ERES 2017: Six lessons learned

On May 28-31, 2017, the picturesque Greek island of Santorini was the place to be for the European Rare-earth research and innovation community. More than 200 people took part in the 2nd Conference on European Rare Earth Resources, which was a joint organisation by the FP7 EURARE and the FP7 MC-ITN EREAN projects. The conference featured more than 130 papers and speakers, which was substantially more than for the first ERES Conference in Milos in 2014, highlighting the growing rare-earth community in Europe. Here below you can read a personal analysis of the conference: “ERES 2017: Six lessons learned”. Furthermore, you can also find all links to the ERES 2017 Conference Proceedings and the presentations given by the ITN/ETN EREAN, DEMETER and REDMUD PhD students, postdocs and supervisors.

 

ERES 2017: Six lessons learned

  1. The Balance Problem is more relevant than ever

In a multitude of lectures it was made clear that the rare-earth “Balance Problem” is more relevant than ever. The Balance Problem relates to an imbalance between the demands of the market for individual rare earths (REEs) and the natural abundance of REEs in ores, leading to . surpluses (or shortages) of specific REEs. As indicated in previous work (Binnemans & Jones, 2015; Binnemans et al, 2013), the Balance Problem has been a major issue in the (near) past and present. For instance, cerium (Ce) is produced in large quantities by mining REE ores for the production of neodymium (Nd). This has resulted in an oversupply of cerium, which is currently stockpiled. What became clear during ERES 2017 is that the REE Balance Problem is not going to be solved soon. In his keynote lecture “The growing imbalance between production and consumption of individual rare earth elements” Ryan Castilloux (Adamas Intelligence) showed the latest data concerning this issue. His main conclusion was that “over the coming ten years, the rapidly growing demand for NdFeB permanent magnets will drive demand for Nd and Pr to unfathomable new heights, exacerbating the balance problem.” To alleviate this problem, Castilloux called for new REE mines and for “intra-lanthanide substitution”: this is the use of “surplus” REEs (i.e. Ce) in place of a portion of “scarce” REEs (i.e. Nd, Pr) in key end-uses and applications.

balanceProb_ADAMAS

Source: Adamas Intelligence’s “Rare Earth Market Outlook”

 

  1. REE recycling still lurking in the shadows

Strangely enough Castilloux only briefly mentioned the role of REE recycling in the mitigation of the REE Balance Problem (see Binnemans et al, 2013). This is peculiar as the importance of REE recycling (as a possible solution to the Balance Problem) has been well documented (Binnemans & Jones, 2015; Yang et al, 2017), in particular for the recycling of NdFeB permanent magnets. Recycling of these magnets from e-cars, e-bikes, hard disk drives, wind turbines etc. can provide an alternative (and also green) supply of both neodymium and dysprosium, without generating an excess of cerium and lanthanum (as is the case with the primary mining of REE ores). The importance of the Balance Problem has also been highlighted in the final report of the European Rare Earths Competency Network (ERECON).

The peripheral coverage of REE recycling in Castilloux’ lecture/paper is illustrative for the (lack of) weight that is currently given to this field, which is in stark contrast with the attention primary mining of REEs receives. Despite the fact that ERES 2017 featured 41 articles on REE recycling (including two keynotes on REE recycling from the EREAN and REMAGHIC projects), the topic was underrepresented in the crucial opening and closing sessions of the conference. During these sessions, key figures from industry, the European Commission, public bodies and academia discussed the way forward for the EU REE industry. A critical analysis of these Q&A sessions demonstrates that both industry and consultants do not (yet) take REE recycling as a serious partner for primary mining of European REE ores. Two key barriers for widespread REE recycling are the long lag times for key metals to become available for recycling (e.g. NdFeB magnets in wind turbines) and the poor economics (cf. low REE prices in 2017). This should be a “call to arms” for the REE recycling communities: it is of paramount importance to come up with new direct/indirect recycling flowsheets that are relatively simple and limit the use of costly chemicals, thus generating more favourable OPEX and CAPEX features.

