The goal of this research is to improve an extractive metallurgy process based
on solvent extraction. This process should fit the exploitation of small local
copper-rich deposits. In these conditions, the plant has to be as compact as
possible in order to be easily transported from one location to a subsequent
one. Improved extraction kinetics could ensure a high throughput of the
plant despite its compactness. In addition, the extraction reagent should
not be damaging for the environnement. On this basis, we propose to use
ultrasound-assisted solvent extraction. The main idea is to increase the
extraction kinetics by forming an emulsion in place of a dispersion thanks to
the intense cavitation produced by ultrasound. The benefit of this method
is to improve the copper extraction kinetics by increasing the interfacial
surface area and decreasing the width of the diffusion layer. We studied the
implementation of an highly branched decanoic acid (known as Versatic-
10®acid) as a copper extraction reagent dispersed in kerosene.
Emulsification is monitored through the Sauter diameter of the organic
phase droplets in aqueous phase. This diameter is measured during pulsed
and continuous ultrasound irradiation via a static light scattering technique.
The phenomenon of emulsification of our system by ultrasound is effective,
and the emulsification process carried out in the pulsed ultrasound mode is
at least as efficient as the emulsification obtained under continuous mode.
No improvement of emulsification is observed beyond a threshold time of
the ultrasound impulse. This may be attributed to a competition between
disruption and coalescence. The use of mechanical stirring combined with
pulsed ultrasound allows to control the droplet size distribution.
In presence of ultrasound, the extraction kinetics of Versatic-10 acid is
multiplied by a factor ten, and therefore reached a value similar to the kinetics
observed without ultrasound with an industrial extractant such as
LIX-860I®(Cognis). Extraction kinetics measurements are carried out by
monitoring the copper ion concentration in the aqueous phase with an electrochemical
cell.
We conclude that ultrasound-assisted emulsification can be implemented
under certain conditions. Emulsification is a first step, and the following
destabilization step has to be studied. The device using ultrasound-assisted
emulsification should be followed by an efficient settling-coalescing device. A
possible solution would be to promote emulsion destabilization by increasing
the ionic strength with an addition of MgSO4, a salt that is not extracted
by the extraction reagent in the considered range of pH.
| Identifer | oai:union.ndltd.org:BICfB/oai:ulb.ac.be:ETDULB:ULBetd-03282010-200454 |
| Date | 25 March 2010 |
| Creators | Duhayon, Christophe C. |
| Contributors | Delplancke-Ogletree, Marie-Paule, Delplancke, Jean-Luc, Segers, Luc, Bartik, Kristin, Olivier, Marie-Georges, Frenay, Jean |
| Publisher | Universite Libre de Bruxelles |
| Source Sets | Bibliothèque interuniversitaire de la Communauté française de Belgique |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://theses.ulb.ac.be/ETD-db/collection/available/ULBetd-03282010-200454/ |
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