Light Metals 2011

Edited by STEPHEN J. LINDSAY
TMS2011 14oth Annual Meeting & Exhibition
Edited by Stephen J. Lindsay
Proceedings of the technical sessions presented by the TMS Aluminum Committee
at the TMS 2011 Annual Meeting & Exhibition, San Diego, California, USA February 27-March 3, 2011
Editor Stephen J. Lindsay
Chemistry and Materials Science: Professional
Copyright© 2016 by The Minerals, Metals, & Materials Society Published by Springer International Publishers, Switzerland, 2016 Reprint of the original edition published by John Wiley & Sons, Inc., 2011,978-1-11802-935-0
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Preface ........................................................................................................................................................................xxi About the Editor .......................................................................................................................................................xxiii Program Organizers...................................................................................................................................................xxv Aluminum Committee ..............................................................................................................................................xxxi
Resource Utilization of High-sulfur Bauxite of Low-median Grade in Chongqing China..........................................19 J. Yin, W. Xia, and M. Han
Development of Bauxite and Alumina Resources in the Kingdom of Saudi Arabia ...................................................23 A. Al-Dubaisi
Digestion Studies on Central Indian Bauxite...............................................................................................................29 P. Raghavan, N. Kshatriya, and Dasgupta
Effects of Roasting Pretreatment in Intense Magnetic Field on Digestion Performance of Diasporic Bauxite...........33 Z. Ting-an, D. Zhihe, L. Guozhi, L. Yan, D. Juan, W. Xiaoxiao, and L. Yan
Bayer Process I
Influence of Solid Concentration, Particle Size Distribution, Ph And Temperature on Yield Stress of Bauxite Pulp ............................................................................................................................................................47 C. Barbato, M. Nele, and S. França
A New Method for Removal Organics in the Bayer Process.......................................................................................51 B. Yingwen, L. Jungi, S. Mingliang, and Z. Fei
Alunorte Expansion 3 - The New Lines Added to Reach 6.3 Million Tons per Year .................................................57 D. Khoshneviss, L. Corrêa, J. Ribeiro Alves Filho, H. Berntsen, and R. Carvalho
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One Green Field Megaton Grade Large Alumina Refinery with Successful Engineering & Operation Experience...63 L. Xianqing, and Y. Xiaoping
Advanced Process Control in the Evaporation Unit ....................................................................................................69 C. Kumar, U. Giri, R. Pradhan, T. Banerjee, R. Saha, and P. Pattnaik
Red Mud
Session Chairs .............................................................................................................................................................79
Application of Nanofiltration Technology to Improve Sea Water Neutralization of Bayer Process Residue .............81 K. Taylor, M. Mullett, L. Fergusson, H. Adamson, and J. Wehrli
Caustic and Alumina Recovery from Bayer Residue ..................................................................................................89 S. Gu
Production of Ordinary Portland Cement( OPC) from NALCO Red Mud..................................................................97 C. Mishra, D. Yadav, M. Alli, and P. Sharma
Recovery of Metal Values from Red Mud.................................................................................................................103 P. Raghavan, N. Kshatriya, and K. Wawrynink
Reductive Smelting of Greek Bauxite Residues for Iron Production ........................................................................113 A. Xenidis, C. Zografidis, I. Kotsis, and D. Boufounos
Precipitation, Calcination and Properties
Pressure Calcination Revisited ..................................................................................................................................131 F. Williams, and C. Misra
Physical Simulation and Numerical Simulation of Mixing Performance in the Seed Precipitation Tank with a Improved Intermig Impeller ......................................................................................................................................145 Z. Ting-an, L. Yan, W. Shuchan, Z. Hongliang, Z. Chao, Z. Qiuyue, D. Zhihe, and L. Guozhi
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Significant Improvement of Energy Efficiency at Alunorte's Calcination Facility ...................................................157 M. Missalla, H. Schmidt, J. Ribeiro, and R. Wischnewski
