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Thèse de doctorat/ PhD Thesis Citation APA:

Duhayon, C. (2010). Copper solvent extraction by ultrasound-assisted emulsification (Unpublished doctoral dissertation). Université libre de Bruxelles, Faculté des sciences appliquées – Matériaux, Bruxelles.

Disponible à / Available at permalink : https://dipot.ulb.ac.be/dspace/bitstream/2013/210155/5/64ae57f1-bb9b-4642-96f8-fd349397e8fb.txt

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D 03740

uiniversité libre de

B

ruxelles

Faculté des Sciences Appliquées Matières & Matériaux Groupe Chimie Industrielle

Matières

mm

&

Matériaux

Copper solvent extraction by

ultrasound-assisted émulsification

Dissertation originale présentée par Christophe DUHAYON

en vue de l’obtention du grade de Dr'-""’

X

Promoteurs

Prof. M-P. Delplancke-Ogletree (ULB)

Prof. J-L. Delplancke

Année académique 2009-2010

(3)

À mes parents.

(4)

Celui qui commande se déprave, celui qui obéit se rapetisse. La morale qui naît de la hiérarchie sociale est forcément corrompue.

Élisée Reclus.

Il

Avoir honte de son immoralité : c’est un degré sur l’échelle au bout de laquelle on a honte aussi de sa moralité.

Friedrich Nietzsche.

Plus la vérité que tu veux enseigner est abstraite, plus il te faut y amener les sens.

Friedrich Nietzsche.

Ainsi as-tu fait au vase à Soissons !

Clovis 1er.

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111 Abstract

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 subséquent 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 émulsion 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 implémentation 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 continuons ultrasound irradiation via a static light scattering technique.

The phenomenon of émulsification of our System by ultrasound is effective, and the émulsification process carried out in the pulsed ultrasound mode is at least as efficient as the émulsification obtained under continuons mode.

No improvement of émulsification is observed beyond a threshold time of the ultrasound impulse. This may be attributed to a compétition 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 ki­

netics 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 elec- trochemical cell.

We conclude that ultrasound-assisted émulsification 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

émulsification should be followed by an efficient settling-coalescing device. A

possible solution would be to promote émulsion destabilization by increasing

the ionic strength with an addition of MgSOi, a sait that is not extracted

by the extraction reagent in the considered range of pH.

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Acknowledgements

I would like to thank the following persons (in a random order):

Imane

Marie-Paule Delplancke-Ogletree Jean-Luc Delplancke

Mes parents, Ann & Christian Ma famille, pour leur soutien Thibaut Wattiez (&: Alexandra)

Vanessa Gutierrez Morân (& Sébastien Ferez) aka. Pilar aka. Vaness.

On va boire un coup après la défense publique ? Paraît que c’est gra­

tuit!

Nathalie Nayer &: Fabrizio Buttafuoco Jean-Sébastien Billet aka. JSB

Luc Segers

Véronique Halloin Benoît Haut Kristin Bartik

Stefan Van Vaerenbergh Frank Dubois

Olivier Monnom Antonio Pagliero

Samuel Fruchter aka. Sam Colin Aughet aka. Colin le Lapin Gilles Wallaert aka. Gillou

Valérie Spaeth aka. ma blonde (celle de Vanessa, pour être précis).

Shaïn Ismail aka Maître-Chat

Aurore De Boom aka. Madame Boum-boum

iv

(7)

V

Enrico Tam aka. Il dottore Nico Claessens

Eric Leeuwerck On se souviendra longtemps de l’escalade du portail du cimetière d’Ixelles (de nuit, et éméchés) afin d’aller d’honorer la tombe d’Elisée Reclus...

Aimée, Anne, Elisabeth, Fikri, Gauthier, Georges, Jacques &; Julien

Mimouna & Yves

ma p’tite soeur Hélène & Nico Eliane & Marie-Jeanne

Henri & Robert

Pziscal Brochette Sa connaissance des émulsions n’a pas de prix.

Marion Sausse Michel Pierobon Mes conseillers personnels en ce qui concerne

Nicolas Bastin & sa DTR-X Curieusement, il a commencé par m’expliquer ce qu’il ne fallait pas faire en moto..

Yamaha La sécu rembourse les anti-dépresseurs, mais pas les motos. In­

compréhensible. ..

Tiriana Segato aka. Tüi André, René &: Fabiano

In general The staff of TIPS, BEAMS.

Le Kaf-kaf Sans quoi je me serai endormi...

Friedrich N. & Arthur S.

Benedictus XVI Hé hé. Hem...

Les étudiants de la SBS-EM

le Fonds Van Buuren It is obvions that my PhD could not hâve been

finished without the help of the Fonds Van Buuren. I would like to

express ail my gratitude to this Fonds, and to Monsieur le Baron

Jaumotte.

(8)

Contents

Abstract... iii

Acknowledgements... iv

Table of contents... vi

Nomenclature... xvi

List of tables... xxiii

List of figures...xxvii

Introduction xxxvii Background of this work... xxxvii

General purpose ... xxxvii

Outline ...xxxviii

Activities related to this work... xxxix

Chilean case study... xl Introduction... xl Flowsheet... xli Mixer-settler ... xlvii Columns...xlviii I Solvent extraction 1 1 Principles 3 1.1 Chemical approach... 3

1.2 Extraction reagents... 4

1.2.1 Characteristics... 4

1.2.2 Extractant classes [1]... 5

1.2.3 Mechanisms and kinetics... 9

Mechanisms... 9

Note about kinetics... 10

LIX-860I@... 11

Versatic-10@acid... 13

1.3 Thermodynamics of extraction... 14

1.3.1 Literature... 14

1.3.2 Selectivity... 14

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CONTENTS viii

1.3.3 Détermination of the appropriate value of volumic phase

ratio... 16

1.4 Choice of extraction reagents... 16

1.5 Diluents... 17

Usefulness... 17

Usual diluents... 18

Choice of the diluent... 19

2 Experimental déterminations 21 2.1 Equilibrium constant of an extraction System... 21

2.1.1 Experimental implémentation... 22

2.1.2 Results and discussion... 23

2.1.3 Apparent value of equilibrium constant and extraction yield... 23

2.2 Respective solubilities of organic and aqueous phase... 26

2.2.1 Experimental implémentation... 26

2.2.2 Results and discussion... 27

2.3 Conclusions... 27

II Emulsions 29 3 Properties of émulsions 31 3.1 Chemical and interfacial properties... 31

