Extractive Metallurgy 1: Basic Thermodynamics and Kinetics

361 Pages·2011·12.4 MB·English

by  Alain Vignes(auth.)

Extractive Metallurgy 1
Extractive Metallurgy 1
Basic Thermodynamics and Kinetics

Alain Vignes
First published 2011 in Great Britain and the United States by ISTE Ltd and John Wiley & Sons, Inc.
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The rights of Alain Vignes to be identified as the author of this work have been asserted by him in
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____________________________________________________________________________________
Library of Congress Cataloging-in-Publication Data

Vignes, Alain.
Extractive Metallurgy 1/ Alain Vignes.
p. cm.
Includes bibliographical references and index.
ISBN 978-1-84821-160-5
1. Metallurgy--Handbooks, manuals, etc. 2. Extraction (Chemistry)--Handbooks, manuals, etc. I. Title.
TN671.V54 2011
669--dc22
2010031981

British Library Cataloguing-in-Publication Data
A CIP record for this book is available from the British Library
ISBN 978-1-84821-160-5

Printed and bound in Great Britain by CPI Antony Rowe, Chippenham and Eastbourne.
Table of Contents
Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
Chapter 1. Metallurgical Thermochemistry . . . . . . . . . . . . . . . . . . . . 1
1.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2. Quantities characterizing the state of a system and its evolution . . . . 3
1.2.1. The types of operations . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2.2. Stoichiometric description of a chemical system . . . . . . . . . . . 4
1.2.3. Evolution of a system’s state: degree of advancement of a
reaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.2.4. Characteristic quantities of a phase’s composition . . . . . . . . . . 11
1.3. Thermodynamic fundamentals of reactions . . . . . . . . . . . . . . . . . 16
1.3.1. Reaction enthalpy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
1.3.2. Gibbs free energy of a system, affinity of a reaction and
chemical potential of a component . . . . . . . . . . . . . . . . . . . . . . . 18
1.3.3. Expressions of the chemical potential and activities of a
component . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
1.3.4. Affinity of a reaction: law of mass action (thermodynamic
modeling of a process) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
1.3.5. Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
1.4. Phase diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
1.4.1. Binary phase diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
1.4.2. Ternary phase diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . 36
1.5. Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Chapter 2. Oxides, Sulfides, Chlorides and Carbides . . . . . . . . . . . . . . 41
2.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
2.2. Metal-oxygen/metal-sulfur systems activities in the intermediate
phases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
vi Extractive Metallurgy 1
2.2.1. Phase diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
2.2.2. Component activities in the intermediate phases . . . . . . . . . . . 46
2.3. Standard Gibbs free energy: temperature diagrams for oxides –
Ellingham-Richardson diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . 51
2.3.1. Stoichiometric oxides . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
2.3.2. Unstoichiometric compounds . . . . . . . . . . . . . . . . . . . . . . . 54
2.3.3. Thermodynamic data for the reduction of oxides by a
reducing gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
2.4. Thermodynamic data for sulfides and chlorides . . . . . . . . . . . . . . 58
2.4.1. Ellingham-Richardson diagram for sulfides . . . . . . . . . . . . . . 58
2.4.2. Stability diagrams for the (M-O-S) systems . . . . . . . . . . . . . . 60
2.4.3. Ellingham-Richardson diagram for chlorides . . . . . . . . . . . . . 62
2.4.4. Stability diagrams of M-O -Cl systems . . . . . . . . . . . . . . . . 62
2 2
2.5. Metal-carbon phase diagrams and the Ellingham-Richardson
diagram for carbides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
2.6. Carbon and carbon oxide reactions . . . . . . . . . . . . . . . . . . . . . . 67
2.6.1. Oxidation reactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
2.6.2. Boudouard’s reaction . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
2.6.3. The different types of coal . . . . . . . . . . . . . . . . . . . . . . . . 70
2.7. Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Chapter 3. Metal Solutions, Slags and Mattes . . . . . . . . . . . . . . . . . . . 73
3.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
3.2. Metal solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
3.2.1. Phase diagrams and activities of liquid alloys components . . . . . 74
3.2.2. Activities and solubilities of metalloids in metal solutions . . . . . 83
3.2.3. Solubility and precipitation of oxide and sulfide compounds
in metals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
3.3. Mattes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
3.3.1. Structure and physical properties of sulfide melts (mattes) . . . . . 93
3.3.2. Thermodynamic data for the binary Fe-S, Ni-S, Cu-S and
Pb-S systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
3.3.3. Thermodynamic data of ternary mattes . . . . . . . . . . . . . . . . . 97
3.3.4. Thermodynamic data for M-O-S systems . . . . . . . . . . . . . . . . 99
