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Essential Readings in Light Metals, Volume 2, Aluminum Reduction Technology

Essential Readings in Light Metals, Volume 2, Aluminum Reduction Technology

Geoff Bearne (Editor), Marc Dupuis (Editor), Gary Tarcy (Editor)

ISBN: 978-1-118-64780-6

Apr 2013

1144 pages




Landmark research findings and reviews in aluminum reduction technology

Highlighting some of the most important findings and insights reported over the past five decades, this volume features many of the best original research papers and reviews on aluminum reduction technology published from 1963 to 2011. Papers have been organized into seven themes:

1. Fundamentals

2. Modeling

3. Design

4. Operations

5. Control

6. Environmental

7. Alternative processes

The first six themes deal with conventional Hall-Héroult electrolytic reduction technology, whereas the last theme features papers dedicated to nonconventional processes. Each section begins with a brief introduction and ends with a list of recommended articles for further reading, enabling researchers to explore each subject in greater depth.

The papers for this volume were selected from among some 1,500 Light Metals articles. Selection was based on a rigorous review process. Among the papers, readers will find breakthroughs in science as well as papers that have had a major impact on technology. In addition, there are expert reviews summarizing our understanding of key topics at the time of publication.

From basic research to advanced applications, the articles published in this volume collectively represent a complete overview of aluminum reduction technology. It will enable students, scientists, and engineers to trace the history of aluminum reduction technology and bring themselves up to date with the current state of the technology.

Preface xvii

Lead Editors xxi

Editorial Team xxiii

Part 1: Fundamentals

Section Introduction 1


Principles of Aluminum Electrolysis 3
W. Haupin

Bath Properties

The Solubility of Aluminum in Cryolite Melts 12
K. Yoshida and E. Dewing

Viscosity of Molten NaF-AlF3-Al203-CaF2 Mixtures: Selecting and Fitting Models in a Complex System 19
T. Hertzberg, K. Torklep, and H. 0ye

On the Solubility of Aluminium Carbide in Cryolitic Melts —Influence on Cell Performance 25
R. 0degard, A. Sterten, and J. Thonstad

Liquidus Curves for the Cryolite - A1F3 - CaF2 - A1203 System in Aluminum Cell Electrolytes 33
R. Peterson and A. Tabereaux

The Solubility of Aluminium in Cryolitic Melts 39
R. 0degard, A. Sterten, and J. Thonstad

Dissolved Metals in Cryolitic Melts 49
X. Wang, R. Peterson, and N. Richards

Electrical Conductivity of Cryolitic Melts 57
X. Wang, R. Peterson, and A. Tabereaux

Electrical Conductivity of Molten Cryolite-Based Mixtures Obtained with a Tube-type Cell Made of Pyrolytic Boron Nitride 65
J. Hives, J. Thonstad, A. Sterten, and P. Fellner

Liquidus Temperature and Alumina Solubility in the System Na3-AlF6-AlF3-LiF-CaF2-MgF2 73
A.Solheim, S. Rolseth, E. Skybakmoen, L. Stoen, A. Sterten, and T. Store

Unconventional Bath

Lithium-Modified Low Ratio Electrolyte Chemistry for Improved Performance in Modern Reduction Cells 83
A. Tabereaux, T.Alcorn, and L. Trembley

Production of Aluminum with Low Temperature Fluoride Melts 89
T. Beck

Alumina Dissolution

The Structure of Alumina Dissolved in Cryolite Melts 96
H. Kvande

The Dissolution of Alumina in Cryolite Melts 105
J. Thonstad, A. Solheim, S. Rolseth, and O. Skar

Further Studies of Alumina Dissolution Under Conditions Similar to Cell Operation 112
G. Kuschel and B. Welch

Anode Effect Mechanism

Studies on Anode Effect in Aluminium Electrolysis 119
Q. Zhu-Xian, W. Ching-Bin, and C. Ming-Ji

Direct Observation of the Anode Effect by Radiography 127
T. Utigard, J. Toguri, and S. Ip

