. This is a critical issue that everyone should be paying attention to because it it's not going to go away. And it certainly will only get better if we put our minds and our our actions towards it. So

Chloe Tolbert [35:05]: Absolutely. Of course.

Dustin [35:05]: Chloe, thanks for being on the show and sharing your thoughts, your insights into the great research that you're doing over at INL. And maybe in the future we'll get you back on the show to get an update to see how things are moving along.

Chloe Tolbert [35:20]: Sure, I would love that. Thank you guys so much for the opportunity to speak about the stuff we do here.

Dustin [35:25]: Absolutely. Thanks, Chloe.