3.4. Slags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
3.4.1. Structure and physical properties . . . . . . . . . . . . . . . . . . . . . 106
3.4.2. Phase diagrams and activities . . . . . . . . . . . . . . . . . . . . . . . 110
3.4.3. Phase diagrams and activities of oxide mixtures forming the
basis of metallurgical slags CaO-SiO -Al O -MgO . . . . . . . . . . . . . 111
2 2 3
3.4.4. Phase diagrams and activities of mixtures of
CaO-SiO -Al O -MgO oxides and reducible (iron, manganese and
2 2 3
chrome) oxides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
3.5. Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
Table of Contents vii
Chapter 4. Aqueous Electrolytic Solutions and Salt Melts . . . . . . . . . . . 131
4.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
4.2. Thermodynamics of aqueous electrolyte solutions . . . . . . . . . . . . . 131
4.2.1. Chemical potentials and activities of the components of
electrolyte aqueous solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
4.2.2. Aqueous solutions of acids and bases . . . . . . . . . . . . . . . . . . 138
4.2.3. Aqueous solutions of metallic salts: complexation and
speciation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
4.2.4. Solubility of oxides and hydroxides . . . . . . . . . . . . . . . . . . . 156
4.2.5. Solubility of salts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
4.2.6. Solubility of gases in an aqueous solution . . . . . . . . . . . . . . . 171
4.3. Thermodynamics of salt melts (fluxes) . . . . . . . . . . . . . . . . . . . 173
4.3.1. Compositions and physical properties of fluxes . . . . . . . . . . . . 174
4.3.2. Thermodynamic properties . . . . . . . . . . . . . . . . . . . . . . . . 174
4.3.3. Solubility of oxides in halides . . . . . . . . . . . . . . . . . . . . . . 177
4.4. Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179
Chapter 5. Reaction Kinetics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
5.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
5.2. Rate of a chemical reaction . . . . . . . . . . . . . . . . . . . . . . . . . . 184
5.2.1. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184
5.2.2. Expressions of the rate of a chemical reaction . . . . . . . . . . . . . 186
5.3. Homogeneous precipitation . . . . . . . . . . . . . . . . . . . . . . . . . . 189
5.3.1. Thermodynamics of primary nucleation . . . . . . . . . . . . . . . . 190
5.3.2. Nucleation and primary particle formation processes . . . . . . . . . 191
5.3.3. Secondary nucleation . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
5.4. Kinetics and mechanism of heterogeneous reactions . . . . . . . . . . . 194
5.4.1. Mechanism of heterogeneous chemical reactions . . . . . . . . . . . 194
5.4.2. Rates of heterogeneous reactions in fluid-solid systems . . . . . . . 195
5.4.3. Experimental rates of gasification reactions . . . . . . . . . . . . . . 197
5.4.4. Experimental rates of oxide and sulfide dissolution by
acid-base reactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202
5.4.5. Rates of heterogeneous chemical reactions in fluid-fluid
systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
5.4.6. Experimental rates of transfer processes . . . . . . . . . . . . . . . . 207
5.4.7. Experimental rates of gas-liquid reactions . . . . . . . . . . . . . . . 209
5.5. Reaction rates for in situ conversion of a solid particle . . . . . . . . . . 211
5.5.1. Reduction of an oxide in solid state by carbon monoxide or
hydrogen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
5.5.2. Roasting of a zinc sulfide particle . . . . . . . . . . . . . . . . . . . . 214
5.6. Heterogeneous precipitation . . . . . . . . . . . . . . . . . . . . . . . . . . 215
5.6.1. Deposition mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . 216
viii Extractive Metallurgy 1
5.6.2. Silicon deposition by heterogeneous thermal decomposition
of silane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216
5.7. Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
Chapter 6. Transport Kinetics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219
6.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219
6.1.1. Identification of the rate-limiting step . . . . . . . . . . . . . . . . . . 222
6.2. Equations of change and relationships between diffusion fluxes
and driving forces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223
6.2.1. Equations of change (in terms of the fluxes) . . . . . . . . . . . . . . 223
6.2.2. Relationships between diffusion fluxes, driving forces and
transport properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
6.3. Interphase mass or heat transport (mass and heat transfer) . . . . . . . . 227
6.3.1. Definitions of heat and mass transfer coefficients . . . . . . . . . . . 227
6.3.2. Kinetics of diffusion-controlled processes . . . . . . . . . . . . . . . 229
6.4. Mass and heat transfer coefficients . . . . . . . . . . . . . . . . . . . . . . 236
6.4.1. Mass and heat transfer (across a phase boundary) between two
semi-infinite and stagnant phases . . . . . . . . . . . . . . . . . . . . . . . . 237
6.4.2. Heat and mass transfer between a flat wall and a fluid flowing
along the flat surface in forced convection: boundary layer theory . . . . 239
6.4.3. Heat and mass transfer between particles, drops or bubbles
and a continuous fluid phase . . . . . . . . . . . . . . . . . . . . . . . . . . . 243