3.1.1 Composition of the émulsion... 31

The nature of the émulsion... 32

3.1.2 The HLB concept ... 32

3.1.3 The Bancroft rule ... 33

3.1.4 Interfacial tensions... 33

3.1.5 Molecular interactions... 34

The intermolecular forces ... 34

Aqueous phase... 35

Organic phase... 35

Discussion of the different ” water and oil” Sys­ tems ... 35

3.1.6 Preferred curvature... 39

Preferred curvature [2, 3]... 39

3.1.7 Nature of the émulsion - an attempt of synthesis ... 40

3.1.8 Experimental methods for determining superficial / inter facial tensions values... 41

Capillary rising method - Jurin’s law... 41

Horizontal Capillary method ... 41

Falling drop / Stalagmometric method... 42

Pendant drop method: Drop Shape Analysis . . 42

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CONTENTS

IX

Sessile drop method ... 43

du Noüy’s ring method... 44

Wilhelmy’s plate method ... 44

Superficial waves measurement method... 44

Bubble pressure method... 46

Multiphasic equilibrium method... 46

How to détermine interfacial tension when su­ perficial tensions are known... 46

3.2 Electrical properties... 48

3.2.1 Conductivity... 48

Conductivity and nature of the émulsion .... 50

3.2.2 Electrical double layer... 51

3.2.3 Zêta potential of the droplets... 53

3.2.4 Electrokinetic effects... 54

Electrophoresis... 56

Electroosmosis ... 56

Sédimentation potential... 56

Streaming potential ... 58

Emulsions and Electrokinetic effects... 58

3.3 Optical properties ... 59

3.3.1 Scattering and diffraction of a laser beam... 61

Scattering from a single particle... 61

The Mie theory... 63

Rayleigh scattering... 64

The Praunhofer diffraction - forward scattering 65 The geometry optics... 66

Scattering from a population of particles .... 66

Comparison of the different scattering approx­ imations ... 67

The inverse scattering problem... 67

3.3.2 Turbidity... 68

Définition and theoretical background... 68

Drawbacks of the technique... 69

3.3.3 Color ... 70

Relevance... 70

3.4 Experimental déterminations... 73

3.4.1 Interfacial tensions measurements... 73

Experimental... 73

Results and discussion... 75

Conclusions... 80

3.4.2 Conductivity measurements... 80

Experimental... 80

Results ... 80

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CONTENTS

X

4 Emulsification 83

4.1 Introduction... 83

4.2 Thermodynamics of émulsification... 83

4.2.1 Interfacial free energy... 83

4.2.2 Laplace pressure... 84

4.2.3 Viscous dissipation... 86

4.3 Kinetics of émulsification ... 86

4.3.1 Description of mechanisms ... 86

The formation of droplets... 86

Formation of a film... 86

Disruption of a liquid cylinder... 87

Disruption of a plane interface ... 87

The disruption of droplets... 88

Laminar flow... 88

Turbulent flow... 88

4.3.2 Characteristic times... 89

4.4 Techniques of émulsification... 89

4.4.1 Introduction ... 89

4.4.2 Mechanical stirrers... 90

Disperser... 90

Principle... 90

Implémentation... 90

Range of droplet sizes... 91

Homogeneizer... 91

Principle... 91

Implémentation... 91

Range of droplet sizes... 93

4.4.3 Static mixers... 93

Principle... 93

Implémentation... 93

Range of droplet sizes... 93

4.4.4 Phase inversion methods... 94

Principle... 94

Transitional phase inversion... 94

Range of droplet sizes... 94

Catastrophic phase inversion... 94

Implémentation... 95

4.4.5 Membrane émulsification ... 95

Principle... 95

Implémentation... 95

Range of droplet sizes... 95

4.4.6 High pressure homogeneizers... 95

Principle... 95

Implémentation... 95

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CONTENTS xi

Range of droplet sizes... 96

4.4.7 Ultrasound... 96

Principle ... 96

Cavitation... 96

Définition... 96

Mechanism... 97

Relation between cavitation and émulsification 98 Types of cavitation... 98

Cavitation threshold... 99

Relevant parameters of cavitation... 100

Energetic criterion... 101

Implémentation of cavitation... 103

Mechanical ... 103

Electro-mechanical... 104

Time-relative parameters ... 106

Energetic-relative parameters... 107

4.5 The interest of pulsed ultrasound... 108

4.6 Emulsion quality... 112

4.6.1 Introduction ... 112

4.6.2 Droplets size distribution... 112

Review of different parameters characterizing the size distribution... 113

The choice of a parameter to monitor ... 115

4.6.3 Experimental methods for determining droplet size distribution... 119

Optical methods... 119

Photography and shadowscopy... 120

Light scattering...120

Light extinction...121

Phase Doppler Particle Analysis ...121

Holography... 121

Dynamic methods... 122

Settling / Sédimentation... 122

Electric mobility analysis ...123

4.6.4 Choice of the method ...124

4.6.5 Physical stability... 124

5 Emulsification experiments 127 5.1 Experimental...127

5.1.1 Measurements of irradiated power by calorimetry . . . 127

5.1.2 Studied System... 128

5.1.3 Experimental implémentation... 129

Continuons mode... 129

Pulsed mode ...129

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CONTENTS xii

5.2 Results and discussion... 132

5.2.1 Efïect of time-relative parameters...132

Results for LIX-860I... 132

Results for Versatic-10 acid...133

Results for kerosene ... 135

5.2.2 Effect of injected power... 136

5.2.3 Effect of additional mechanical stirring...141

5.3 Conclusions...141

6 Destabilization of émulsions 145 6.1 Processes of destabilization...145

6.2 Emulsion stabilization modes...149

Conclusion ...154

6.3 Effect of ionic strength... 154

6.3.1 Introduction ... 154

6.3.2 Evolution of ionic strength during extraction... 155

6.3.3 Sait sélection... 156

6.3.4 Availability of MgSO^...158

6.3.5 Ionic strength and activity coefficient of MgSO^ . . . 158

6.3.6 Experimental... 160

Studied System...160

Measurement procedure... 160

Results... 161

Discussion... 162

Conclusions... 163

6.3.7 Conclusions...163

III Combinée! efFects of extraction and émulsification 165 7 Kinetics of extraction 167 7.1 Description of the problematics...168