 

  1. Primary mining in Europe: the Kvjanefeld project seems to be the winner

Until recently it was generally perceived that Europe does not really own REE-rich ore deposits on home soil and that it would remain dependent on REE-rich countries like China. The FP7 EURARE project set out to investigate the primary REE potential in Europe. As became apparent in the inspiring talk of Kathryn Goodenough of the British Geological Survey, Europe is NOT poor in REE deposits. In fact, geological analyses have shown that the EU has a wide range of primary REE resources, which could easily meet the domestic REE demand. There are several barriers for REE mining in Europe, including the economics (cf. low prices for most REEs anno 2017!), environmental permitting and local protests, radioactivity issues etc.). The stark truth is that anno 2017 there is still no operational REE mine in Europe. This situation might, however, change in the near future. ERES 2017 showed very clearly that punters should put their money on the Kvanefjeld mining project in Greenland, driven by Greenland Minerals and Energy Ltd. In one of the most impressive lectures of the conference, Damien Krebs (Greenland Minerals and Energy) highlighted that this project is coming closer to fruition. Started in 2007 the project is now in the final permitting phase. During this period the company has spent around $80 million in mineral resource and metallurgical evaluation, along with the study of environmental and social impacts.

REE-deposits_EU

REE deposits in Europe

  1. Social license to operate is key

During the closing session of ERES 2017, both Damien Krebs and Mattia Pelegrini (Head of Unit Resource Efficiency and Raw Materials, DG GROW, European Commission) pointed out that the future of REE primary mining in Europe is heavily dependent on obtaining AND maintaining a social license to operate. The present situation of the REE Norra Karr mining project speaks volumes in this context (cf. mining licence issues for Tasman Metals). Terms like greenfield mining and responsible sourcing were all used in the same context and indeed show how important it is to engage with the local and (general) EU community in an open dialogue so as to ensure full buy-in amongst all stakeholders. This is only possible if the mining company can guarantee that its primary mining project uses green mining and processing technologies and, concurrently, provides clear benefits to the communities living in the vicinity of such mines. In densely populated areas, where civil societies are professionally organised, it is essential to come to win-win situations when mining projects are initiated. That’s the only way to go beyond the NIMBY-syndrome (NIMBY = “Not In My Back Yard”). This is very similar as for the attempts to initiate Enhanced Landfill Mining (or on-shore wind energy) projects in Europe.

 

  1. Beyond REEs: watch out for the new CRM figure of the EC

In his opening keynote lecture one the main guests, Mattia Pelegrini (DG GROW), provided an update on the work of the EU Raw Materials Initiative. Pelegrini announced that a third version of the EU criticality figure will be launched soon. Following the reports in 2011 and 2014, the 2017 report will involve a slightly modified approach to calculate the criticality level of a raw materials. The definition of a critical raw material (CRM) still refers to a material “with high risk of a supply disruption and, at the same time, with high economic importance to the EU economy”. Pelegrini clearly mentioned that the figure will be used as a policy tool. As such it will “incentivise the European production of critical raw materials and facilitate the launching of new mining and recycling activities.”

The ERES 2017 participants were hoping to receive a sneak preview of the figure but, unfortunately, Pelegrini declined, which is of course perfectly understandable giving the sensitive character of the final result. We will, therefore, have to wait to see which metals/materials will still be in the quadrant of criticality (e.g. antimony, germanium and which new ones will appear (for instance, cobalt & lithium?). Nevertheless, the chance that the REEs (like neodymium and dysprosium) would disappear altogether from the criticality region of the figure is almost zero.

