Chair of Separation Science and Technology

VALuable METals through innovative HYDROmetallurgy

The GeMMe “Mineral Processing and Recycling” group at the University of Liege, Belgium is looking to engage a suitable candidate to be in charge of a project described below (pending on negotiation/approval from the Walloon administration within the BEWARE-ACADEMIA call).

More information.

Master thesis: Multiscale study and modelling of emulsions properties relevant for liquid-liquid extraction, adaptation of breakup and coalescence kernels to industrial processes

Pulse columns are commonly used in extraction processes, particularly for the treatment of spent nuclear fuel. They have been the subject of many studies, at CEA and in many research teams in France and abroad. However, the needs inherent in new societal challenges (energy transition and variability of fuel to be treated; extraction and recycling of rare earths and critical metals, etc.) now require the development of models to predict the performance of these devices in a wider range of operating conditions. The systematic use of large-scale experiments being excluded today a phenomenological approach, relying largely on modeling and numerical simulation, has gradually been implemented.

The proposed subject, coupling fluid mechanics, physical chemistry of interfaces and instrumentation, is part of this approach.

In a first thesis, the turbulent properties of the pulsed column flow were studied, and a model for the simulation of coupled flow and droplet population balance (coupling CFD and PBE) was developed under ANSYS-Fluent. During this work, the models of coalescence and breakage of the literature were analyzed and the most relevant one was chosen to describe the emulsification of water in oil in a pulsed laboratory column, and its parameters were experimentally determined.

One of the first objectives of the new thesis is to propose model based going to on a better description of the flow properties and their coupling with the interfacial dynamics. The purpose of this work is indeed to derive a more phenomenological modeling (kernels) for coalescence and breakup, which will account for specific features of liquid-liquid extraction devices. We will focus particularly on the effect of the viscosity of the continuous phase (existing models usually deal with "oil in water" emulsions), of the mass transfer between the two phases (Marangoni effect), and on the influence of walls wettability (contact angle).

Wettability effect has already been the subject of experimental studies at the CEA. At column scale, the comparison of the emulsions produced with "fully", "partially" and "non" wetting walls and packing elements allowed to propose an empirical model including a wetting law in the population balance.

Similarly, the influence of mass transfer was observed and assessed, however not yet modelled. This is among the on-going researches at TU Kaiserslautern.

It is therefore proposed to revisit these studies in view of recent advances in digital and experimental means. Preference will be given in this framework an experimental approach, based on liquid-liquid systems perfectly characterized and scales and hydrodynamic properties on different devices: isolated drops, diluted emulsion stirred reactor and emulsion pulsed column:

-  Single drop experiments, coupled with high speed observations, will allow extending the classical breakage and coalescence models that are based on energy considerations, to a more dynamic analysis of the phenomena and forces acting on the drop. A statistical study by varying the properties of both liquid phases, and including mass transfer, will enhance the intrinsic models of rupture and coalescence.

-  Studies in stirred reactor with in-situ measurements of the droplet size distribution, will allow transposing the features deduced from isolated drops, with and without mass transfer, to dilute dispersion, within a range of turbulent dissipation, representative of the epsilon level in a pulsed column

-  Finally, pulsed column experiments, also with in-situ monitoring of the drop size distribution, will allow investigating near-industrial configurations and addressing the key uncertainties, particularly as regards the influence walls wettability.

The master thesis, jointly supervised between the University Claude Bernard Lyon 1 (Dr. Nida Shaibat Othman), the Technological University of Kaiserslautern (Pr. H.-J. Bart), ant Polito Turin (Pr. D. Marchisio) will be based in CEA Marcoule in France, near Avignon (Dr. S. Charton).

More details, please contact:         

Phone Bart:         +49(0)631-205-2414                    


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