On the Anode Effect in Aluminum Electrolysis 131
J. Thonstad, T. Utigard, and H. Vogt

Energy and Voltage Breakdown

Anodic Overpotentials in the Electrolysis of Alumina 139
B. Welch and N. Richards

Cathode Voltage Loss in Aluminum Smelting Cells 147
W. Haupin

Interpreting the Components of Cell Voltage 153
W. Haupin

Thermodynamics of Electrochemical Reduction of Alumina 160
W. Haupin and H. Kvande

Field Study of the Anodic Overvoltage inPrebaked Anode Cells 166
H. Gudbrandsen, N. Richards, S. Rolseth, and J. Thonstad

Current Efficiency

Current Efficiency and Alumina Concentration 172
B. Lillebuen and T. Mellerud

Continuous Measurement of Current Efficiency, by Mass Spectrometry, on a 280 KA Prototype Cell 177
M. Leroy, T. Pelekis, and J. Jolas

The Influence of Dissolved Metals in Cryohtic Melts on Hall Cell Current Inefficiency 181
R. Peterson and X. Wang

The Interaction Between Current Efficiency and Energy Balance in Aluminium Reduction Cells 188
F. Stevens, W. Zhang, M. Taylor, and J. Chen

A Laboratory Study of Current Efficiency in Cryolitic Melts 195
P. Solli, T. Haarberg, T. Eggen, E. Skybakmoen, and A. Sterten

Current Efficiency Studies in a Laboratory Aluminium Cell Using the Oxygen Balance Method 204
M. Dorreen, M. Hyland, and B. Welch

Current Efficiency inPrebake and Soderberg Cells 211
G. Tarcy and K. Torklep

Physical Properties

Bath/Freeze Heat Transfer Coefficients: Experimental Determination and Industrial Application 217
M. Taylor and B. Welch

Sludge in Operating Aluminium Smelting Cells 222
P. Geay, B. Welch, and P. Homsi

The Behaviour of Phosphorus Impurities in Aluminium Electrolysis Cells 229
E. Haugland, G. Haarberg, E. Thisted, and J. Thonstad

Cell Studies

See-through Hall-Heroult Cell 234
W. Haupin and W. McGrew

Metal Pad Velocity Measurements in Prebake and Soderberg Reduction Cells 240
A. Tabereaux and R. Hester

Metal Pad Velocity Measurements by the Iron Rod Method 251
B. Bradley, E. Dewing, and J. Rogers

On the Bath Flow, Alumina Distribution and Anode Gas Release in Aluminium Cells 257
O. Kobbeltvedt and B. Moxnes

Bubble Noise from Soderberg Pots 265
M. Jensen, T. Pedersen, and K. Kalgraf

Recommended Reading 269

Part 2: Modeling

Section Introduction 273

Thermal Balance

Simulation of Thermal, Electric and Chemical Behaviour of an Aluminum Cell on a Digital Computer 275
A. Ek and G. Fladmark

Estimation of Frozen Bath Shape in an Aluminum Reduction Cell by Computer Simulation 279
Y. Arita, N. Urata, and H. Ikeuchi

A Water-Model Study of the Ledge Heat Transfer in an Aluminium Cell 286
J. Chen, C. Wei, and A. Ackland

Computation of Aluminum Reduction Cell Energy Balance Using ANSYS® Finite Element Models 294
M. Dupuis

Thermo-Electric Design of a 400 kA Cell Using Mathematical Models: A Tutorial 303
M. Dupuis

A Modelling Approach to Estimate Bath and Metal Heat Transfer Coefficients 309
D. Severn and V. Gusberti

MHD and Stability

Computer Model for Magnetic Fields in Electrolytic Cells Including the Effect of Steel Parts 315
T. Sele

The Effect of Some Operating Variables on Flow in Aluminum Reduction Cells 322
E. Tarapore