Pelegrini_ERES_2

Mattia Pelegrini, EC, DG GROW (ERES 2017)

  1. REE research in Europe: Quo Vadis?

During the concluding session there was also an interesting debate about the situation of the REE research community in Europe. Pelegrini (DG GROW) highlighted the importance of the fact that more than 40 PhD students attended (and presented their work at) the ERES 2017 conference. This shows that, in contrast with the situation in 2011, Europe has now trained an “army of REE researchers”. So far the good news. The bad news is that due to the low prices of the REEs anno 2017, industrial interest in the REE value chain has declined again, corroborated by the fact that Solvay (former Rhodia part of the company) closed its flagship REE separation plant in La Rochelle. This implies that at this moment the Silmet plant in Estonia represents the only REE separation capacity in Europe. The situation is now, despite all REE research efforts, more bleak than it was in 2011. Furthermore, Solvay also closed down its lamp phosphor recycling plant because of the poor economics and the decreasing demand for lamp phosphors (for CFL lamps). No other industrial REE recycling activities are currently taking place in Europe, despite a vast amount of developed recycling solutions.

Hence, there is now a clear danger that key REE competences will be (slowly) lost again. This is exactly what happened in the period 1990-2011, during which most of the experts in the European rare-earth industry moved to other fields or retired. As recently indicated in the Policy Brief by Prof. Koen Binnemans (KU Leuven), Europe must draw lessons from the past and must not make the mistake of losing the expertise and knowledge that has been built up during the last few years. Therefore, it is strongly recommended that the EC continues to support project proposals to further develop new technologies in the field of REEs (and other key materials such as antimony, cobalt, lithium etc.) to prepare the European companies for the next rise in the prices of (at least some) rare earths (and other CRMs), which can surely be expected in the near future.

However, as clearly indicated in the closing session by Prof. Bernd Friedrich (RWTH Aachen) it is of paramount importance to avoid redundancy in research. Friedrich pointed out very clearly that too many researchers in Europe are just performing work which has already been tested by other people in the past. A more precise description of the state-of-the-art and a better knowledge of the on-going projects in the field should thus be a condition sine qua non for the funding of any new EU (or national) projects in the future. Pelegrini (DG GROW) acknowledged this comment and made clear that the EC is preparing activities to cluster different EU projects in an attempt to avoid future redundancies. In the EIP Raw Materials Week in November 2017 the REE research community will meet again!

(Author: Peter Tom Jones, Coordinator SIM² KU Leuven)

CLosing_session_ERES

 

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ERES 2017: Downloads

ERES 2017 Conference Proceedings (all papers)

FP7 MC-ITN EREAN Presentations at ERES 2017

  • Yongxiang YANG, REE Recovery from End-of-Life Permanent Magnet Scrap: Challenges and Opportunities in Europe
  • Aida ABBASALIZADEH, Seshadri SEETHARAMAN, Jilt SIETSMA and Yongxiang YANG, Electrochemical extraction of RE from REO using a novel reactive anode
  • Junhua XU, Efficient Recovery and Separation of Co, Nd and Dy from Ternary Solution Using Amorphous Zircomnium Phosphate and Nitric Acid
  • SofĂ­a RIANO, Koen BINNEMANS, Recovery of Neodymium and Dysprosium from NdFeB Magnets using Ionic Liquid Technology
  • Prakash VENKATESAN, Electrochemical recycling of REEs from NdFeB magnet waste
  • Mehmet Ali Recai Ă–NAL, Emir AKTAN, Chenna Rao BORRA, Muxing GUO, Bart BLANPAIN, Tom VAN GERVEN, Recycling of NdFeB Magnets with Nitration-Calcination-Water Leaching
  • Christian JĂ–NSSON, Extraction of Nd-Fe-B magnets from automotive rotors using hydrogen
  • Alexandru LIXANDRU, Iuliana POENARU, Konrad GĂśTH, Roland GAUSS, Oliver GUTFLEISCH, Recycling of Nd-Fe-B scrap permanent magnets via hydrogen processing
  • Iuliana POENARU, Alexandru LIXANDRU, Konrad GĂśTH, Roland GAUSS, Oliver GUTFLEISCH, Light rare-earths substitution in rapidly solidified Nd2Fe14B-based alloys for resource-efficient permanent magnets fabrication
  • Rita SCHULZE, Aida ABBASALIZADEH, Matthias BUCHERT, Estimating environmental impacts associated with a one-step recycling process to extract rare earths from end-of-life Nd-Fe-B magnets
  • Marino GERGORIC, ORGANIC PHASE OPTIMIZATION IN SOLVENT EXTRACTION OF RARE EARTH ELEMENTS FROM NEODYMIUM MAGNET LEACHATES
  • Mikhail S. TYUMENTSEV, Development of polyamide solvent extraction reagents for trivalent lanthanides