7.1.1 Extraction and diffusion with stirring...168

System description...168

Mass balance of the System... 169

Behavior of the System at t = 0...171

Behavior of the System at time t...171

Analytical solution...172

7.1.2 Limit models...173

Fast reaction... 173

Fast diffusion... 176

Limit model conclusions... 179

7.2 Classical quantification methods ...180

7.2.1 Sampling method... 180

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CONTENTS xiii

Mechanical stirring... 181

Ultrasound stirring... 181

7.2.2 Results ...181

Mechanical stirring... 181

Ultrasound stirring... 182

7.2.3 Conclusions... 183

7.3 Electrochemical cell measurements...183

7.3.1 Introduction ... 183

Choice of électrodes ... 185

7.3.2 Devices...185

Classical cell with AgCl/Ag reference electrode 185 Measurements by concentration cell...187

Liquid junction...188

7.3.3 Experimental implémentation... 190

7.3.4 Results ...194

Results from phase 1... 194

Results from phase 2... 197

7.4 Conclusions... 200

IV Comparisons between classical extraction and ultrasounds- assisted extraction 203 8 Classical flowsheet using LIX-860I(S) 205 8.1 Définition of the problematics and the procedure... 205

8.1.1 Foreword... 205

8.1.2 Assumptions... 205

8.1.3 Model... 207

Initial conditions... 207

Unknown parameters... 208

Resolution...209

8.2 Model robustness... 210

8.3 Kinetics...211

Extraction kinetics... 211

Settling kinetics... 213

8.4 Adaptation to a small plant...213

8.5 Conclusions... 214

9 Comparison of proposed flowsheet using LIX-860I or Versatic- 10@acid 215 9.1 Flowsheet détermination...215

9.2 Equilibrium model results...215

9.2.1 Initial conditions...215

9.2.2 Results ... 216

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CONTENTS xiv

9.3 Kinetics...216

Extraction kinetics... 216

Settling kinetics... 219

9.4 Conclusions...219

V Conclusions 221 Conclusions... 223

Possible applications...227

Appendices 228 A Table of extraction reagents 229 B Extraction equilibrium constant détermination 233 C Measured values of the densities 235 D Signal analysis of the ultrasounds generator 237 Aim... 237

Prequency of the fundamental wave... 237

Link between the mean power injected and the irregularities of square wave .... 237

Link between duty cycle and ultrasounds horn résonance... 241

Répétition rate in pulsed mode...245

E Description of experimental implémentation 247 E.l Analytical devices ...247

E.2 Equipment ... 251

E.3 Emulsification device...251

E.4 Procedure... 252

F Measurements of irradiated power by calorimetry 255 G Calculation of the average value and errors of measurements259 H Results of émulsification experiments 261 Results concerning Versatic-10 acid...261

Results concerning kerosene... 261

Results concerning the power effect...266

I Calculation of ionic strength and activity coefficients 273

J Results of émulsification and extraction kinetics experiments279

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CONTENTS

XV

K Electrochemistry compléments 283

K.l Polarizability of an electrode ...283 K.2 Liquid junction potential... 285 L Calculation procedure for the extraction model 287

M List of reagents used in this work 291

N Note about the choice of experimental techniques of analy­

sis 293

Bibliography 295

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NOMENCLATURE

XVI

Nomenclature Roman letters

a capillary constant ttfc, functions

üx activity of x

a' agglomeration/coalescence parameter A,aq (subscript) refers to the aqueous phase A alkyl group of a hydroxyoxime

A' constant in Szyszkowski expression A

h

Hamaker constant

b curvature radius

B' constant in Szyszkowski expression c speed of light in vacuum

Ci concentration of i-th species Cs speed of sound

Ce correction factor Ci initial concentration Csca scattering cross section Cçt constant

d! smaller diameter of the horn de, dg shape parameters

da diameter of the stirrer d.c. duty cycle

D partition coefficient

D' bigger diameter of the horn Dae aerodynamic diameter

Di extraction factor of i-th species D* diffusion coefficient

D{r) distribution function Dy percentile

D[x,y] mean diameter of x-th and y-th order

<^[3,2] Sauter diameter e charge of the électron

^buik (hypothetical) width of bulk phase

m

mol.L ^ V m m.s~^

mol.L~^

m.s~^

mol.L ^ m

2

m m m

m m

m m m.

C

m

(18)

NOMENCLATURE xvii

Eb

approach to equilibrium -

Ecu

extraction yield wt.% or mol.%

Eequ

equilibrium extraction yield wt.% or mol.%

E

g

Gibbs elasticity J.m~^

E

l

liquid junction potential V

Ereal

real extraction yield wt.% or mol.%

standard potential V

AE°

standard potential différence V

1

e

electric field V.m“^

\Eo\

maximum amplitude of the electric field V.m“^

perpendicular component of the electric vector V.m“^

E\\ parallel component of the electric vector V.m“^

f correction factor

-

/j(u) normalized distribution by number

-

F

force N

F

f

Faraday constant C.mol~^

En

Fresnel number -

9

gravity m.s

_2

g' gain -

9a

asymmetry factor -

velocity gradient s~^

^

G

f

ormation

Gibbs free energy of the formation J.mol~^

of an émulsion

<1

Gibbs free energy of interaction J.mol~^

of the droplets

h height or width m

H

dimensional factor m

AH

enthalpy variation

i summation index -

w concentration of i-th species m,ol.L~^

/ ionic strength m.ol.L~^

lo

initial ionic strength mol.L~^

^ac

acoustic intensity W.m“^

h initial irradiance W.m-2

h scattered irradiance W.m“^

h,T total scattered irradiance W.m“^

h irradiance of transmitted light W.m~^

diffusive flux mol.s~^ .m~^

(19)

NOMENCLATURE xviii k émulsion conductivity

ks Boltzmann constant kc coalescence rate

^œnt conductivity of continuous phase kdisp conductivity of dispersed phase kgx extraction kinetics constant kf agglomération kinetics constant kn wave number

kp dimensionless constant ko wave vector of incident light kg wave vector of scattered light Kd partition equilibrium constant Kex extraction equilibrium constant

i-th proton dissociation equilibrium constant Kg solubility equilibrium constant

K scattering vector L distance

m mass

rrig slope on the log-lin graph of

copper sulfate concentration as a function of potential différence

m„ relative complex refractive index

m' number of distinct droplets in an aggregate M number of items in a sample

n number of items in a sample ria number of aggregates

ne number of électrons implied in a redox n,f number of not agglomerated droplets n-o initial number of droplets

N number of items in a sample

Na

Avogadro number Np power number

Nqp

pumping number rotational speed

O^org (subscript) refers to the organic phase

5 c-l 5 S

dépends on kinetics law

m kg

mol ^

s

-1

(20)

NOMENCLATURE

XIX

P

pressure Pa

p{b) pressure at the interface Pa

PL

Laplace pressure Pa

p{oo) isotropie pressure in the bulk phase Pa

P power W

pp peak power of ultrasound W

Qdisp dispersion fiowrate

Qew

aqueous electrowinning solution fiowrate Q

l

aqueous leaching solution fiowrate

Qp fiowrate

Qr reaction quotient -

Qs scattering efficiency -

Qsx organic phase fiowrate

T ex

extraction rate mol.L~^.s~

r, Ti radius or distance m

ro radius of an emitting surface m

R gas constant J.m.ol-'^.K-

R

q

radius of cavitation nucléus m

Rc threshold radius of cavitation nucléus m

R',R” curvature radius m

Re Reynolds number -

s sait solubility mol.L~^

Sx

experimental standard déviation unit of Xi

estimator of the standard déviation unit of Xi

S surface area m.^ 9

Sint interfacial surface area m?