Attrition of Alumina in Smelter Handling and Scrubbing Systems...........................................................................163 S. Lindsay
Energy and Environment
Alunorte Global Energy Efficiency ...........................................................................................................................179 A. Monteiro, R. Wischnewski, C. Azevedo, and E. Moraes
Opportunities for Improved Environmental Control in the Alumina Industry ..........................................................185 R. Mimna, J. Kildea, E. Phillips, W. Carlson, B. Keiser, and J. Meier
Alumina Refinery Wastewater Management: When Zero Discharge Just Isn’t Feasible… ......................................191 L. Martin, and S. Howard
High Purity Alumina Powders Extracted from Aluminum Dross by the Calcining-Leaching Process .....................197 L. Qingsheng, Z. Chunming, F. Hui, and X. Jilai
Effect of Calcium/Aluminium Ratio on MgO Containing Calcium Aluminate Slags...............................................201 W. Bo, S. Hui-Lan, G. Dong, and B. Shi-Wen
Study on Extracting Aluminum Hydroxide from Reduction Slag of Magnesium Smelting by Vacuum Aluminothermic Reduction .......................................................................................................................................205 W. Yaowu, F. Naixiang, Y. Jing, H. Wenxin, P. Jianping, D. Yuezhong, and W. Zhihui
Application of Thermo-gravimetric Analysis for Estimation of Tri-hydrate Alumina in Central Indian Bauxites-An Alternative for Classical Techniques.........................................................................................................................211 Y. Ramana, and R. Patnaik
Determination of Oxalate Ion in Bayer Liquor Using Electrochemical Method .......................................................215 S. Turhan, B. Usta, Y. Sahin, and O. Uysal
Alternative Alumina Sources - Poster Session
Session Chairs ...........................................................................................................................................................219
The Effect of Ultrasonic Treatment on Alumina Leaching from Calcium Aluminate Slag ......................................221 S. Hui-lan, W. Bo, G. Dong, Z. Xue-zheng, and B. Shi-wen
Theory and Experiment on Cooling Strategy during Seeded Precipitation ...............................................................227 Z. Liu, W. Chen, and W. Li
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Extraction of Alumina from Red Mud by Divalent Alkaline Earth Metal Soda Ash Sinter Process.........................231 S. Meher, A. Rout, and B. Padhi
Dissolution Kinetics of Silicon from Sintering Red Mud in Pure Water...................................................................237 X. Li, K. Huang, and H. Zhu
The Effect of Cooling Rate on the Leachability of Calcium Aluminate Slags ..........................................................241 W. Bo, S. Hui-lan, Z. Xue-zheng, and B. Shi-wen
Preparing Polymerized Aluminum-ferrum Chloride with Red Mud .........................................................................245 L. Guilin, Y. Haiyan, and B. Shiwen
Adsorption of Polyethylene Glycol at the Interface of Dicalcium Silicate - Sodium Aluminate Solution ................251 Y. Haiyan, X. Pan, Z. Lu, and T. Ding
Production of Hematite Ore from Red Mud ..............................................................................................................255 P. Raghavan, N. Kshatriya, and K. Wawrynink
Session Chairs ...........................................................................................................................................................261
HF Measurements Inside an Aluminium Electrolysis Cell........................................................................................263 K. Osen, T. Aarhaug, A. Solheim, E. Skybakmoen, and C. Sommerseth
LasIRTM-R - The New Generation RoHS-Compliant Gas Analyzers Based on Tunable Diode Lasers ..................269 J. Gagne, J. Pisano, A. Chanda, G. Mackay, K. Mackay, and P. Bouchard
Use of Spent Potlining (SPL) in Ferro Silico Manganese Smelting ..........................................................................275 P. vonKrüger
Reduction of PFC Emissions at Pot Line 70 kA of Companhia Brasileira de Alumínio...........................................281 H. Santos, D. Melo, J. Calixto, J. Santos, and J. Miranda
Towards Redefining the Alumina Specifications Sheet - The Case of HF Emissions...............................................285 L. Perander, M. Stam, M. Hyland, and J. Metson
Design of Experiment to Minimize Fluoride and Particulate Emissions at Alumar ..................................................291 E. Batista, P. Miotto, E. Montoro, and L. Souza
Innovative Distributed Multi-Pollutant Pot Gas Treatment System ..........................................................................295 G. Wedde, O. Bjarno, and A. Sorhuus
Fluoride Emissions Management Guide (FEMG) for Aluminium Smelters .............................................................301 N. Tjahyono, Y. Gao, D. Wong, W. Zhang, and M. Taylor
Bayer Process Chemistry and Alumina Quality I