H2020 MSCA-ETN DEMETER Presentations at ERES 2017

  • Martina OREFICE, Koen BINNEMANS, Tom VANDER HOOGERSTRAETE, RECYCLING OF NdFeB MAGNETS BY HIGH-TEMPERATURE LEACHING WITH THE IONIC LIQUID [Hbet][Tf2N]
  • Gwendolyn BAILEY, Benjamin SPRECHER, Wim DEWULF, Karel VAN ACKER, Comparative Life Cycle Assessment of NdFeB and SmCo: A Case Study of Permanent Magnet Motors
  • Simona SOBEKOVA FOLTOVA, Sm/Co separation by solvent extraction with ionic liquids

H2020 MSCA-ETN REDMUD Presentations at ERES 2017

  • Chiara BONOMI, Ioanna GIANNAPOULOU, Dimitrios PANIAS, CORRELATION OF SCANDIUM AND TITANIUM DURING LEACHING OF BAUXITE RESIDUE (RED MUD) BY AN IMIDAZOLIUM IONIC LIQUID
  • Bengi YAGMURLU, Carsten DITTRICH, Bernd FRIEDRICH, A Sustainable Alternative for Scandium Concentrate Refining from Redmud Leachates by the Selective Precipitation Method
  • Johannes VIND, Päärn PAISTE, Alan H. Tkaczyk Vicky VASSILIADOU, Dimitrios PANIAS, The behaviour of Scandium in the Bayer process
  • Wenzhong ZHANG, Risto KOIVULA, Risto HARJULA, Ion Exchange Behaviour of Scandium(III) on Crystalline Layered α-Titanium Phosphates: Effect of Sodium Nitrate Addition

H2020 MSCA-ETN REMAGHIC Presentation at ERES 2017

  • Serena SGARIOTO, Bibiana FERRARI, How an Italian SME can recover rare earths from E-Waste

 

0_EREAN_SANTORINI_2017

EREAN Team at ERES 2017 (Closing Meeting)

 

KU Leuven: inside cover Chemical Communications

Daphne Depuydt and Arne Van den Bossche from the group of prof. Koen Binnemans recently published a Communication on “Metal extraction with a short-chain imidazolium nitrate ionic liquid”. As the article was well received by the reviewers and the editorial office of the Chemical Communications journal , it was rewarded with an inside cover. The idea behind the graphical artwork, designed by dr. Joris Roosen, comes from the story of the Old Testament, where Moses splits the sea to guide his people. The cover art shows NaNO3 splitting the sea, with rare earths travelling towards the ionic liquid sea and transition metals moving to the sea filled with water.

Under investigation in the work of Depuydt and Van den Bossche is the 1,3-dihexylimidazolium nitrate ionic liquid-water system which shows upper critical solution temperature (UCST) phase behavior. This means that above the critical temperature, the system becomes a fully homogeneous mixture. The concept of the thermomorphic ionic liquids is not new, yet a novel system with a simple, lowly viscous, short-chain imidazolium ionic liquid was developed. Normally, thermomorphic behavior is exploited in homogeneous liquid-liquid extraction studies. Yet, the addition of salts, in this case sodium nitrate (NaNO3), led to the disappearance of the temperature-dependent miscibility behavior. Instead, a fully biphasic system was found at all temperatures, leading to a hydrophobic ionic liquid system with only half the number of carbons than the usual hydrophobic ionic liquids used in metal extraction studies. The short-chain ionic liquid was used for the separation of rare earths from transition metals.

The article is open access and can be downloaded here. Full reference: Daphne Depuydt, Arne Van den Bossche, Wim Dehaen and Koen Binnemans, Metal extraction with a short-chain imidazolium nitrate ionic liquid, Chemical Communications, 53 (38), 2017, 5271-5274.

