Dr. Doreen Kaiser, Prof. Martin Bertau, TU Bergakademie Freiberg, about LiPriSek


Carbonation of lithium-bearing primary and secondary raw materials using CO2

Prof. Dr. Martin Bertau, Dr. Doreen Kaiser (TU Bergakademie Freiberg)

CO2-WIN Connect: Prof. Bertau, Dr Kaiser, carbonation with CO2 and electromobility - how do you bring it together in your project?

Dr. Kaiser: In the CO2-LiPriSek project, lithium is obtained by carbonating lithium-containing raw materials. CO2 serves as the digestion agent, with which the contained lithium is selectively mobilised. Potential raw materials include lithium ores and black masses from used lithium-ion batteries (LIBs). The lithium mobilised by direct carbonation with CO2 is then precipitated from the digestion solution as lithium carbonate without the addition of further chemicals. This raw product is already of battery quality (purity > 99.5%) without an additional purification step and can thus be used directly for the production of new LIBs without the need for subsequent refining. This sustainably closes material cycles and ensures CO2-neutral battery recycling. The extremely low CO2 footprint proves that the COOL process is exactly what we need to tackle the tasks of the future.

CO2-WIN Connect: What is special about the approach of CO2-LiPriSek?

Prof. Bertau: Special about the CO2-LiPriSek project is the complete recycling of all ingredients. We no longer have any waste materials, only raw materials. The lithium content in the ores in question is very low at around 3%. The main part is siliceous accompanying material, which is only discarded in conventional processes. In our project, geopolymers are produced from these residues. These are promising CO2-free binders. They often have even better properties than classic cement. And they are completely recyclable. In the case of battery residues, not only lithium but also the accompanying metals (e. g. Co, Ni, Mn) are extracted and converted into marketable products. In this way, a holistic utilization of the raw materials is ensured. All process steps can be operated with renewable electricity, thus avoiding CO2 emissions. The CO2 released during combustion steps is the raw material for carbonation, making the process completely CO2-neutral. To cut a long story short, the time for excuses is over. Zero-waste and low-carbon footprint under economic conditions can already be achieved economically today. We don't need a debate on whether this works, we need a society-wide effort on how to bring more such processes into use.

CO2-WIN Connect: What about the purity and usability of lithium? Is it likely that it can be used in battery production for all purposes (e. g. energy storage in the home, car, mobile phone...) or are there limitations?

Dr. Kaiser: As already mentioned, the lithium is isolated in the form of lithium carbonate. Regardless of the reactant, the raw product already has a purity of > 99.5% and can therefore be used directly for the production of new batteries without the need for energy-intensive refining.

CO2-WIN Connect: The use of alternative sources for the extraction of lithium will play a decisive role for Europe in the transport transition. How do you assess the potential of your technology compared to the future demand for lithium in Europe or in Germany?

Prof. Bertau: The great advantage of our technology is that different lithium-containing raw materials can be processed into a marketable product in a comparatively simple way. The reactors required for this are state of the art, which enables rapid industrial implementation. Since the use of different lithium-containing raw materials is possible, the process is very flexible and can be quickly adapted to new challenges. The development of LIBs is far from complete, so there are a large number of different battery types on the market. Only a flexible process can be the key to success here. We work independently of origin, i.e. it does not matter from which source the lithium comes. What is important is the joint processing in a single process line. This automatically gives us primary product quality. That is true recycling in the literal sense of the word.

CO2-WIN Connect: Besides lithium, you are also developing geopolymers. Where and how are these used, and why are they an interesting target product for CO2-LiPriSek?

Dr. Kaiser: Geopolymers are CO2-free binders, i.e. their production does not formally require high-temperature activation as with cement. They can be used as building materials in a wide variety of areas. On the one hand, there is the possibility of replacing conventional cements for the construction of houses and roads, on the other hand, heavy metals can also be incorporated into the geopolymers, e.g. in order to immobilise them in the long term. Substituting conventional cement is a key step towards climate neutrality, as the cement industry is one of the largest CO2 emitters. Furthermore, the landfilling of residues is no longer necessary. The COOL process solves environmental problems by producing saleable products, not waste materials. We invert an environmentally relevant cost situation into an environmentally friendly profit situation.

CO2-WIN Connect: How do the two very different products come about, and what does that mean for the selection of project partners or the subsequent market launch?

Prof. Bertau: The products only have nothing to do with each other at first glance. It is more important that you direct the question to this important issue. Until now, it was common to look only at the target product, and then a solution was found for the rest, even if it was landfilling. But those days are over. A frightening number of people still think in this old-fashioned way. But we have to solve problems. Our task is to make the world fit for the future in view of unprecedented population figures, unprecedented CO2 emissions and raw material consumption. A holistic approach is an incredibly simple and elegant way. And if it is designed correctly, it is even an economically successful model. That's why we not only extract the lithium, but also produce a binder from the rest, which replaces the CO2-intensive cement. Such geopolymers have already been successfully tested worldwide.

CO2-WIN Connect:Do you already have an idea of the emission reduction potential of the two products? What kind of CO2 storage potential can be expected from the carbonation of lithium-containing primary and secondary raw materials?

Dr. Kaiser: At this stage of the project, no final assessment can be made. Initial calculations showed that we are more or less CO2-neutral with lithium. For the production of geopolymers, a saving of ~80% compared to conventional cement is already emerging. But we still have a few ideas.

CO2-WIN Connect: When do you expect your product can help to promote electromobility in Germany?

Prof. Bertau: When do you want to get started? We are ready to go.

CO2-WIN Connect: Dr. Kaiser, Prof. Bertau, gladly immediately! Thank you for the interview!


Do you want to learn more about the BMBF-funded Project LiPriSek?

Click here for the project presentation


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