New PhD on REE recovery from bauxite residue

On July 2nd, 2018, Dženita Avdibegović obtained her PhD degree in Chemistry. She successfully defended her PhD thesis entitled ‘Recovery of rare earths from bauxite residue leachates by functionalised sorbents‘. (Leuven, 02/08/2018)

The research was supervised by Prof. Koen Binnemans (promotor) and Dr. Mercedes Regadio (co-promotor). Dr. Avdibegović obtained her degree in the framework of the European Training Network for Zero-Waste Valorisation of Bauxite Residue (REDMUD). A list of the peer-reviewed papers published in the framework of her PhD can be found below. The full text of the thesis will become available once all research results have been officially published in the peer-reviewed literature. Dr. Avdibegović will now continue her research career as a postdoc in the group of Prof. Koen Binnemans, where she will work on the separation of REE ions by magneto-chromatography.

Abstract

Bauxite residue, better known as red mud, is a waste product of the alumina industry, but with many unexploited values. The estimated inventory of bauxite residue in operating and closed alumina refineries reaches the value of several billion of tonnes. Stockpiling of huge amounts of residue can create environmental problems. Bauxite residue comprises iron, aluminium, titanium, sodium and even more interestingly, valuable rare-earth elements (REEs). Although a lot of research has been done on bauxite residue valorisation, to date there are no large-scale applications of bauxite residue yet. The REEs, and scandium in particular, are generally more enriched in residues originating from karst bauxites. Interestingly, bauxites found in the southern region of Europe belong to the group of karst bauxites. Europe currently has no operating REE mine, although these elements are getting an increasing role as materials for the transition to cleaner energy and the production of high-tech devices.

In this PhD thesis sorbents were synthesised and investigated for the recovery of REEs from bauxite residue leachates. The leachates can be prepared by direct leaching of bauxite residue with mineral acids, or as a processing step after recovery of other valuable metals. The leachates typically comprise low concentrations of REEs, whereas base elements like iron or aluminium are concentrated. Liquid-solid extraction is a suitable method for recovery of elements from dilute streams. This process requires sorbents selective for elements of interest. Supported ionic liquid phases (SILPs) and crystalline zirconium-phosphate (ι-ZrP) were synthesised, characterised and examined for the REEs recovery and separation from other element present in bauxite residue leachates. Moreover, hybrid materials prepared by grafting of short n-alkyl chains (ethyl, n-propyl and n-butyl) to titanium(IV) phosphate functionalised mesoporous MCM-41 silica were tested for mutual separation of REEs.

Publications by Dženita Avdibegović in the framework of her PhD

  1. Avdibegović D., Regadío M., Binnemans K. (2018). Efficient separation of rare earths recovered by a supported ionic liquid from bauxite residue leachate, RSC Advances, 8, 11886–11893.
  2. Avdibegović , Regadío M., Rivera R.M., Onoughene G., Van Gerven T., Binnemans K., Purification of low concentration of rare earths from high concentration impurities in leach liquor of bauxite residue slag by a supported ionic liquid phase. In: Y. Pontikes (ed) Proceedings of the 2nd International Bauxite Residue Valorisation and Best Practices Conference. 7-10 May 2018, Athens, Greece, 381-386.
  3. Avdibegović D., Regadío M., Binnemans K. (2017). Recovery of scandium(III) from diluted aqueous solutions by a supported ionic liquid phase (SILP). RSC Advances, 7, 49664-49674.
  4. Zhang W., Avdibegović, D., Koivula R., Hatanpaa T., Hietala S., Regadío M., Binnemans K., Harjula R. (2017). Titanium alkylphosphate functionalised mesoporous silica for enhanced uptake of rare-earth ions. Journal of Materials Chemistry A, 5(45), 23805-23814. Joint first author with Wenzhong Zhang.
  5. Avdibegović, D., Yagmurlu, B., Dittrich, C., Regadío, M., Friedrich, B., Binnemans, B., Combined multi-step precipitation and supported ionic liquid phase chromatography for the separation of rare earths from the base elements in bauxite residue leachates. Manuscript under revision. Joint first author with Bengi Yagmurlu.
  6. Avdibegović, D., Zhang, W., Xu, J., Regadío, M., Koivula, R., Binnemans, K. Selective ion-exchange separation of Sc(III) over Fe(III) by crystalline α-zirconium phosphate platelets from bauxite residue leachates. Manuscript under preparation. Joint first author with Wenzhong Zhang.