Magnetics and Metal Pad Instability 330
N. Urata

Stability of Aluminum Cells - A New Approach 336
R. Moreau and D. Ziegler

Analysis of Magnetohydrodynamic Instabilities in Aluminum Reduction Cells 342
M. Segatz and C. Droste

Magnetohydrodynamic Effect of Anode Set Pattern on Cell Performance 352
M. Segatz, C. Droste, and D. Vogelsang

Stability of Interfacial Waves in Aluminium Reduction Cells 359
P. Davidson and R. Lindsay

Using a Magnetohydrodynamic Model to Analyze Pot Stability in Order to Identify an Abnormal Operating Condition 367
J. Antille and R. von Kaenel

Wave Mode Coupling and Instability in the Internal Wave in Aluminum Reduction Cells 373
N. Urata

Comparison of Various Methods for Modeling the Metal-Bath Interface 379
D. Severo, V. Gusberti, A. Schneider, E. Pinto, and V. Potocnik

Bubbles and Bath Flow

Physical Modelling of Bubble Behaviour and Gas Release from Aluminum Reduction Cell Anodes 385
S. Fortin, M. Gerhardt, and A. Gesing

Coupled Current Distribution and Convection Simulator for Electrolysis Cells 396
K. Bech, S. Johansen, A. Solheim, and T. Haarberg

Effect of the Bubble Growth Mechanism on the Spectrum of Voltage Fluctuations in the Reduction Cell 402
L. Kiss and S. Poncsak

Modeling the Bubble Driven Flow in the Electrolyte as a Tool for Slotted Anode Design Improvement 409
D. Severo, V. Gusberti, E. Pinto, and R. Moura


Planning Smelter Logistics: A Process Modeling Approach 415
I. Eick, D. Vogelsang, and A. Behrens

CFD Modeling of the Fjardaal Smelter Potroom Ventilation 421
J. Berkoe, P. Diwakar, L. Martin, B. Baxter, C. Read, P. Grover, and D. Ziegler

Heat Transfer Considerations for DC Busbars Sizing 427
A. Schneider, T. Plikas, D. Richard, and L. Gunnewiek

The Impact of Cell Ventilation on the Top Heat Losses and Fugitive Emissions in an Aluminium Smelting Cell 433
H. Abbas, M. Taylor, M. Farid, and J. Chen

Mathematical Modelling of Aluminum Reduction Cell Potshell Deformation 439
M. Dupuis

Recommended Reading 445

Part 3: Design

Section Introduction 449

New Cell Design

Development of Large Prebaked Anode Cells by Alcoa 451
G. Holmes, D. Fisher, J. Clark, and W. Ludwig

Aluminium Pechiney 280 kA Pots 457
B. Langon and P. Varin

AP 50: The Pechiney 500 kA Cell 462
C. Vanvoren, P. Homsi, J. Basquin, and T. Beheregaray

The Pot Technology Development in China 468
X. Yang, J. Zhu, and K. Sun

Cell Retrofit

VAW Experience in Smelter Modernization 474
V. Sparwald, G. Wendt, and G. Winkhaus

From HOto 175 kA: Retrofit of VAW Rheinwerk Part I: Modernization Concept 479
D. Vogelsang, I. Eick, M. Segatz, and C. Droste

From 110 to 175 kA: Retrofit of VAW Rheinwerk Part II: Construction & Operation 485
J. Ghosh, A. Steube, and B. Levenig

Productivity Increase at Soral Smelter 489
T. Johansen, H. Lange, and R. von Kaenel

Reduction Cell Technology Development at Dubai Through 20 Years 494
A. Kalban, Y. AlFarsi, and A. Binbrek

Potline Amperage Increase from 160 kA to 175 kA during One Month 500
B. Moxnes, E. Furu, O. Jakob sen, A. Solbu, and H. Kvancle

AP35: The Latest High Performance Industrially Available New Cell Technology 506
C. Vanvoren, P. Homsi, B. Feve, B. Molinier, and Y. di Giovanni

Tomago Aluminium AP22 Project 512
L. Fiot, C. Jamey, N. Backhouse, and C. Vanvoren