Ssettler surface of the settler

~s Poynting vector W.m~^

amplitude scattering matrix déterminant -

^ S configuration configurationeil entropy

variation of interfacial surface area m?

t

time s

^oni ^off time on and off of the ultrasound generator s

itotal total time of irradiation s

tx

transport number of species x -

T absolute température K

(21)

NOMENCLATURE

XX

U

U

Usettling

~V Vb

v{Dae)

V V

a

Vint

Vmixer

Vo AV w W

q

We, Wec W

Ws W{r) Wi, W2 Xi Xm

X

y

Z Zc Zi

Z

Zc Z_^

U

electrochemical mobility of an ion mean velocity of a flow

surfacic settling flowrate (velocity) velocity of a charged particle / droplet bulk solution velocity

terminal velocity of a particle with an aerodynamic diameter Dae

volumic fraction of water in the kerosene phase volumic fraction of kerosene in the kerosene phase volume

volume of aqueous phase interfacial volume volume of the mixer volume of organic phase

sédimentation or streaming potential stoechiometric coefficient

characteristic dimension of laser beam spot size Weber number

power

scattered power weighting function Work

resuit of i-th measurement arithmetic mean of Xj horizontal coordinate vertical coordinate

stoechiometric coefficient or valence cavitation limit ordinate

charge of i-th species

acoustic impédance of the medium electric mobility of a particle impédance of voltmeter normal vector

m.s~^

m.s~^

,s~^ .m~'^

m.s~^

m.s~^

m.s~^

m m m m m

3 3 3 3 3

V m W W J

unit of Xi m

m m

kg.m~^ ,s~^

m?'.s.V~^

Ü

(22)

NOMENCLATURE

XXI

Greek letters

a a\

/j

«s

«d a' PS

P'

X

Ô

n

e CH

£, £*

Vv, Vd

<p{x,t)

7

7x

70 7oo

r

poo K A A Mo

^répétitions ^rep

l'i 7T

7

t

(/

i

) T^x v>

^'o

value of t-student probability distribution séparation factor of i-th and j-th species dimensionless size parameter

dampening coefficient of the medium parameter

absorption coefficient

overall proton dissociation equilibrium constant parameter

extinction coefficient

width of the diffusive boundaxy layer permittivity

relative permittivity wetting / contact angle

mass proportion of i-th component in the phase containing water mass proportion of i-th component in the phase containing kerosene dynamic viscosity

contact angle azimuthal angle overall diffusive flux interfacial tension

activity coefficient of species x

interfacial tension without extraction reagent interfacial tension if aqueous phase has an infinité extent

surface excess

surface excess when interface is saturated Debye-Hückel reciprocal length

wavelength turbidity

vacuum permeability répétition rate

stoechiometric coefficicient mathematical constant pi disjoining pressure

disjoining pressure contribution due to x scattering angle

potential in the electrical double layer Nernst potential

Stern potential

m~^

m.ol.L~^

m~^

mol.L~^

m~^

m F/m rad

Pa.s rad rad mol.m~^

J.m~^

J.m~^

J.m~^

mol.L~^

mol.L~^

m~^

m m~^

H.m-^

Pa

Pa

rad

V

V

V

(23)

NOMENCLATURE xxii

Pa Pa Pa Pk

Pk

Pliquid Pvapor Ap

a

Tads

’^col

’^def '^mixer

9

^p, c

ÜJ U>M

relative density of the aqueous phase relative density of the aqueous phase relative density of the aqueous phase relative density of the kerosene phase relative density of deionized water relative density of kerosene

relative density of liquid phase relative density of gaseous phase différence of relative densities superficial tension

characteristic adsorption time characteristic collision time characteristic deformation time résidence time in the mixer characteristic pressure time

characteristic interfacial tension time characteristic viscosity time

half life of émulsion towards agglomération volume phase ratio

(pseudo) extent of reaction angle

zêta potential angular frequency Minneart frequency

kg.m”^

kg.m“^

kg.m~^

kg.m”^

kg.m~^

kg.m~^

kg.m“^

kg.m“^

kg.m~®

J.m~^

s s s s s s s s

mol.L ^ rad V rad.s~^

rad.s~^

(24)

List of Tables

1 Ores found in different mineralizations of copper deposits.

Notice that dénominations of oxide and sulfide are only used for convenience, because silicates and carbonates are usually classified in oxide category. ... xliii 1.1 Required characteristics of extraction reagents... 5 1.2 Nature, lUPAC name and trade name of some of the second

génération oximes... 7 1.3 lUPAC name, trade name and solubilities of Versatic@acids. 10 1.4 Table of parameters related to fire bazards, human toxicity

and ecotoxicity for LIX-860I and Versatic-10 acid... 17 1.5 Table of commercially available diluents... 19 1.6 Composition of ORFOM SX-12 kerosene [4]... 20 2.1 Initial concentrations of species implied in extraction equilib-

rium... 22 3.1 Désignation and continuons phase... 32 3.2 HLB values and desired applications... 33 3.3 Table of energies for different intermolecular/interionic forces,

reproduced from [5]... 34 3.4 Table showing the four conductivity expressions used, and

their limit when the dispersed phase conductivity tends to- wards zéro... 50 3.5 Classification of electrokinetics effects according to the cause/effect

relation. Reproduced from [6]... 55 3.6 Value of and type of diffraction... 65 3.7 Results of superficial tensions measurements on copper sulfate

solutions... 75 3.8 Results of superficial tensions measurements on Kerosene -

LIX Systems... 75 3.9 Results of superficial tensions measurements on Kerosene -

Versatic-10 acid Systems... 76

(25)