Session Chairs ...........................................................................................................................................................307
On Continuous PFC Emission Unrelated to Anode Effects ......................................................................................309 X. Chen, W. Li, J. Marks, Q. Zhao, J. Yang, S. Qiu, and C. Bayliss
Monitoring Air Fluoride Concentration around ALUAR Smelter in Puerto Madryn (Chubut Province, Argentina)....................................................................................................................................315 J. Zavatti, C. Moreno, J. Lifschitz, and G. Quiroga
Reduction of Anode Effect Duration in 400kA Prebake Cells ..................................................................................319 W. Zhang, D. Wong, M. Gilbert, Y. Gao, M. Dorreen, M. Taylor, A. Tabereaux, M. Soffer, X. Sun, C. Hu, X. Liang, H. Qin, J. Mao, and X. Lin
Sustainable Anode Effect Based Perfluorocarbon Emission Reduction....................................................................325 N. Dando, L. Sylvain, J. Fleckenstein, C. Kato, V. Van Son, and L. Coleman
Towards Eliminating Anode Effects..........................................................................................................................333 A. Al Zarouni, B. Welch, M. Mohamed Al-Jallaf, and A. Kumar
Particulate Emissions from Electrolysis Cells ...........................................................................................................345 H. Gaertner, A. Ratvik, and T. Aarhaug
Investigation of Solutions to Reduce Fluoride Emissions from Anode Butts and Crust Cover Material ..................351 G. Girault, M. Faure, J. Bertolo, S. Massambi, and G. Bertran
PFC Survey in Some Smelters of China....................................................................................................................357 W. Li, X. Chen, Q. Zhao, S. Qiu, and S. Zhang
Session Chairs ...........................................................................................................................................................367
Cells Thermal Balance
Increasing the Power Modulation Window of Aluminium Smelter Pots with Shell Heat Exchanger Technology...369 P. Lavoie, S. Namboothiri, M. Dorreen, J. Chen, D. Zeigler, and M. Taylor
New Approaches to Power Modulation at TRIMET Hamburg .................................................................................375 T. Reek
Some Aspects of Heat Transfer Between Bath and Sideledge in Aluminium Reduction Cells.................................381 A. Solheim
Towards a Design Tool for Self-heated Cells Producing Liquid Metal by Electrolysis ............................................387 S. Poizeau, and D. Sadoway
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Effects of Composition and Granulometry on Thermal Conductivity of Anode Cover Materials ............................399 H. Wijayaratne, M. Hyland, M. Taylor, A. Grama, and T. Groutso
Restart of 300kA Potlines after 5 Hours Power Failure.............................................................................................405 X. Zhao, B. Gao, H. Han, J. Liu, J. Xiao, J. Qian, J. Yan, and D. Wang
Multiblock Monitoring of Aluminum Reduction Cells Performance ........................................................................407 J. Tessier, C. Duchesne, and G. Tarcy
Session Chairs ...........................................................................................................................................................413
High Amperage Operation of AP18 pots at Karmøy.................................................................................................415 M. Bugge, H. Haakonsen, O. Kobbeltvedt, and K. Paulsen
Aluminium Smelter Manufacturing Simulation - Can These Bring Real Cost Savings? ..........................................421 M. Meijer
Simultaneous Preheating and Fast Restart of 50 Aluminium Reduction Cells in an Idled Potline - A New Soft Re- start Technique for a Pot Line ...................................................................................................................................425 A. Mulder, A. Folkers, M. Stam, and M. Taylor
SWOT Perspectives of Midage Prebaked Aluminium Smelter .................................................................................431 P. Choudhury, and A. Sharma
New Progress on Application of NEUI400kA Family High Energy Efficiency Aluminum Reduction Pot ("HEEP") Technology ................................................................................................................................................................443 D. Lu, J. Qin, Z. Ai, and Y. Ban
Improving Current Efficiency of Aged Reduction Lines at Aluminium Bahrain (Alba)...........................................449 A. Ahmed, K. Raghavendra, H. Hassan, and K. Ghuloom
Development of NEUI500kA Family High Energy Efficiency Aluminum Reduction Pot ("HEEP") Technology ..455 D. Lu, Y. Ban, X. Qi, J. Mao, Q. Yang, and H. Dong
Cells Process Control