Development of D18 Cell Technology at Dubai 518
D. Whitfield, A. Said, M. Al-Jallaf, and A. Mohammed

New Cathodes in Aluminum Reduction Cells 523
N. Feng, Y. Tian, J. Peng, Y. Wang, X. Qi, and G. Tu


Dimensioning of Cooling Fins for High-Amperage Reduction Cells 527
I. Eick and D. Vogelsang

Satisfying Financial Institutions for Major Capital Projects 534
J. Heintzen and R. Harrison

Development and Deployment of Slotted Anode Technology at Alcoa 539
X. Wang, G. Tarcy, S. Whelan, S. Porto, C. Ritter, B. Ouellet, G. Homley, A. Morphett, G. Proulx,
S. Lindsay, andJ. Bruggeman

Innovative Solutions to Sustainability in Hydro 545
H Lange, N. Holt, H Linga, and L. Solli

Recommended Reading 551

Part 4: Operations

Section Introduction 553

Anode Change

Current Pickup and Temperature Distribution in Newly Set Prebaked Hall-Heroult Anodes 555
R. 0degard, A. Solheim, and K. Thovsen

Thermal Effects by Anode Changing in Prebake Reduction Cells 562
F. Aune, M. Bugge, H. Kvande, T. Ringstad, and S. Rolseth

Material Issues

Considerations in the Selection of Alumina for Smelter Operation 569
A. Archer

Alumina Transportation to Cells 574
I. Stankovich

Study of Alumina Behavior in Smelting Plant Storage Tanks 581
H Hsieh

New Aerated Distribution (ADS) and Anti Segregation (ASS) Systems for Alumina 590
M. Karlsen, A. Dyr0y, B. Nagell, G. Enstad, and P. Hilgraf

Beryllium in Pot Room Bath 596
S. Lindsay and C. Dobbs

Hard Gray Scale 602
N. Dando and S. Lindsay

Aluminum Fluoride — A Users Guide 608
S. Lindsay

Anode Cover and Crust

Crusting Behavior of Smelter Aluminas 613
D. Townsend and L. Boxall

On Alumina Phase Transformation and Crust Formation in Aluminum Cells 622
R. Oedegard, S. Roenning, S. Rolseth, and J. Thonstad

Heat Transfer, Thermal Conductivity, and Emissivity of Hall-Heroult Top Crust 630
K. Rye, J. Thonstad, and X. Liu

Improving Anode Cover Material Quality at Nordural— Quality Tools and Measures 639
H. Gudmundsson

Operational Improvement

Appraisal of the Operation of Horizontal-Stud Cells with the Addition of Lithium Flouride 645
K. Mizoguchi and K. Yuhki

Technical Results of Improved Soederberg Cells 652
H. Hosoi, M. Sugaya, and S. Tosaka

Strategies for Decreasing the Unit Energy and Environmental Impact of Hall-Heroult Cells 659
N. Richards

Operational and Control Improvements in Reduction Lines at Aluminium Delfzijl 669
M. Stam, M. Taylor, J. Chen, and S. van Dellen

Power Modulation and Supply Issues

Modeling Power Modulation 674
M. Dupuis

Smelters in the EU and the Challenge of the Emission Trading Scheme 679
H. Kruse

Challenges in Power Modulation 683
D. Eisma and P. Pate I

Cell Start-up and Restart

Hibernating Large Soderberg Cells 689
N. Sundaram

Thermal Bake-Out of Reduction Cell Cathodes-Advantages and Problem Areas 694
W. Richards, P. Young, J. Keniry, and P. Shaw

The Economics of Shutting and Restarting Primary Aluminium Smelting Capacity 699
K. Driscoll

Brazil 2001 Energy Crisis -The Albras Approach 707
H. Dias

Potline Startup with Low Anode Effect Frequency 712
W. Kristensen, G. Hoskuldsson, and B. Welch