LIST OF TABLES xxiv 3.10 Results of superficial tensions measurements on aqueous phase

put in contaict with Kerosene containing Versatic-10 aoid or LIX-8601... 77 3.11 Results of interfaoial tensions measurements on buffered aque­

ous solutions contacted with kerosene containing Versatic-10 acid or LIX-8601... 79 5.1 Value of the mean power injected in the medium as a func-

tion of the cursor position. Error on mean power injected is estimated at 2W according to the results of calorymetry experiments presented in Appendix F... 128 5.2 Duty cycles and corresponding irradiation times...130 5.3 Experimental parameters and their values used in experi­

ments - LIX-8601... 130 5.4 Combination of values of d.c. and Urep used in experiments

for LIX-8601. A ’X’ shows a tested combination of values. . . 130 5.5 Experimental parameters and their values used in experi­

ments - Versatic-10 acid...131 5.6 Combination of values of d.c. and i^rep used in experiments for

Versatic-10 acid. A ’X’ shows a tested combination of values. 131 5.7 d[3;2] obtained for experiments in the case of organic phase

containing kerosene and LIX-8601, stirring provided by the use of ultrasound only, and répétition rate equal to 1.67s“^. . 132 5.8 d[3;2] obtained for experiments in the case of organic phase

containing kerosene and LIX-8601, stirring provided by the use of ultrasound and mechanical means, and répétition rate equal to 1.67s“^...132 5.9 d[3;2] obtained for experiments in the case of organic phase

containing kerosene and Versatic-10 acid (15 %vol), stirring provided by the use of ultrasounds only, and répétition rate equal to 0.17s“^...134 5.10 d[3;2] obtained for experiments in the case of organic phase

containing kerosene only, stirring provided by the use of ul­

trasounds only, and répétition rate equal to 0.17s“^...136 5.11 Comparison of d[3;2] plateau values obtained for experiments

with organic phase containing either LIX-8601 or Versatic-10 acid, or kerosene only, stirring provided by the use of ultra­

sounds only...137 5.12 Values of mean power averaged on time related to the values

of duty cycle &: power peak... 137 5.13 d[3;2] obtained for experiments in the case of organic phase

containing Versatic-10 acid, stirring provided by the use of

ultrasound only...139

5.14 d[3;2] values obtained in plateau for experiments...139

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LIST OF TABLES

XXV

6.1 Initial concentrations of aqueous species in our extraction Sys­

tem... 156 6.2 Table of common sulfate salts - Solubility is given in water

at 25°C... 157 6.3 Table of soluble magnésium minerai usually encountered [7, 8]. 159 6.4 Table of values of MgS04 concentrations used in the experi-

ments, and the related values of ionic strength... 161 6.5 Table of values of d[3; 2] (and error) obtained for different

values of ionic strength... 161 7.1 Réduction potential of the AgCl/Ag electrode for varions

températures, for saturated KCl and 3.5 m.ol.L~^ KCl. Re- produced from [9]... 187 7.2 Values of concentrations of copper sulfate solutions we used

in our experiments... 190 7.3 Values of parameters used in émulsification experiments with

LIX-8601... 191 7.4 Values of parameters used in émulsification experiments with

Versatic-10 acid... 192 7.5 Potential différence measured between the électrodes of se-

tups 1, 2 and 3 as a function of copper ion concentration in measurement cell solution - comparison with values of Nernst’s related expression of potential - calculation led with the activities... 195 7.6 Potential différence measured between the électrodes of se-

tups 4 and 5 as a function of copper ion concentration in mea­

surement cell solution - comparison with values of Nernst’s related expression of potential - calculation led with activities. 197 7.7 Comparison of initial extraction rates obtained for LIX-8601

and Versatic-10 acid with mechanical or ultrasound stirring. . 199 8.1 Initial conditions of our model... 209 8.2 Comparison of values characteristic of Quebrada Blanca op­

eration and calculated values using model... 210 B.l Results of extraction equilibrium constant détermination. . . 233 D. l Value of the correction for the mean power irradiated in the

System as a conséquence of the rise and drop times of tension impulsion, as a function of impulsion times...243 E. l Copper émission spectral lines used in ICP-OES measure-

ments - in aqueous phase... 248 E.2 Copper émission spectral lines used in ICP-OES measure-

ments - in organic phase... 248

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LIST OF TABLES xxvi E.3 Important parameters of the density meter...249 E. 4 Linear corrélation between power and cursor position... 252 F. l Value of the mean power injected in the medium as a function

of the cursor position... 257 G. l Values of the t-distribution parameter as a function of sample

size n and confidence interval... 260 H. l d[3;2] obtained for experiments in the case of organic phase

containing kerosene and Versatic-10 acid, stirring provided by the use of ultrasounds only, and répétition rate equal to 0.17s-^... 261 H.2 d[3;2] obtained for experiments in the case of organic phase

containing kerosene and Versatic-10 acid, stirring provided by the use of ultrasounds only, and répétition rate equal to 1.67S-1... 262 H.3 d[3;2] obtained for experiments in the case of organic phase

containing kerosene and Versatic-10 acid, stirring provided by the use of ultrasounds only, and répétition rate equal to 16.7s-^... 262 H.4 d[3;2] obtained for experiments in the case of organic phase

containing kerosene and Versatic-10 acid, stirring provided by the use of ultrasounds and mechanical means, and répétition rate equal to 0.17s“^... 262 H.5 d[3;2] obtained for experiments in the case of organic phase

containing kerosene and Versatic-10 acid, stirring provided by the use of ultrasounds and mechanical means, and répétition rate equal to 1.67s“^... 263 H.6 d[3;2] obtained for experiments in the case of organic phase

containing kerosene and Versatic-10 acid, stirring provided by the use of ultrasounds and mechanical means, and répétition rate equal to 16.7s“^... 263 H.7 d[3;2] obtained for experiments in the case of organic phase

containing kerosene only, stirring provided by the use of ul­

trasounds only, and répétition rate equal to 0.17s“^...263 H.8 d[3;2] obtained for experiments in the case of organic phase

containing kerosene only, stirring provided by the use of ul­

trasounds only, and répétition rate equal to 1.67s~^...264 H.9 d[3;2] obtained for experiments in the case of organic phase

containing kerosene only, stirring provided by the use of ul­

trasounds only, and répétition rate equal to 16.7s~^... 264

(28)