Current Efficiency for Aluminium Deposition from Molten Cryolite-alumina Electrolytes in a Laboratory Cell....461 G. Haarberg, J. Armoo, H. Gudbrandsen, E. Skybakmoen, A. Solheim, and T. Jentoftsen
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Session Chairs ...........................................................................................................................................................465
Retrofit of a Combined Breaker Feeder with a Chisel Bath Contact Detection System to Reduce Anode Effect Frequency in a Potroom.............................................................................................................................................467 J. Verreault, R. Gariépy, B. Desgroseilliers, C. Simard, X. Delcorde, C. Turpain, S. Simard, and S. Déry
Anode Dusting from a Potroom Perspective at Nordural and Correlation with Anode Properties............................471 H. Gudmundsson
The Application of Continuous Improvement to Aluminium Potline Design and Equipment ..................................477 W. Paul
Alcoa STARprobeTM ...............................................................................................................................................483 X. Wang, B. Hosler, and G. Tarcy
Active Pot Control using Alcoa STARprobeTM.........................................................................................................491 X. Wang, G. Tarcy, E. Batista, and G. Wood
Technology & Equipment for Starting Up & Shutting Down Aluminium Pots under Full Amperage .....................497 Y. Tao, L. Meng, C. Bin, and Y. Xiaobing
Study on Solution of Al2O3 in Low Temperature Aluminum Electrolyte .................................................................503 H. Kan, N. Zhang, and X. Wang
Applications of New Structure Reduction Cell Technology in Chalco's Smelters ....................................................509 F. Liu, S. Gu, J. Wang, and H. Yang
Transport Numbers in the Molten System NaF-KF-AlF3-Al2O3 ...............................................................................513 P. Fellner, J. Hiveš, and J. Thonstad
Impact of Amperage Creep on Potroom Busbars and Electrical Insulation: Thermal-Electrical Aspects.................525 A. Schneider, D. Richard, and O. Charette
Modern Design of Potroom Ventilation ....................................................................................................................531 A. Vershenya, U. Shah, S. Broek, T. Plikas, J. Woloshyn, and A. Schneider
CFD Modelling of Alumina Mixing in Aluminium Reduction Cells ........................................................................543 Y. Feng, M. Cooksey, and P. Schwarz
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Bubble Transport by Electro-Magnetophoretic Foces at Anode Botttom of Aluminium Cells.................................549 V. Bojarevics, and A. Roy
Anodic Voltage Oscillations in Hall-Héroult Cells ...................................................................................................555 K. Einarsrud, and E. Sandnes
Session Chairs ...........................................................................................................................................................561
Electrical Conductivity of the KF-NaF- AlF3 Molten System at Low Cryolite Ratio with CaF2 Additions .............563 A. Redkin, A. Dedyukhin, A. Apisarov, P. Tin'ghaev, and Y. Zaikov
Study of ACD Model and Energy Consumption in Aluminum Reduction Cells ......................................................567 T. Yingfu, and W. Hang
Modeling of Energy Savings by Using Cathode Design and Inserts .........................................................................569 R. von Kaenel, and J. Antille
Experimental Investigation of Single Bubble Characteristics in a Cold Model of a Hall-Héroult Electrolytic Cell.........................................................................................................................................................575 S. Das, Y. Morsi, G. Brooks, W. Yang, and J. Chen
Large Gas Bubbles under the Anodes of Aluminum Electrolysis Cells ....................................................................581 A. Caboussat, L. Kiss, J. Rappaz, K. Vékony, A. Perron, S. Renaudier, and O. Martin
Initiatives to Reduction of Aluminum Potline Energy Consumption Alcoa Poços de Caldas/Brazil ........................587 A. Abreu, M. Salles, and C. Kato
Overview of High-Efficiency Energy Saving for Aluminium Reduction Cell ..........................................................591 X. Canming, and Y. Xiaobing
Cell Voltage Noise Reduction Based on Wavelet in Aluminum Reduction Cell ......................................................599 B. Li, J. Chen, X. Zhai, S. Sun, and G. Tu
Poster Session
Session Chairs ...........................................................................................................................................................603
Human Factors in Operational and Control Decision Making in Aluminium Smelters ............................................605 Y. Gao, M. Taylor, J. Chen, and M. Hautus
Aluminum Rolling
xxi