MSA: a green solvent for REE recovery

Within the EU H2020 REMAGHIC project, SIM² KU Leuven developed a process to recover rare earths from lamp phosphor waste by dissolution in concentrated methanesulphonic acid (MSA), a green solvent known for its characteristics of thermal stability, low toxicity and biodegradability. (Leuven, 2/8/2018)

Besides yttrium and europium, lamp phosphor waste represents an interesting source of the valuable rare earth terbium, which is present in the green phosphors LaPO4:Ce3+,Tb3+ (LAP), CeMgAl11O19:Tb3+ (CAT) and (Ce,Gd)MgB5O10:Tb3+ (CBT). The current treatment technologies for terbium recovery from lamp phosphor waste involve long leaching times and harsh conditions, due to the difficulty of dissolving rare earth phosphates.

Graphical Abstract MSA paper RSC AdvancesIn this paper we present a milder approach for dissolving the LAP phosphor, by making use of concentrated methanesulphonic acid (MSA, CH3SO3H) as leaching agent. MSA is labelled as green solvent: it is biodegradable, it has a high boiling point and it is thermally stable so that it can be used at temperatures up to 200 °C. This first leaching step with concentrated MSA is an example of ‘solvometallurgical leaching’ or ‘solvent leaching’. Solvometallurgy is a new branch of metallurgy which is receiving increasing attention among the scientific community. Solvometallurgical processes are based on the use of solvents other than water and normally show some advantages compared to the classical hydrometallurgical process, such as higher selectivity and the reduction of the waste streams to be processed afterwards. In our process the valuable rare earth terbium was quantitatively leached from a synthetic LAP phosphor in only 1 h.

When the process was applied on a real lamp phosphor residue (obtained after leaching the lamp powder with H2SO4), about 74% terbium was dissolved. This is due to the fact that in the real waste not all the green phosphors is LAP, but some of the terbium is in the phosphors CAT and CBT, which cannot be dissolved by concentrated MSA. After leaching, rare earths are recovered though a separation step performed by solvent extraction with di-(2-ethylhexyl)phosphoric acid (D2EHPA). By contacting the diluted leachate with 70% D2EHPA in xylene, terbium was selectively extracted over lanthanum and cerium and afterwards stripped by an oxalic acid solution. The raffinate coming from this first solvent extraction step was subjected, after further dilution, to a second solvent extraction step aimed at extracting La and Ce, which were then stripped with oxalic acid, as in the case of terbium. The obtained rare earth oxalates were finally calcined in order to get the corresponding oxides (Tb4O7, CeO2, La2O3). These mixed REE oxides can be further purified by solvent extraction in order to remove the co-extracted yttrium, europium and gadolinium, which are inevitably dissolved in the selected leaching agent.

Full reference paper

Lukas Gijsemans, Federica Forte, Bieke Onghena, Koen Binnemans, Recovery of rare earths from the green lamp phosphor LaPO4:Ce3+,Tb3+ (LAP) by dissolution in concentrated methanesulphonic acid, RSC Advances, 2018, 8, 26349-26355, DOI: 10.1039/C8RA04532A

Acknowledgements

This work has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under Grant Agreement No. 680629 (REMAGHIC: New Recovery
Processes to produce Rare Earth-Magnesium Alloys of High Performance and Low Cost) (project website: http://www.remaghic-project.eu). The authors acknowledge Relight
Srl (Rho, Italy) for providing the residue.

Bio first author

Lukas Gijsemans imageLukas Gijsemans was born in 1993 in Belgium and graduated as a master in chemistry in 2016. He immediately started working with Prof. Koen Binnemans at the Lab for Inorganic Chemistry (LIC) at the KU Leuven as a research associate. The main focus of his research is solvometallurgical leaching and solvent extraction of industrial waste.

Call for applicants: 15 PhD positions in CHARMING

The EU Horizon 2020 MSCA-ETN CHARMING consortium is looking for a dynamic team of 15 bright and enthusiastic PhD students. The call for applicants is now officially open. PhD candidates need to apply on-line through the CHARMING application tool. The deadline for on-line applications is October 15, 2018. 

On-line Recruitment Procedure (APPLY HERE)

All applications proceed through the on-line recruitment portal on the www.charming-etn.eu website. Candidates apply electronically for one to maximum three positions and indicate their preference. Candidates provide all requested information including a detailed CV (Europass format obligatory) and motivation letter. During the registration, applicants will need to prove that they are eligible (cf. ESR definition, mobility criteria, and English language proficiency). The deadline for the on-line registration is 15 October 2018. The CHARMING Recruitment Committee selects between 20 and maximum 30 candidates for the Recruitment Event which will take place in Leuven, Belgium (13 November 2018). The selected candidates provide a 20 minute presentation and are interviewed by the Recruitment Committee. Candidates will be given a domain-relevant peer-reviewed paper (prior to the recruitment event) by their prioritised Supervisor and will be asked questions about this paper during the interview to check if the candidate has the right background/profile for the ESR position. Prior to the recruitment event, skype interviews between the Supervisors and the candidates are recommended, along with on-line personality tests.