Inside Cover Chemical Communications

Capture°COVER

Donwload high resolution pdf cover ChemComm paper here

S. Riaño obtains her PhD on Nd and Dy recovery

On May 12, 2017, Sofía Riaño (KU Leuven, ESR7 in MC-ITN EREAN) successfully defended and obtained her PhD degree at KU Leuven. The topic of Riaño’s PhD dissertation is “Recovery of Neodymium and Dysprosium from NdFeB Magnets using Ionic Liquid Technology”. She obtained this degree in the framework of the EU FP7 Training Network Project, EREAN, which stands for the European Rare Earth (Magnet) Recycling Network. Dr. Riaño was supervised by Prof. Koen Binnemans (KU Leuven). The full text will become available once all research results have been officially published in the peer-reviewed literature. The already published papers can be found below. Dr. Riaño will now continue her research career as a postdoc in the group of Prof. Koen Binnemans where she will work on the PLATIRUS and NEOHIRE projects.

Publications by Sofía Riaño in the framework of this PhD

  1. Riaño, K. Binnemans; Extraction and separation of neodymium and dysprosium from used NdFeB magnets: an application of ionic liquids in solvent extraction towards the recycling of magnets. Green Chemistry 2015, 17, 2931-2942. Download here
  2. Riaño, M. Regadío, K. Binnemans, T. Vander Hoogerstraete; Practical guidelines for best practice on Total Reflection X-ray Fluorescence spectroscopy: Analysis of aqueous solutions. Spectrochimica Acta part B 2016, 24, 109-115. Download here
  3. Regadío, S. Riaño, K. Binnemans, T. Vander Hoogerstraete; Direct analysis of metal ions in solutions with high salt concentrations by Total Reflection X-ray Fluorescence (TXRF). Analytical Chemistry, 2017, 89, 4595-4603.
  4. Riaño, M. Petranikova, B. Onghena, T. Vander Hoogerstraete, D. Banerjee, M. R.StJ. Foreman, C. Ekberg, K. Binnemans; Separation of rare earths and other valuable metals from deep-eutectic solvents: a new alternative for the recycling of used NdFeB magnets. RSC Advances. (submitted and under review).
  5. Riaño, K. Binnemans. “Separation of neodymium and dysprosium using a phosphonium thiocyanate ionic liquid combined with neutral extractants: a process relevant for the recycling of end-of-life NdFeB magnets”. (To be submitted to Hydrometallurgy)
  6. Kontoulis, B. Sprecher, T. Vander Hoogerstraete, S. Riaño, K. Van Acker; “Environmental assessment of newly developed rare earth recycling routes out of end-of-life NdFeB permanent magnets”. (To be submitted to Journal of cleaner production).

 Abstract PhD Sofía Riaño

The rare-earth crisis of 2010 taught the whole world a lesson: the supply of elements that are of high importance for the economy and the development of new technologies (i.e. the critical raw materials) must not rely only on a specific country or region. Investing in primary mining, research for the substitution of rare earth elements in their applications, development of rare-earth recycling schemes and training of highly skilled personnel constituted a set of strategies proposed by Europe to tackle the shortage of rare earths.

The recycling of neodymium-iron-boron (NdFeB) permanent magnets is more interesting from an economic and environmental point of view than the opening of new mines. Additionally, elements high in demand and less abundant, such as dysprosium, can be easily recovered. Other critical and valuable metals can also be recovered as byproducts from the recycling of NdFeB permanent magnets. The recovery and purification of individual rare earths opens the possibility to their reuse in the fabrication of magnets with different compositions for specific applications.

Ionic liquids can be employed as a green alternative to replace the conventional organic phase in solvent extraction processes of rare-earth elements. In this thesis, different approaches involving ionic liquids were developed to recover neodymium, dysprosium and other valuable metals such as cobalt from NdFeB magnets. The extractions were carried out from nitrate and chloride media. The addition of a molecular extractant was also studied and it provided a beneficial lower viscosity of the organic phase and a higher loading capacity in comparison with the pure ionic liquid.