Through Process Effects on Final Al-sheet Flatness .................................................................................................625 S. Neumann, and K. Karhausen
Organizers..................................................................................................................................................................631
Session Chairs ...........................................................................................................................................................633
New Casthouse Smelter Layout for the Production of Small Non-Alloyed Ingots: Three Furnaces/Two Lines.......635 J. Berlioux, A. Bourgier, and J. Baudrenghien
Use of Process Simulation to Design a Billet Casthouse...........................................................................................641 G. Jaouen
Optimizing Scrap Reuse as a Key Element in Efficient Aluminium Cast Houses ....................................................647 T. Schmidt, J. Migchielsen, D. Ing, and H. Gräb
Implementation of an Effective Energy Management Program Supported by a Case Study ....................................653 R. Courchée
Molten Metal Safety Approach through a Network...................................................................................................657 C. Pluchon, B. Hannart, L. Jouet-Pastré, J. Mathieu, R. Wood, J. Riquet, F. Fehrenbach, G. Ranaud, M. Bertherat, and J. Hennings
Improved Monolithic Materials for Lining Aluminum Holding & Melting Furnaces...............................................663 A. Wynn, J. Coppack, T. Steele, and K. Moody
Direct Chill Casting
Effect of Cooling Water Quality on Dendrite Arm Spacing of DC Cast Billets........................................................681 S. Mohapatra, S. Nanda, and A. Palchowdhury
Mould Wall Heat Flow Mechanism in a DC Casting Mould ....................................................................................687 A. Prasad, and I. Bainbridge
Productivity Improvements at Direct Chill Casting Unit in Aluminium Bahrain (ALBA) .......................................693 A. Noor, S. Chateeriji, and A. Ahmed
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Investment Casting of Surfaces with Microholes and Their Possible Applications ..................................................705 T. Ivanov, A. Buehrig-Polaczek, U. Vroomen, C. Hartmann, A. Gillner, K. Bobzin, J. Holtkamp, N. Bagcivan, and S. Theiss
Using SEM and EDX for a Simple Differentiation of Alpha- and Beta-AlFeSi-Phases in Wrought Aluminum Billets711 M. Rosefort, C. Matthies, H. Buck, and H. Koch
Dross Formation, Control and Handling
Session Chairs ...........................................................................................................................................................717
Study of Early Stage Interaction of Oxygen with Al; Methods, Challenges and Difficulties....................................725 B. Fateh, G. Brooks, M. Rhamdhani, J. Taylor, J. Davis, and M. Lowe
Quality Assessment of Recycled Aluminium............................................................................................................731 D. Dispinar, A. Kvithyld, and A. Nordmark
The Effect of TiB2 Granules on Metal Quality ..........................................................................................................745 M. Mohamed Al-Jallaf, M. Hyland, B. Welch, A. Al Zarouni, and F. Abdullah
Thermodynamic Analysis of Ti, Zr, V and Cr Impurities in Aluminium Melt..........................................................751 A. Khaliq, M. Rhamdhani, G. Brooks, and J. Grandfield
Current Technologies for the Removal of Iron from Aluminum Alloys ...................................................................757 L. Zhang, J. Gao, and L. Damdah
Electromagnetically Enhanced Filtration of Aluminum Melts ..................................................................................763 M. Kennedy, S. Akhtar, R. Aune, and J. Bakken
Wettability of Aluminium with SiC and Graphite in Aluminium Filtration..............................................................775 S. Bao, A. Kvithyld, T. Engh, and M. Tangstad
Study of Microporosity Formation under Different Pouring Conditions in A356 Aluminum Alloy Castings..........783 L. Yao, S. Cockcroft, D. Maijer, J. Zhu, and C. Reilly
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Session Chairs ...........................................................................................................................................................791
Development of Alba High Speed Alloy...................................................................................................................803 A. Ahmed, J. Hassan, G. Martin, and K. Ghosh
Dissolution Studies of Si Metal in Liquid Al under Different Forced Convection Conditions .................................809 M. Seyed Ahmadi, S. Argyropoulos, M. Bussmann, and D. Doutre
Modification and Grain Refinement of Eutectics to Improve Performance of Al-Si Castings..................................815 M. Felberbaum, and A. Dahle