LIST OF TABLES

XXVll

H.10 d[3;2] obtained for experiments in the case of organic phase

containing kerosene only, stirring provided by the use of ul- trasounds and mechanical means, and répétition rate equal to0.17s-^... 264 H.11 d[3;2] obtained for experiments in the case of organic phase

containing kerosene only, stirring provided by the use of ul- trasounds and mechanical means, and répétition rate equal to 1.67s“^... 265 H. 12 d[3;2] obtained for experiments in the case of organic phase

containing kerosene only, stirring provided by the use of ul- trasounds and mechanical means, and répétition rate equal to 16.7S-1... 265 H.13 d[3;2] obtained for experiments in the case of organic phase

containing Versatic-10 acid, stirring provided by the use of ultrasounds only... 266 H.14 d[3;2] obtained for experiments in the case of organic phase

containing Versatic-10 acid, stirring provided by the use of ultrasounds and mechanical means... 267 H. 15 d[3;2] obtained for experiments in the case of organic phase

containing kerosene only, stirring provided by the use of ul­

trasounds only... 268 H. 16 d[3;2] obtained for experiments in the case of organic phase

containing kerosene only, stirring provided by the use of ul­

trasounds and mechanical means... 269 I. 1 Ionie strength for different values of MgSOi anal3dical con­

centration -

lestimated

îs the ionic strength calculated without the effect of activities, and

Icorrected

takes into account the ef- fect of activities... 276 J. l Extraction reagents used, stirring power used, measured cop-

per ion concentrations before and after sampling, and calcu­

lated initial extraction rates... 280

(29)

LIST OF TABLES xxviii

(30)

List of Figures

1 Flowsheet of Quebrada Blanca hydrometallurgical plant. . . . xlii 2 Picture of a sample of dispersion of aqueous and organic

phases which was withdrawn from a mixer/settler device from Quebrada Blanca plant...xliv 3 Picture of a row of copper cathodes being recovered from

electrolytic cell, in the copper electrowinning hall of Quebrada Blanca plant... xlvi 4 Sketch of a mixer-settler device. Reproduced from [10]...xlvii 5 Sketch of packed and puise columns. Reproduced from [Ij. . . xlix 6 Sketch of rotating disks column. Reproduced from [1]...xlix 1.1 Extraction curve of copper ions by Versatic-10@acid and

other extractants [11]... 4 1.2 Chemical structure of the active compound of second génér­

ation hydroxyoxime reagents... 6 1.3 Chemical structure of the active compound of LIX-63@. ... 7 1.4 Chemical structure of the active compound of LIX-6x(§)series. 8 1.5 OverView of hydroxyoximes classification... 8 1.6 Chemical structure of the active compound of Versatic-10(S)acid.

The sum of the numbers of carbon atoms in R and R' equals eight... 9 1.7 Steps occuring during extraction in dispersion... 10 1.8 Extraction curves of metallic ions by salycilaldoxime. Repro­

duced from [12] 15

2.1 Extraction isotherm of copper ion by LIX-860I - Initial pH 2.0 ; copper ion initial concentration 0.087mol.L~^ ; Extrac­

tion reagent initial concentration 0A5mol.L~^ - Ultrasound

power is set at 14.9W - Mechanical stirrer power is set at

12.2W... 24

(31)

LIST OF FIGURES

XXX

2.2 Evolution of the extraction yield Ecu ^ a fonction of 6. Ini­

tial pH 2.0 ; copper ion initial concentration 0.087mol.L~^ ; Extraction reagent initial concentration 0A5mol.L~^ - Ultra- sound power is set at 14.9W - Mechanical stirrer power is set at 12.2W and T = 293R:... 25 3.1 Formula of LIX-860I@ ... 35 3.2 Formula of Versatic-10@ acid... 35 3.3 Water/dodecane System... 36 3.4 Water/dodecane containing LIX-860I System... 37 3.5 Dodecane/air containing LIX-860I System... 38 3.6 Air/water containing aqueous emulsifier System... 39 3.7 Stronger interactions on the water side... 39 3.8 Equal interactions on both sides ... 40 3.9 Stronger interactions on the oil side ... 40 3.10 Principle of the horizontal capillary method, taken from [13] . 42 3.11 Profile of a pendant droplet, taken from [13]... 43 3.12 Profile of a sessile droplet on a plate, taken from [13]... 44 3.13 du Noüy’s ring technique, taken from [13]... 45 3.14 Wilhelmy’s plate technique, taken from [13]... 45 3.15 Diagram of t-wo liquids phases in contact with a solid phase . 47 3.16 Sessile drop measurements for kerosene... 47 3.17 Sessile drop measurements for water... 48 3.18 Calculated émulsion conductivity (in mS/cm) as a fonction

of volumic fraction 9 when k^isp —>■ 0, with different models.

A value of conductivity of water has been measured and used as kcont = (6 ± 1) X 10“^ mS/cm for establishing this curve. . 51 3.19 Sketch of an electrical double layer with counter-ion adsorption. 52 3.20 Sketch of potential behavior in the electrical double layer with

counter-ion adsorption... 53 3.21 Sketch of potential behavior in the electrical double layer with

counter-ion adsorption and charge reversai... 54 3.22 Sketch of an electronegative particle and its plane of shear in

an electrolyte solution. Water molécules are not depicted. . . 55 3.23 Principle of electrophoresis, with droplets negatively charged. 57 3.24 Principle of sédimentation potential, with droplets negatively

charged in the field of gravity... 57 3.25 Scattering geometry, taken from [14]... 63 3.26 Two-dimensional scattering intensity pattern for Mie scatter­

ing, taken from [15]... 64 3.27 Sketch of an online turbidimetry device, taken from [16]. . . . 70 3.28 Figure showing the évolution of the superficial tension of cop­

per sulphate solution as a fonction of copper sulphate concen­

tration... 76

(32)

LIST OF FIGURES

XXXI

3.29 Figure showing the évolution of the superficial tension of or- ganic phase as a function of volumic percentage of extraction reagent... 77 3.30 Figure showring the évolution of the superficial tension of wa-

ter contactée! with Kerosene containing Versatic-10 acid / LIX-8601... 78 3.31 Figure showing the évolution of the interfacial tension of buffered

aqueous solutions contacted with kerosene containing Versatic- 10 acid / LIX-8601... 79 3.32 Comparison between calculated and measured émulsion con-

ductivities (in mS/cm) as a function of volumic fraction 9 when kdisp 0, with different models. A value of con- ductivity of water has been measured and used as kemt = (6 ± 1) X 10 ^ mS/cm to establish the theoretical curves. . . 82 4.1 General principle of émulsification process... 84 4.2 Small section of a curved surface displaced from equilibrium. 85 4.3 W6c as a. function of ^ for simple shearing case - Continuons

curve corresponds to a static mixer, and dots to a colloidal mill [17]... 88 4.4 Principle of a rotor-stator device, reproduced from [18]. ... 92 4.5 Principle of a colloidal mill, reproduced from [18]... 92 4.6 Principle of an homogeneizer batch tank, reproduced from [19]. 93 4.7 Principle of a transitional phase inversion method, taken from