Key dates

• 30-6-2018: Launch 15 ESR positions

• 15-10-2018: Deadline for on-line application

• 30-10-2018: Circulation list “preselected candidates”

• 13-11-2018: CHARMING Recruitment Event

• 20-11-2018: Circulation list “recruited CHARMING ESRs”.

• 12-2018 – 04-2019: Targeted starting date for ESR contracts

Full details about 15 positions and procedure

Download here

General coordinator for ETN CHARMING:
Prof. Tom Van Gerven (KU Leuven)
tom.vangerven@kuleuven.be
+32 (0) 16 32 23 42

General contact person for ETN CHARMING:
Mrs. Rabab Nasser (KU Leuven)
rabab.nasser@kuleuven.be
+32 (0) 495 59 38 21

New Phd on The use of hydrogen to extract NdFeB and REEs from Assemblies

Christian JĂśnsson (2)

On June 7th 2018, Christian Jönsson successfully defended his Ph.D. thesis at the University of Birmingham, UK. The work was part of the EU FP7 MC-ITN project EREAN, short for ”European Rare Earth (Magnet) Recycling Network”, and was supervised by Professor Allan Walton.
The title of the thesis is ”The use of hydrogen to extract NdFeB and REEs from Assemblies”, and it investigates:
• Potential WEEE sources for NdFeB recycling. Working together with two other EREAN researchers, a wide range of products were dismantled and assessed at STENA’s recycling plant in Halmstad, Sweden. It was concluded that loudspeakers from flat screen TVs are the best WEEE NdFeB recycling candidate after HDDs.
• How hydrogen can be used as an extraction tool of NdFeB from assemblies. This has previously been demonstrated on HDDs, and this thesis showed that the same principles can be used on automotive rotor magnets. However, the rotor magnets react much slower due partly to a higher Dy content, which makes it unfeasible to operate at atmospheric pressure.
• How hydrogen can be used in the separation of REEs from the NdFeB alloy.
1) A range of hydrogen treatments were applied to the as-extracted powder to find the optimal version for oxidative roasting. It was found to be the as-extracted HD powder due to its highly reactive oxidation pathway, the NdH2.7 grain boundaries.
2) The disproportionation reaction (>650 C in hydrogen) dissociates Nd2Fe14B into its elemental constituents on a nano-scale and is the first part of the HDDR process where the hydrogen is immediately removed to recombine the elements into fine Nd2Fe14B grains.
By doing the opposite, holding the temperature high in hydrogen for extended hold times, the microstructure coarsened and formed large pools of NdH2. This is believed to open up for the physical separation of REEs from NdFeB, a whole new recycling concept!

Umicore vacancy: Innovation Project Manager

For its Group Research & Development located in Olen (Belgium), Umicore is currently looking for an Innovation Project Manager. This is a final call for candidates who hold a PhD or Master with more than 5 years of relevant experience in chemical, metallurgical or environmental engineering. (Leuven, June 2018)

Job Description

Do you have a strong background in recycling and extraction, in processes and technologies? Are you passionate about learning and sharing knowledge, and about generating new ideas and insights to advance and accelerate research initiatives? Do you want to work on research projects with a longer time horizon? Are you a strong networker and communicator, connecting internally with a broad network of colleagues, and externally with Umicore’s network of university, research institute and industry partners for open innovation? For its Group Research & Development located in Olen (Belgium), Umicore is currently looking for an: Innovation Project Manager

 Responsibilities

  • You manage innovative projects with a longer time horizon in the field of recycling and extraction.
  • You contribute to and extend our external network for collaborative research, in search for new opportunities.
  • You actively develop your expertise, and share it within the organization. Moreover, you facilitate the connection between outside knowledge and developments, and the relevant colleagues inside Umicore.
  • You interact with internal and external customers and stakeholders.
  • You are accountable for the results, timing and budget within your responsibilities.
  • You take responsibility for environmental, health and safety aspects.

 Profile

 You hold a PhD or Master with more than 5 years of relevant experience in chemical, metallurgical or environmental engineering or an equivalent area.

  • You are creative. You like exploring and are open minded towards new ideas and concepts. You stimulate your own and others’ creativity and innovation.
  • You are a strong communicator, verbally and written, with excellent networking skills, able to proactively build functional relations inside and outside the company.
  • You have good analytical skills, able to assess and summarize (numerical) information and share knowledge and expertise with others.
  • Your entrepreneurial mindset is able to evaluate new ideas and their technical and economic feasibility.
  • You are skilled in organizing and planning. You are result-oriented.
  • You are fluent in English both written and orally. You speak Dutch or you are prepared to master it rapidly. Knowledge of French or German is a plus.
  • You are willing to travel abroad.

Application closes on 8th of June 2018. Apply here. Umicore offers several other new positions which are worth cheking out.