Production of Al-Ti-C Grain Refiners with the Addition of Elemental Carbon and K2TiF6 .....................................821 F. Toptan, I. Kerti, S. Daglilar, A. Sagin, O. Karadeniz, and A. Ambarkutuk
Effect of Mechanical Vibrations on Microstructure Refinement of Al-7mass% Si Alloys .......................................827 T. Tamura, T. Matsuki, and K. Miwa
Predicting the Response of Aluminum Casting Alloys to Heat Treatment................................................................831 C. Wu, and M. Makhlouf
Electrode Technology for Aluminium Production
Organizers..................................................................................................................................................................837
Operation of an Open Type Anode Baking Furnace with a Temporary Crossover ...................................................847 E. Cobo, L. Beltramino, J. Artola, J. Rey Boero, P. Roy, and J. Bigot
Recent Developments in Anode Baking Furnace Design..........................................................................................853 D. Severo, V. Gusberti, P. Sulger, F. Keller, and M. Meier
Sohar Aluminium’s Anode Baking Furnace Operation.............................................................................................859 S. Al Hosni, J. Chandler, O. Forato, F. Morales, C. Jonville, and J. Bigot
Meeting the Challenge of Increasing Anode Baking Furnace Productivity...............................................................865 F. Ordronneau, M. Gendre, L. Pomerleau, N. Backhouse, A. Berkovich, and X. Huang
Wireless Communication for Secured Firing and Control Systems in Anode Baking Furnaces ...............................871 N. Fiot, and C. Coulaud
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High Performance Sealing for Anode Baking Furnaces............................................................................................881 P. Mahieu, S. Neple, N. Fiot, I. Ofico, and M. Eufrasio
Session Chairs ...........................................................................................................................................................887
Quality and Process Performance of Rotary Kilns and Shaft Calciners ....................................................................895 L. Edwards
Sub-surface Carbon Dioxide Reaction in Anodes .....................................................................................................901 D. Ziegler
Prebaked Anode from Coal Extract (2) - Effects of the Properties of Hypercoal-coke on the Preformance of Prebaked Anodes .......................................................................................................................................................913 M. Hamaguchi, N. Okuyama, N. Komatsu, J. Koide, K. Kano, T. Shishido, K. Sakai, and T. Inoue
The New Generation of Vertical Shaft Calciner Technology....................................................................................917 J. Zhao, Q. Zhao, and Q. Zhao
Prediction of Calcined Coke Bulk Density................................................................................................................931 M. Dion, H. Darmstadt, N. Backhouse, F. Cannova, and M. Canada
Calcined Coke Particle Size and Crushing Steps Affect Its VBD Result ..................................................................937 F. Cannova, M. Canada, and B. Vitchus
Bulk Density - Overview of ASTM and ISO Methods with Examples of Between Laboratory Comparisons .........941 L. Lossius, B. Spencer, and H. Øye
Improving the Repeatability of Coke Bulk Density Testing......................................................................................947 L. Edwards, M. Lubin, and J. Marino
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Anode Quality and Rodding Processes
Session Chairs ...........................................................................................................................................................965
Characterization of a Full Scale Prebaked Carbon Anode using X-Ray Computerized Tomography.......................973 D. Picard, H. Alamdari, D. Ziegler, P. St-Arnaud, and M. Fafard
FEM Analysis of the Anode Connection in Aluminium Reduction Cells .................................................................979 S. Beier, J. Chen, M. Fafard, and H. Fortin
Development of Industrial Benchmark Finite Element Analysis Model to Study Energy Efficient Electrical Connections for Primary Aluminium Smelters..........................................................................................................985 D. Molenaar, K. Ding, and A. Kapoor
Real Time Temperature Distribution During Sealing Process and Room Temperature Air Gap Measurements of a Hall-Héroult Cell Anode ...........................................................................................................................................991 O. Trempe, D. Larouche, D. Ziegler, M. Guillot, and M. Fafard
Effects of High Temperatures and Pressures on Cathode and Anode Interfaces in a Hall-Heroult Electrolytic Cell997 L. St-Georges, L. Kiss, J. Bouchard, M. Rouleau, and D. Marceau