[18]... 94 4.8 Depiction of boiling and cavitation on a schematic phase di-

agram (of water)... 97 4.9 Hydrostatic pressure as a function of the bubble nucléus ra­

dius - Représentation for two initial nucléus radii - Repro­

duced from [20]... 99 4.10 Depiction of the cavitation threshold when applying acoustic

field to System... 101 4.11 Zone of the System where cavitation threshold is reached. . . 103 4.12 Whistle device principle...104 4.13 Geometry and construction of our ultrasound horn... 105 4.14 Picture of widespread ultrasound horns, reproduced from [21]. 106 4.15 Power injected in the medium irradiated by pulsed ultrasound

as a function of time...107

4.16 Schematic comparison of Tj-ad and r^e/, and related events. . . 110

4.17 Schematic comparison of Tads and T

co

I, and related events. . . 111

4.18 Situation is favorable in pulsed mode... 111

4.19 Situation is unfavorable in continuons mode... 112

4.20 Example of simple volumic percentage distribution... 114

4.21 Number distribution barchart for two droplet populations. . . 116

(33)

LIST OF FIGURES

XXXll

4.22 Comparison of the interfacial surface areas of the two popu­

lations ... 117 4.23 Comparison of the volumic distribution of the two populations 118 4.24 Value of the different parameters for the two droplets popu­

lations...118 4.25 Diagram of Light Scattering techniques implémentation. . . . 120 4.26 Principle of the recording of an hologram... 122 4.27 Settling chamber with aérosol and air intake - depiction of

the particle sorting by settling... 123 5.1 d[3;2] as a function of ton- Organic phase is kerosene con-

taining LIX-860I (15%uo/), and stirring is provided either by ultrasound only, or ultrasound and additional mechanical stirring... 133 5.2 d[3;2] as a function of ton- Organic phase is kerosene contain-

ing Versatic-10 acid (15 %vol), and stirring is provided by either ultrasounds or ultrasound and additional mechanical stirrer. Legend shows values (in %) of varying duty cycle - horizontal lines show d[3;2] for continuons ultrasound for each case... 135 5.3 d[3;2] as a function of ton- Organic phase is kerosene, and

stirring is provided by ultrasound only. Legend depicts the values of mean power related to duty cycle values... 138 5.4 d[3;2] as a function of duty cycle. Organic phase is kerosene,

and stirring is provided by ultrasound only. Only the data corresponding to the plateau values of Figure 5.3 hâve been considered... 140 5.5 d[3;2] value in plateau as a function of injected power. Or­

ganic phase is kerosene containing Versatic-10 acid or kerosene only, and stirring is provided by ultrasound only or ultrasound and mechanical stirrer... 141 5.6 Plateau value of d[3;2] as a function of injected power and the

stirring mode. Organic phase is kerosene containing Versatic- 10 acid {I0%vol)... 142 5.7 Synoptic overview of the effect of the parameters on the d[3,2]

évolution in our System. Mean Pas représenta the mean

power averaged on time. Pus représenta the injected power,

ton représenta the time of the ultrasound impulsion, Versatic-

10 acid représenta the presence of this extraction reagent,

and Mech. stirring représenta the presence of additional

mechanical stirring... 143

6.1 Film of continuons phase (3 between droplets of phase a. .. . 147

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LIST OF FIGURES xxxiii 6.2 Sketch of potential behavior in electrical double layer with

counter-ion absorption... 151 6.3 Sketch of equilibrium position of a solid particle at the inter­

face between dispersed and continuons phases... 151 6.4 Sketch of different positions of a solid particle in a dispersed

System... 152 6.5 Geometry of a solid particle at the interface between dispersed

and continuons phases...153 6.6 Evolution of ionic strength of MgS04 solution as a function

of C

SO

a

...160 6.7 Evolution of of d[3; 2] as a function of time and ionic strength

- ’TS” means ionic strength in the graph... 162 7.1 Depiction of the System when t = 0...

7.2 Depiction of the System for a time t...

7.3 Depiction of the System in fast reaction case for a time t. . . 7.4 Depiction of the System kinetics: concentration logarithm as

a function of time...

7.5 Depiction of the System in fast diffusion case for a time t. . . 7.6 Description of the évolution of the apparent extraction rate

as a function of the interfacial surface area...

7.7 Evolution of the apparent extraction rate as a func­

tion the stirring power

7.8 Setup of a classical cell with AgCl/Ag reference electrode measurement device...

7.9 Setup of a concentration cell measurement device. Copper wire is usual electrical conductor. Liquid junction was car- ried out by using either KCl or K2SO4 in gelified agar-agar.

Température was 293/tT and pi/ = 4.1. Copper ion concentra­

tions X were made varying between 10“^ and 8x 10“^ m.ol.L~^

during test phase of the electrochemical cell...

7.10 Setup of a AgCl/Ag wire plunged in the measurement cell.

Copper wire is usual electrical conductor. Température was 293A and pH = 4.1. Copper ion concentrations x were made varying between 10“^ and 8x 10"^ mol.L~^ during test phase of the electrochemical cell...

7.11 Setup of a AgCl/Ag reference electrode with double liquid junction. Copper wire is usual electrical conductor. Tempér­

ature was 293A and pH = 4.1. Copper ion concentrations X were made varying between 10~‘^ and 8 x 10“^ mol.L~^

during test phase of the electrochemical cell...

171 172 174 176 177 180

182 186

189

193

194

(35)

LIST OF FIGURES

XXXIV

7.12 Potential différence measured between the électrodes in our

System as a function of copper ion concentration in the mea- surement cell solution - comparison with values of Nernst’s related expression of potential... 196 7.13 Potential différence measured between the électrodes in our