In a new approach, the deep-eutectic solvent choline chloride:lactic acid (molar ratio 1:2) was employed to dissolve the magnets. The solvent extraction process was carried out by contacting the deep-eutectic solvent (more polar phase) with ionic liquids and conventional extractants diluted in toluene (less polar phase).  Iron, boron and cobalt were separated from neodymium and dysprosium using the ionic liquid tricaprylmethylammonium thiocyanate (Aliquat® 336 SCN) diluted in toluene. The separation of neodymium and dysprosium was assessed by using Cyanex® 923 and the feasibility of scaling up this separation process was tested in a mixer settler setup.

Riano_phd_2

 

New Policy Brief on recycling of electric cars

The EU Horizon 2020 projects EREAN and DEMETER have just published a new (joint) Policy Brief on the challenges with respect to the recycling of End-of-Life hybrid and electric vehicles ((H)EVs). The May 2017 Policy Brief is titled: “Processing options and future possibilities for sustainable recycling of Hybrid Electric Vehicles and Internal Combustion Engine vehicles at vehicle recycling sites”.

The motivation for this new Policy Brief is that the new generation of End-of-Life Electric Vehicles (EV) and Hybrid Electric Vehicles (HEV), poses new recycling challenges with respect to the recycling of conventional Internal Combustion Engine vehicles (ICEV). The latter is covered by the End-Of-Life (ELV) Vehicle Directive (Directive 2000/53/EC), which has been a success with 23 member states meeting reuse/recycling targets by 2011 and a significant number exceeding targets. However, the Directive does not yet cater for the first wave of End-of-Life (H)EVs.

Apart from REEs in the magnet motor and in some of the batteries (NiMH type), (H)EVs contain other critical metals such as cobalt (Co), gallium (Ga), indium (In), niobium (Nb), platinum group metals (PGMs), antimony (Sb), tantalum (Ta), and tungsten (W). Cobalt in particular is now being singled out due to the rapidly rising demand for Co-containing Li-ion batteries for not only (H)EVs but also laptops and smartphones.

The problem is that the current ELV recycling practice, which includes shredding, causes random dispersion of the critical metals, especially for metals, which are concentrated within specific process streams but are used in small amounts in the whole vehicle (e.g. neodymium, samarium).

The Policy Brief, which was authored by Prof. Neil Rowson (University of Birmingham) discusses distinct problems and options for the future.

Download the EREAN/DEMETER Policy Brief (May 2017) here.

 

More info about EREAN & DEMETER?

  • The European Rare Earth (Magnet) Recycling Network (EREAN) trains 15 young researchers in the science and technology of rare earths, with emphasis on the recycling of these elements from neodymium-iron-boron permanent magnets. Website EREAN.
  • DEMETER is the European Training Network for the Design and Recycling of Rare-Earth Permanent Magnet Motors and Generators in Hybrid and Full Electric Vehicles. DEMETER concurrently develops (1) innovative,
    environmentally-friendly direct and indirect recycling strategies for the permanent magnets in the motors and generators of (H)EVs that are currently already on the market and (2) Design-for-Reuse solutions for motors and generators in the (H)EVs of the future. Website DEMETER.

Free Mockups Vol 2 - 2-2

J. Roosen obtains PhD on critical metal recovery

roosenOn May 8, 2017, Joris Roosen (SIM² KU Leuven & LIC) successfully defended and obtained his PhD degree at KU Leuven. The topic of Roosen’s PhD dissertation is “RECOVERY OF CRITICAL METALS FROM DILUTE AQUEOUS WASTE STREAMS BY ADSORPTION ON FUNCTIONALIZED BIOPOLYMERS”. This work was funded by VITO, the Research Foundation Flanders (FWO, PhD fellowship) and KU Leuven. The full text will become available once all research results have been officially published in the peer-reviewed literature. The already published papers can be found below. Supervisors for Dr. Roosen were Prof. Koen Binnemans (KU Leuven) and Dr. Steven Mullens (VITO). Dr. Roosen will now continue his research career as a postdoc in the Group of Prof. Koen Binnemans (KU Leuven) where he will work on the SIM Get-A-Met project.