New Apparatus for Characterizing Electrical Contact Resistance and Thermal Contact Conductance...................1003 N. Kandev, H. Fortin, S. Chénard, G. Gauvin, M. Martin, and M. Fafard
Carbon Anode Modeling for Electric Energy Savings in the Aluminium Reduction Cell ......................................1009 D. Andersen, and Z. Zhang
Cathode Design and Operation
Development and Application of an Energy Saving Technology for Aluminum Reduction Cells .........................1023 P. Jianping, F. Naixiang, F. Shaofeng, L. Jun, and Q. Xiquan
Study of Electromagnetic Field in 300kA Aluminium Reduction Cells with Innovation Cathode Structure..........1029 B. Li, X. Zhang, S. Zhang, F. Wang, and N. Feng
Evaluation of the Thermophysical Properties of Silicon Carbide, Graphitic and Graphitized Carbon Sidewall Lining Materials Used in Aluminium Reduction Cell in Function of Temperature............................................................1035 A. Khatun, and M. Desilets
Advanced Numerical Simulation of the Thermo-Electro-Mechanical Behaviour of Hall-Héroult Cells under Electrical Preheating................................................................................................................................................1041 D. Marceau, S. Pilote, M. Désilets, L. Hacini, J. Bilodeau, and Y. Caratini
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Influence of Technological and Constructive Parameters on the Integrity of the Bottom of Aluminum Reduction Cells during Flame Preheating.................................................................................................................................1047 A. Arkhipov, G. Arkhipov, and V. Pingin
Creep Behaviors of Industrial Graphitic and Graphitized Cathodes during Modified Rapoport Tests ...................1053 W. Wang, J. Xue, J. Feng, Q. Liu, L. Zhan, H. He, and J. Zhu
Cathode Materials and Wear
Coke Selection Criteria for Abrasion Resistant Graphitized Cathodes ...................................................................1067 R. Perruchoud, W. Fischer, M. Meier, and U. Mannweiler
Determination of the Effect of Pitch-Impregnation on Cathode Erosion Rate ........................................................1073 P. Patel, Y. Sato, and P. Lavoie
Simplifying Protection System to Prolong Cell Life ...............................................................................................1079 M. Mohamed Al-Jallaf, M. Hyland, B. Welch, and A. Al Zarouni
Aluminate Spinels as Sidewall Linings for Aluminum Smelters.............................................................................1085 X. Yan, R. Mukhlis, M. Rhamdhani, and G. Brooks
Towards a Better Understanding of Carburation Phenomenon ...............................................................................1097 M. Lebeuf, M. Coulombe, B. Allard, and G. Soucy
Session Chairs .........................................................................................................................................................1109
Furan Resin and Pitch Blends as Binders for TiB2-C Cathodes ..............................................................................1117 H. Zhang, J. Hou, X. Lü, Y. Lai, and J. Li
Influence of Cobalt Additions on Electrochemical Behaviour of Ni-Fe-Based Anodes for Aluminium Electrowinning ........................................................................................................................................................1123 V. Singleton, B. Welch, and M. Skyllas-Kazacos
Effects of the Additive ZrO2 on Properties of Nickel Ferrite Cermet Inert Anode..................................................1129 X. Zhang, G. Yao, Y. Liu, J. Ma, and Z. Zhang
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Poster Session - Electrode
Session Chairs .........................................................................................................................................................1141
Influence of Ultrafine Powder on the Properties of Carbon Anode Used in Aluminum Electrolysis......................1143 X. Jin, D. Songyun, L. Jie, L. Yanqing, and L. Yexiang
Preparation NiFe2O4 Matrix Inert Anode Used in Aluminum Electrolysis by Adding Nanopowder .....................1149 Z. Zhang, G. Yao, Y. Liu, and X. Zhang
Cold Water Model Simulation of Aluminum Liquid Fluctuations Induced by Anodic Gas in New Tape of Cathode Structure Aluminum Electrolytic Cell .....................................................................................................................1155 Y. Liu, T. Zhang, Z. Dou, H. Wang, G. Lv, Q. Zhao, N. Feng, and J. He
Effects of Physical Properties of Anode Raw Materials on the Paste Compaction Behavior..................................1161 K. Azari, H. Ammar, H. Alamdari, D. Picard, M. Fafard, and D. Ziegler
Furnace Efficiency - Energy and Throughput
Organizers................................................................................................................................................................1165
Session Chairs .........................................................................................................................................................1167