Cell Preheat/Start-up and Early Operation 718
K. Rye

Loss in Cathode Life Resulting from the Shutdown and Restart of Potlines at Aluminum Smelters 723
A. Tabereaux

Simultaneous Preheating and Fast Restart of 50 Aluminium Reduction Cells in an Idled Potline 729
A. Mulder, A. Folkers, M. Stam, and M. Taylor

Recommended Reading 735

Part 5: Control

Section Introduction 737


Overview of Process Control in Reduction Cells and Potlines 739
P. Homsi, J. Peyneau, and M. Reverdy

Alumina Control

A Demand Feed Strategy for Aluminium Electrolysis Cells 747
K. Robilliard and B. Rolofs

Design Considerations for Selecting the Number of Point Feeders in Modern Reduction Cells 752
M. Walker, J. Pur die, N. Wai-Poi, B. Welch, and J. Chen

Pseudo Resistance Curves for Aluminium Cell Control - Alumina Dissolution and Cell Dynamics 760
H. Kvande, B. Moxnes, J. Skaar, and P. Solli

Aiming For Zero Anode Effects 767
W. Haupin and E. Seger

Reduction of CF4 Emissions from the Aluminum Smelter in Essen 774
M. Iffert, J. Opgen-Rhein, and R. Ganther

The Initiation, Propagation and Termination of Anode Effects in Hall-Heroult Cells 782
TMS, G. Tarcy, and A. Tabereaux

Heat Balance Control

Operation of 150 kAPrebaked Furnaces with Automatic Voltage Control 786
R. Bacchiega, A. Innocenti, M. Holzmann, and B. Panebianco

Bath Chemistry Control System 798
D. Salt

The Liquidus Enigma 804
W. Haupin

Control of Bath Temperature 808
P. Entner

Noise Classification in the Aluminum Reduction Process 812
L. Banta, C. Dai, and P. Biedler

Increased Current Efficiency and Reduced Energy Consumption at the TRIMET Smelter Essen Using 9 Box Matrix Control 817
T. Rieck, M. Iffert, P. White, R. Rodrigo, and R. Kelchtermans

A Nonlinear Model Based Control Strategy for the Aluminium Electrolysis Process 825
S. Kolas and S. Wasbo

Probes and Sensors

Bath and Liquidus Temperature Sensor for Molten Salts 830
P. Verstreken and S. Benninghoff

Anode Signal Analysis — The Next Generation in Reduction Cell Control 838
J. Keniry and E. Shaidulin

Alcoa STARprobe™ 844
X. Wang, B. Hosier, and G. Tarcy

Recommended Reading 851

Part 6: Environmental

Section Introduction 855

HF and Other Gaseous Emission

A Study of Factors Affecting Fluoride Emission from 10,000 Ampere Experimental Aluminum Reduction Cells 857
J. Henry

The Characterisation of Aluminium Reduction Cell Fume 865
L. Less and J. Waddington

Factors Affecting Fluoride Evolution from Hall-Heroult Smelting Cells 870
W. Wahnsiedler, R. Danchik, W. Haupin, D. Backenstose, and J. Colpitts

A Study of the Equilibrium Adsorption of Hydrogen Fluoride on Smelter Grade Aluminas 879
W. Lamb

The Role and Fate of S02inthe Aluminium Reduction Cell Dry Scrubbing Systems 889
W. Lamb

Sulphur Containing Compounds in the Anode Gas from Aluminium Cells, A Laboratory Investigation 898
R. Oedegard, S. Roenning, A. Sterten, and J. Thonstad

Mathematical Model of Fluoride Evolution from Hall-Heroult Cells 903
W. Haupin and H. Kvande

Factors Influencing Cell Hooding and Gas Collection Efficiencies 910
M. Karlsen, V. Kielland, H Kvande, and S. Vestre

Sulfur and Fluorine Containing Anode Gases Produced during Normal Electrolysis and Approaching an Anode Effect 918
M. Dorreen, D. Chin, J. Lee, M. Hyland, and B. Welch