Publications by Joris Roosen in the framework of this PhD

  • Roosen, S. Mullens, K. Binnemans, “Multifunctional alginate-sulfonate silica sphere-shaped adsorbent particles for the recovery of indium(III) from secondary resources”, manuscript submitted and under review.
  • Roosen, S. Mullens, K. Binnemans, “Chemical immobilization of 8-hydroxyquinoline and 8-hydroxyquinaldine on chitosan-silica adsorbent materials for the selective recovery of gallium from Bayer liquor”, manuscript under revision.
  • Kim, J. Roosen, L. Horckmans, J. Spooren, K. Broos, K. Binnemans, K.C. Vrancken, M. Quaghebeur, “Process development for hydrometallurgical recovery of valuable metals from sulfide-rich residue generated in a secondary lead smelter”, Hydrometallurgy, 169, 2017, 589-598.
  • Roosen, S. Van Roosendael, C. R. Borra, T. Van Gerven, S. Mullens, K. Binnemans, “Recovery of scandium from leachates of Greek bauxite residue by adsorption on functionalized chitosan–silica hybrid materials”, Green Chemistry, 18, 2016, 2005-2013. Download here.
  • Roosen, J. Pype, K. Binnemans, S. Mullens, “Shaping of Alginate–Silica Hybrid Materials into Microspheres through Vibrating-Nozzle Technology and Their Use for the Recovery of Neodymium from Aqueous Solutions”, Industrial & Engineering Chemistry Research, 2015, 54, 12836-12846. Download here.
  • Roosen, J. Spooren, K. Binnemans, “Adsorption performance of functionalized chitosan-silica hybrid materials toward rare earths”, Journal of Materials Chemistry A, 2014, 2, 19415-19426. Download here
  • Roosen, K. Binnemans, “Adsorption and chromatographic separation of rare earths with EDTA- and DTPA-functionalized chitosan biopolymers”, Journal of Materials Chemistry A, 2014, 2, 1530-1540.

Public abstract PhD Joris Roosen

A circular economy aims at a more efficient use of resources by closing the materials loop and reusing “waste” as a secondary raw materials source. This can be challenging and demands for new methods to be explored. For instance, in the case of dilute waste streams from industrial processes, the challenge is to efficiently recover very low concentrations of valuable metals from huge volumes of waste water. Adsorption is considered to be the key technology to do so. During this PhD, the biopolymers chitosan and alginate were examined for the adsorption of critical metals from dilute aqueous solutions. Biopolymers are biologically renewable, which makes them easily available, in any quantity and at low cost. They have interesting physicochemical characteristics and are characterized by an abundant availability of functional groups. These provide biopolymers with a high adsorption capacity and can be used as well to immobilize chelating agents on the adsorbent matrix, thus increasing the selectivity for specifically targeted metal ions. Chitosan-silica hybrid materials were functionalized with the organic ligands EDTA and DTPA for the adsorption of lanthanides, EGTA for the selective recovery of scandium from leachates of Greek bauxite residue and 8-hydroxyquinaldine for the separation of gallium from aluminium out of spent Bayer liquor. In addition to chemical modifications, the adsorption performance was further improved through the morphology of the adsorbent materials. With the aim to develop materials that are industrially applicable for a broad range of process configurations, porous microspheres were created from alginate by the vibrating-nozzle technology and the incorporation of a stable silica matrix was investigated. Multifunctional alginate-sulfonate-silica spheres were created and studied for the selective recovery of indium from a simulated leachate of a zinc refinery residue. The functionalized biopolymer materials synthesized during this PhD have proven to be particularly suitable for the selective recovery and separation of critical metals from dilute aqueous waste streams. In time, this knowledge should allow a more efficient use of our resources in the transition towards a more sustainable future.