Hydro- and solvometallurgical processes

General theme: Innovative, efficient hydrometallurgical and solvometallurgical processes are developed for the recovery of base metals (Cu, Zn, Ni) and critical metals (REEs, PGMs, Ge, In, Sb, Ga, Co, Ta) from End-of-Life consumer goods, industrial process residues and low-grade ores. The recovery of the metals is part of larger flow sheets, which target near-zero-waste valorisation of the metal-containing residues.

Flagship Topics:

Solvometallurgical leaching and preconcentration of metals.

In solvometallurgical processes the aqueous phase of hydrometallurgical processes is partly or completely replaced by an organic solvent. One approach is “solvent leaching” in which the leaching is performed with a complexing agent (acting as an extractant) in an organic solvent. Lixiviants are often more reactive in organic solvents than in water. A second solvometallurgical method is “slurry solvent extraction”. Here, the finely crushed ore is wetted by a small volume of acid solution, and this slurry is contacted with a water-immiscible organic phase, containing an extractant. This approach is similar to conventional solvent extraction, but the volume of the aqueous phase is largely reduced

Solvent extraction for separation and purification of metals

Undiluted ionic liquids are used in solvent extraction processes for the separation of mixtures of rare earths and for the purification of other metals. Undiluted ionic liquids offer in solvent extraction the advantage of a very high extractant concentration, allowing for high metal loadings in the organic phase. Additionally, non-aqueous solvent extraction processes are developed. In non-aqueous solvent extraction, the metals are distributed between two non-miscible organic phases (a less polar and more polar phase). Because the solvation of metal ions in polar organic solvents is different from that in water, other selectivities can be achieved in solvent extraction processes. The solvent extraction experiments are carried out in a small lab scale as well as in mini-pilot scale with mixer-settlers.

Metal recovery from dilute aqueous waste streams

Metal ions are recovered from dilute aqueous waste streams and leachates by means of highly selective adsorbents. Two types of adsorbents are being considered: (1) adsorbents made by functionalisation of biopolymers such as chitosan or alginate, and (2) supported ionic liquid phases (SILPs). In SILPS an ionic liquid is immobilised on a solid support. SILP technology is very flexible, because both the type of ionic liquid and the solid support can be optimised independently. By the use of functionalised ionic liquids, very selective adsorbents can be obtained

Design of extractants and solvent formulation

New extractants are designed, synthesised and characterised. Traditional extractants are prepared in high purity for fundamental studies and at larger scale for mixer-settler studies. By combining 2 or 3 different extractants, synergistic solvent mixtures can be obtained with extraction behaviour that is different from that of the individual extractants. Special attention is paid to the active role of diluents in solvent extraction processes.

Mechanistic and speciation studies

Different spectroscopic techniques (e.g. UV-VIS-NIR spectroscopy, NMR, FTIR, Raman, EXAFS, see also RL1) are used to determine what types of metal complexes are formed in aqueous and organic solutions under different conditions. The speciation studies give information on the composition (stoichiometry) and structure of metal complexes in solution: the number and type of ligands coordinated to the metal ion, the molecular mass (and the degree of oligomerisation), the number of coordinated water molecules (hydration number). Knowledge of the speciation is essential for modelling the extraction process at a molecular level and as input for mechanistic studies of solvent extraction processes. Special emphasis is paid to speciation in highly concentrated solutions, with high metal concentrations and/or high salt concentrations. Understanding of the mechanism of solvent extraction at a molecular level is essential for the development of more efficient separation processes.

The Team

The leading members in this research line are:

Prof. Koen Binnemans
Prof. Koen BinnemansKoen Binnemans
Prof. Koen Binnemans (RL Leader) is a world-leading expert in the chemistry of REEs and the environmentally-friendly use of ILs in solvent extraction and critical metal recovery. Author of more than 200 papers on REEs (320 papers in total) with a h-index of 48 (54 according to Google Scholar) and over 10000 citations. General coordinator of EU FP7 MC-ITN EREAN, H2020 MSCA-ETNs REDMUD and DEMETER, and Steering Committee Member of ERECON (DG Enterprise and Industry). Vice-chair of the European Rare-Earth and Actinide Society (ERES).
Prof. Tom Van Gerven
Prof. Tom Van Gerven
Prof. Tom Van Gerven has a background in chemical engineering and is a specialist in process intensification using localised energy and alternative energy forms (ultrasound, light, microwaves etc.). Prof. Van Gerven’s role in RARE³ is the application of process intensification techniques to the leaching of low grade ores and industrial process residues and to the solvent extraction. This includes ultrasound- and microwave-assisted leaching, light-assisted separations and the use of microflow reactors for solvent extraction.
Dr. Lieven Machiels
Dr. Lieven Machiels
Dr. Lieven Machiels is a geologist performing research in the area of Enhanced Landfill Mining, plasma processing and slag valorisation and is highly active in the industrial implementation of inorganic polymer based building products in Flanders.
Dr. Sofia Riano
Dr. Sofia Riano
Dr. Bieke Onghena
Dr. Bieke Onghena
Prof. Bart Blanpain
Prof. Bart Blanpain
Prof. Bart Blanpain (RL Leader) leads the HiTemp Group, has more than 20 years of experience in the field of pyrometallurgy including ferrous and non-ferrous metallurgy and slag processing. Bart Blanpain’s Group has an excellent track record in (mainly) strategic basic and applied science projects involving slag/residue valorisation, refractory wear, urban/landfill mining and novel/optimised metallurgical flow sheets (incl. projects with Aperam, ArcelorMittal Sidmar, Umicore, MetalloChimique, Campine, Group Machiels etc.
Prof. Jan Fransaer
Prof. Jan Fransaer
Prof. Jan Fransaer is a full professor of chemistry (Department of Materials Engineering). His research group has a tradition in experimental & computational electrochemistry. More than 100 peer reviewed publications and 11 patents in this field. He was involved in 7 EU projects (2 as coordinator) on electrodeposition. The group made significant contributions to the practical and theoretical understanding of the electrodeposition of particles together with metals, and was one of the first to study this process using non-aqueous electrolytes.
Prof. Wim Dehaen
Prof. Wim Dehaen
Prof. Georgios Stefanidis
Prof. Georgios Stefanidis
Prof. Georgios Stefanidis is an associate professor at the Faculty of Engineering Science and head of the Subdivision Alternative Energies. His research topics include process intensification, chemical reactor engineering and alternative energy forms and transfer mechanisms (microwaves, plasma).
Prof. Jo Van Caneghem
Prof. Jo Van Caneghem