6.5. Overall kinetics of extraction processes under mixed control . . . . . . 247
6.5.1. Extraction process-type gasification . . . . . . . . . . . . . . . . . . . 247
6.5.2. Transfer process-type solvent extraction . . . . . . . . . . . . . . . . 249
6.5.3. Note on the rule of addition of resistances acting in series . . . . . . 250
6.6. Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
Chapter 7. Particulate Kinetics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253
7.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253
7.2. Gasification/leaching of a particle . . . . . . . . . . . . . . . . . . . . . . 254
7.2.1. Non-porous particles . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254
7.2.2. Porous particles (pellets) . . . . . . . . . . . . . . . . . . . . . . . . . 259
7.3. Heterogeneous precipitation: growth rate of the particles . . . . . . . . . 263
7.4. In situ conversion of a solid particle . . . . . . . . . . . . . . . . . . . . . 264
7.4.1. Non-porous particle: the shrinking unreacted core model . . . . . . 265
7.4.2. In situ conversion of a porous particle: the grain pellet model . . . 269
7.5. Conversion of a particle undergoing strong exo- or endothermic
chemical reactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 270
7.5.1. Exothermic chemical reactions . . . . . . . . . . . . . . . . . . . . . . 270
7.5.2. Endothermic chemical reactions . . . . . . . . . . . . . . . . . . . . . 275
Table of Contents ix
7.6. Transfer processes between two fluid phases, one phase being
dispersed (as drops or bubbles) in the second phase . . . . . . . . . . . . . . 276
7.6.1. Heat transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276
7.6.2. Mass transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277
7.6.3. Hydrogen removal from liquid steel bath by injection of inert
gas bubbles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278
7.7. Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280
Chapter 8. Electrochemical Reactions . . . . . . . . . . . . . . . . . . . . . . . 283
8.1. Overview of electrochemical processes . . . . . . . . . . . . . . . . . . . 283
8.2. Equilibrium electric potential of an elementary electrochemical
reaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285
8.2.1. Nernst equation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285
8.2.2. Electrode potentials in aqueous solutions . . . . . . . . . . . . . . . . 288
8.2.3. Equilibrium potential metal/ion EM Mz+ in molten salts . . . . . . 292
8.3. Electrochemical equilibria of metals and metalloids (Pourbaix
diagrams) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292
8.3.1. Diagram of electrochemical equilibria of water . . . . . . . . . . . . 293
8.3.2. Pourbaix diagram for metal-water systems . . . . . . . . . . . . . . . 294
8.3.3. Pourbaix diagram for the Fe, Cu and Zn-Cl-H O systems . . . . . . 300
2
8.3.4. Pourbaix diagrams for the M-NH -H O systems . . . . . . . . . . . 302
3 2
8.3.5. Pourbaix diagrams for the M-HCN-H O systems . . . . . . . . . . . 304
2
8.3.6. Pourbaix diagrams for the M-S-H O systems . . . . . . . . . . . . . 305
2
8.4. Electrochemical kinetics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306
8.4.1. Rate of an elementary electrochemical reaction: Tafel’s Law . . . . 307
8.4.2. Diffusion-controlled rate of an elementary electrochemical
reaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 312
8.4.3. Rate of a redox chemical reaction . . . . . . . . . . . . . . . . . . . . 313
8.5. Redox electrochemical reactions . . . . . . . . . . . . . . . . . . . . . . . 314
8.5.1. Cementation or displacement reaction . . . . . . . . . . . . . . . . . 315
8.5.2. Leaching (dissolution) of metals . . . . . . . . . . . . . . . . . . . . . 319
8.6. Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 322
List of Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337
Summaries of Other Volumes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 345
Preface
Extractive metallurgy is the art of extracting metals from their ores and refining
them.
This book deals with the processes, operations, technologies and processing
routes of extractive metallurgy, i.e. the (production) extraction of metals from ores,
concentrates (enriched ores), scraps and other sources and their refining to liquid
metals before casting or to solid metals.
In many books dealing with metallurgy, the introduction starts by recalling the
steps of the progress of metallurgy. These steps, according to and since Lucrèce, are
identical to those of human progress: the copper age, the bronze age, the iron age,
the silicon age1. According to Mohen2, the considerable role attributed to the three
principal metals in the development of human societies must not be overstressed or
overvalued. It is nonetheless true that “metallurgy is the most advanced prehistoric
manifestation of the mastery of natural resources” (Mohen). Extracting copper from
its ore dates back to the middle of the fifth millennium before our age and extracting
iron from its ore dates from the beginning of the second millennium before our age.
The winning (production) of metals and alloys today is still one of the basic
industries of the transformation of matter. Metals and alloys still are essential
resources for metallic, mechanic, electromagnetic, electric and even electronic
industries (silicon is treated as a metal).