Understanding the Effects of the Hydrogen Content of Anodes on Hydrogen Fluoride Emissions from Aluminium Cells... 924
E. Patterson, M. Hyland, V. Kielland, and B. Welch

Effect of Open Holes in the Crust on Gaseous Fluoride Evolution from Pots 930
M. Slaugenhaupt, J. Bruggeman, G. Tarcy, and N. Dando

Alumina Structural Hydroxyl as a Continuous Source of HF 936
M. Hyland, E. Patterson, and B. Welch

Investigation of Solutions to Reduce Fluoride Emissions from Anode Butts and Crust Cover Material 942
G. Girault, M. Faure, J. Bertolo, S. Massambi, and G. Bertran

Gas Capture and Treatment

Global Considerations of Aluminium Electrolysis on Energy and the Environment 948
R. Huglen and H. Kvande

The Surface Chemistry of Secondary Alumina from the Dry Scrubbing Process 956
A. Gillespie, M. Hyland, and J. Metson

S02 Emission Control in the Aluminium Industry 962
S. Strommen, E. Bjornstad, and G. Wedde

Reduction of HF Emissions from the TRIMET Aluminum Smelter (Optimizing Dry Scrubber Operations and Its Impact on Process Operations) 968
M. Lffert, M. Kuenkel, M. Skyllas-Kazacos, and B. Welch

Handling C02EQ from an Aluminum Electrolysis Cell 975
O. Lorentsen, A. Dyroy, and M. Karlsen

Dry Scrubbing for Modern Pre-Bake Cells 981
S. Lindsay and N. Dando

Pot Gas Heat Recovery and Emission Control 987
A. Sorhuus and G. Wedde

The Applicability of Carbon Capture and Sequestration in Primary Aluminium Smelters 993
S. Broek and S. Save

Material Issues

Dusting Properties of Industrial Aluminas 999
P. Ravn and A. Windfeldt

Perfluorocarbon (PFC) Emissions

Evaluation of Fluorocarbon Emissions from the Aluminum Smelting Process 1007
R. Roberts and P. Ramsey

Perfluorocarbon (PFC) Generation at Primary Aluminum Smelters 1015
B. LeberJr., A. Tabereaux, J. Marks, B. Lamb, T. Howard, R. Kantamaneni, M. Gibbs, V. Bakshi, and E. Dolin

Factors Affecting PFC Emissions from Commercial Aluminum Reduction Cells 1024
J. Marks, A. Tabereaux, D. Rape, V. Bakshi, and E. Dolin

Protocol for Measurement of Tetrafluoromethane and Hexafluoroethane fromPrimary Aluminum Production 1032
J. Marks, R. Kantamaneni, D. Rape, and S. Rand

On Continuous PFC Emission Unrelated to Anode Effects 1037
W. Li, Q. Zhao, J. Yang, S. Qiu, X. Chen, J. Marks, and C. Bayliss

Recommended Reading 1043

Part 7: Alternative Processes

Section Introduction 1047


Impact of Alternative Processes for Aluminium Production on Energy Requirements 1049
K Grjotheim and B. Welch

Alternate Smelting Processes for Aluminum 1056
C. Cochran


Technoeconomic Assessment of the Carbothermic Reduction Process for Aluminum Production 1070
W. Choate and J. Green

Solid State Carbothermal Reduction of Alumina 1076
D. Liu, G. Zhang, J. Li, and O. Ostrovski


Production of Aluminum-Silicon Alloys from Sand and Clay in Hall Cells 1082
A. Tabereaux and C. McMinn

Bench Scale Electrolysis of Alumina in Sodium Fluoride-Aluminum Fluoride Melts Below 900°C 1089
W. Sleppy and C. Cochran

Electrolysis of Alumina in a Molten Salt at 760°C 1095
A. LaCamera

Aluminum Reduction via Near Room Temperature Electrolysis in Ionic Liquids 1100
B. Wu, R. Reddy, and R. Rogers

Recommended Reading 1107

Author Index 1109