System as a function of copper ion concentration in measure- ment cell solution - comparison with values of Nernst’s related expression of potential... 198 7.14 Evolution of the copper ion concentration as a function of

time for LIX-860I émulsification and extraction kinetics ex- periments. Comparison of mechanical and ultrasound stirring. 199 7.15 Evolution of the copper ion concentration as a function of

time for Versatic-10 acid émulsification and extraction kinet­

ics experiments. Comparison of mechanical and ultrasound stirring... 200 7.16 Evolution of the copper ion concentration as a function of

time for Versatic-10 acid émulsification and extraction kinet­

ics experiments. Effect of extraction reagent volume percentage.201 8.1 Diagram of stagewise extraction at Quebrada Blanca hydromet-

allurgical plant - 0 is the volume phase ratio in the considered extraction or stripping stage... 206 8.2 Diagram of single stage extraction using LIX-8601... 208 8.3 (a) Effect of varying C

rh

on di. (b) Effect of varying Kgx on

6i

...212 9.1 Spreadsheet used to résolve the model in case of Versatic-10

acid. C

r

^

h

2 — 217

9.2 Spreadsheet used to résolve the model in case of Versatic-10 acid with an analytical concentration of 0.8m.ol.L~^... 218 9.3 Sketch of a possible ultrasound extraction reactor based on

existing cascade continuons stirred-tank reactors... 219 A.l OverView of extraction reagents spécifie for copper... 230 A.2 OverView of extraction reagents spécifie for copper - continued.231 A.3 OverView of extraction reagents spécifie for copper - continued.232 C.l Densities measured prior to inter facial tension measurements. 236 D. 1 Graph of alternate tension supplied to to the ultrasounds horn

as a function of time, in continuons mode... 238 D.2 Fourier’s transform of the signal supplied to the horn in con­

tinuons mode... 238 D.3 Fourier’s transform of the signal supplied to the horn in pulsed

mode...239

(36)

LIST OF FIGURES

XXXV

D.4 Square wave supplied by the generator to the ultrasounds horn when the device use pulsed mode. Répétition rate is equal to 1.67Hz and duty cycle is equal to 50 %...239 D.5 Square wave supplied by the generator linked to the ultra­

sounds horn when the device use pulsed mode. Répétition rate is equal to 1.67Hz and duty cycle is equal to 50 %. ... 240 D.6 Square wave supplied by the generator without link to the ul­

trasounds horn when the device use pulsed mode. Répétition rate is equal to 1.67Hz and duty cycle is equal to 50 %. ... 241 D.7 Behavior of the tension supplied to the ultrasounds horn when

triggered... 242 D.8 Behavior of the tension supplied to the ultrasounds horn when

triggered... 242 D.9 Square wave supplied by the generator to the ultrasounds

horn when the device use pulsed mode. Répétition rate is equal to 1.67Hz and duty cycle is equal to 16.7%...243 D. 10 Square wave supplied by the generator to the ultrasounds

horn when the device use pulsed mode. Répétition rate is equal to 1.67Hz and duty cycle is equal to 16.7%. Timescale redimensioned... 244 E.l DSA15 device used for superficial and interfacial tension mea-

surements... 249 E.2 Sketch of setup used for interfacial tension measurement. . . . 250 E.3 Mastersizer - S Long bench from Malvern instruments. The

figure depicts: (1) the optical unit - (2) a sample préparation accessory - (3) the computer... 251 E.4 Geometry and construction of our ultrasound horn...253 E. 5 OverView of the full setup used in our experiments...253 F. l Evolution of the instantaneous power and mean power in-

jected by the ultrasounds generator as a function of time.

Cursor position equals 9... 257 F.2 Evolution of the mean injected power as a function of time

for different positions of the cursor...258 F.3 Mean injected power as a function of time and position of the

cursor - t = 1000 s... 258 H.l d[3;2] as a function of ton- Organic phase is kerosene only,

and stirring is provided by ultrasounds only. Legend shows values (in %) of varying duty cycle... 267 H.2 d[3;2] as a function of ton- Organic phase is kerosene only, and

stirring is provided by ultrasounds and additional mechanical

stirrer. Legend shows values (in %) of varying duty cycle. . . 268

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LIST OF FIGURES xxxvi H.3 d[3;2] as a function of of ton- Organic phase is kerosene, and

stirring is provided by ultrasound only...269 H.4 d[3;2] as a function of of ton- Organic phase is kerosene, and

stirring is provided by ultrasound and additional mechauical stirrer... 270 H.5 d[3;2] as a function of of ton- Organic phase is kerosene con-

taining Versatic-10 acid, and stirring is provided by ultra­

sound only. ...270 H. 6 d[3;2] as a function of of ton- Organic phase is kerosene con-

taining Versatic-10 acid, and stirring is provided by ultra­

sound and additional mechanical stirrer... 271 I. l Evolution of log(7Mÿ2+) as a function of log(/)...275 1.2 Evolution of log(7^Q2-) as a function of log(/)... 275 1.3 Evolution of log(7;\/gso4) as a function of log(/)... 276 1.4 Evolution of ionic strength of MgSOi solution as a function

oiCMgSOi... 277 J.l Results obtained for LIX-860I émulsification and extraction

kinetics experiments... 280 J. 2 Results obtained for Versatic-10 acid émulsification and ex­

traction kinetics experiments... 281 K. l Evolution of the electrode potential as a function the net cur-

rent density for a polarizable electrode... 284 K. 2 Evolution of the electrode potential as a function the net cur-

rent density for a non polarizable electrode...284

L. l Diagram of single stage extraction... 287

(38)

Introduction

Background of this work

rpms work takes part in a project led in collaboration with the chilean universities Universidad de Concepciôn (located in Concepciôn) and Universidad Arturo Prat (located in Iquique), and belgian universities Uni­

versité de Liège and Université Libre de Bruxelles. This project aims at developing and designing new extractive metallurgy processes, which would be suited to local exploitation of small copper ore deposits. In these con­

ditions, the plant has to be as compact as possible in order to be easily transported from a deposit to a subséquent one.

In Chile, mostly large but less concentrated deposits are already ex- ploited by industrial installations. Few small copper ore deposits are mined, and the ore is sent with difficulty to the large industrial installations. These installations exhibit a conventional flowsheet which uses leaching (usually heap leaching), solvent extraction (usually multi-stage) and electrowinning.

The required infrastructure and the amount of métal immobilized may be large, in order to ensure high recovery yield and productivity. Massive in­

stallations require high capital and operating costs, and are meaningful only if the deposit is large enough to be exploited according a suited paying off timespan. This excludes this kind of installations to exploit small deposits which give no guaxantee of such paying off timespan. The exploitation of these small deposits would then require smaller installations and benefit by new technology, in order to limit résidence time of the métal and maintain productivity. These installations should also exhibit modularity, in order to ease their transport and deployment on the field.

The présent PhD concerns the détermination of the relevance of a par- ticular solvent extraction technique, and its possible implémentation in in- dustry.

Some of the objectives of the aforementioned project hâve already been realized thanks to collaborations between Université de Liège, Universidad de Atacama (located in Copiapô) and Universidad Arturo Prat (located in Iquique) on one hand, and collaborations between Universidad de Con­

cepciôn (located in Concepciôn) and Université Libre de Bruxelles, on the

other hand.

Figure

Updating...

Références

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