1 S.L. SASS, The Substance of Civilization: Materials and Human History from the Stone Age
to the Age of Silicon, Arcade Publishing, 1999.
2 J.P. MOHEN, Métallurgie préhistorique, Masson, Paris, 1990.
xii Extractive Metallurgy 1
This industry is characterized by:
– Production (of primary metal) ranging from 1,345 million tons (Mt) of steel a
year to 138,000 tons of titanium, in 20073.
Steel Aluminum Copper Zinc Lead Nickel Magnesium Titanium
1,345 38 15.6 10.6 7.0 1.66 0.79 0.138
Table 1. World Metal Production in 2007
– Very high growth rates in the years 1950 to 1973, and again since 2000. The
production of steel was 200 million tons in 1950. The production of aluminum
increased from 2 million tons in 1950 to 10 million tons in 1973, reaching
38 million tons in 2007. If in developed countries the growth in terms of tonnage has
strongly slowed in recent decades, this is due to a smaller consumption of these
products owing to the increase in mechanical and physical properties of the
materials and parts forged from these materials, thus requiring less material for the
same usage. However the annual production of steel in China increased from
182 million tons in 2002 to 489 million tons in 20074.
– Production costs varying by a factor of 20 to 25 between steel and titanium.
The three principal costs in metal production are investment, ore and energy
consumption. The energy consumption is about 20 GJ/ton of steel, 80 GJ/ton of
aluminum and 160 GJ/ton of titanium. Hence the permanent research into
improvements of the processes or operations and/or the development of new
processes.
– Very high recycling rates. Recycled steel represents 46% of iron sources in
worldwide steel production. The “electric furnace processing route” produces 35%
of steel. It uses 75% less energy than the integrated route. The recycling rate of
aluminum represents 25% of total production and the energy consumption from
recycled aluminum represents 5% (energy reflow) of energy consumption from the
ore. The production of primary zinc is 7.4 million tons and from recycled zinc is
2.1 million tons. In the case of lead, the production from recycled lead is greater
than 50%.
– Very high quality products with degrees of purity (i.e. contents of harmful
impurities) for the finished products, comparable to the purity of materials for
electronics and with very narrow concentration ranges of the alloying elements, to
obtain physical or mechanical properties with very small dispersions. For metal
castings reaching 300 tons, steel grades with carbon content of less than 25 ppm,

3 US Geological Survey, Minerals Commodity Summaries and Minerals Yearbook, 2007.
4 Source: IISI (International Iron and Steel Institute).