Session I
Latest Trends in Post Consumer and Light Gauge Scrap Processing to include Problematic Materials such as UBC, Edge Trimming and Loose Swarf............................................................................................................................1173 F. Niedermair, and G. Wimroither
Investigation of Heat Transfer Conditions in a Reverberatory Melting Furnace by Numerical Modeling..............1179 A. Buchholz, and J. Rødseth
Oxyfuel Optimization using CFD Modeling ...........................................................................................................1185 T. Niehoff, and S. Viyyuri
New Technology for Electromagnetic Stirring of Aluminum Reverberatory Furnaces ..........................................1193 J. Herbert, and A. Peel
Evaluation of Effects of Stirring in a Melting Furnace for Aluminum....................................................................1199 K. Matsuzaki, T. Shimizu, Y. Murakoshi, and K. Takahashi
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Study on the Energy-saving Technology of Chinese Shaft Calciners .....................................................................1217 G. Lang, C. Bao, S. Gao, R. Logan, Y. Li, and J. Wu
Author Index............................................................................................................................................................1221
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PREFACE
As editor it is my pleasure to present to you these contributed proceedings of TMS’s 140th Annual Meeting and Exposition in San Diego, California. The volumes included here represent a large collective undertaking. All of it has been volunteered by the hundreds of authors, dozens of Session Chairpersons, and more than a dozen Symposium Chairpersons and Vice-Chairpersons that have created Light Metals 2011. As members we owe them all a debt of gratitude for the time and effort that they have donated.
Although our industry has faced trying times in recent years contributions to this volume from industry and There are almost twice that number of contributions from private industry, individual contributors, and research institutes combined. Many of these individuals or organizations have prepared technical papers on varied topics and across multiple symposia. Such support from our membership is what makes our annual meetings both productive and successful.
This represents the best of TMS, a professional, diverse, and growing organization that embraces and promotes both pure and applied sciences.
The volumes of Light Metals represent a large fraction of the accumulated knowledge of our industry that is in the public domain. It is often used as a primary source of reference information in the preparation of new contributions to the technical literature. Each year the wealth of information in the accumulated volumes of Light Metals grows and 2011 is no exception.
Yet, it is not enough to rest on these laurels. Our future is being shaped now by forces that our industry could not have anticipated even a decade ago. We look to grow, to include academic and industrial papers from countries, universities, and enterprises that have yet to be represented in Light Metals along with those from more established contributors. We hope to allow future authors to see further, if not from standing upon the shoulders of the giants that have preceded them in our industry.
I encourage our members to not only participate in annual meetings, but also to get actively involved. TMS committees are all composed of volunteers. Authors that have contributed in the past are most likely to contribute again. However, they, as I, would like to hear from members who may have been tempted to write a technical paper but never have done so. The strength of our organization is built upon new ideas and insights that come from all quarters of academia, research groups, and industry. New authors are always welcomed.
On behalf of the organizers for Light Metals 2011 allow me to thank the TMS staff including Marla Boots, Chris Wood, and Christina Raabe Eck and the TMS Light Metals Aluminum Committee for their support. I would also like to recognize the contributions of John A. Johnson for his guidance and for his organization of the Plenary Session celebrating 125 Years of the Hall-Héroult Aluminum Reduction Process. I especially would like to recognize the 2011 Subject Chairpersons: Mohammed Mahmood, Abdullah Habib Ahmed Ali, Dr. Alan Tomsett, Dr. James Metson, Dr. Geoffrey Brooks, Kai Karhausen and Thomas Nieoff for their dedication and leadership in preparation for our 2011 Annual Meeting.
Stephen J. Lindsay
STEPHEN J. LINDSAY LIGHT METALS 2011 EDITOR
Stephen Joseph Lindsay holds a B.S. in Chemical Engineering from Clarkson College ofTechnology and an M.A. in Applied Behavioral Science from Bastyr University's Leadership Institute of Seattle program. During his time with Alcoa he has held numerous positions with responsibilities in anode, cathode, pollution control systems, and reduction technology. He has specialized in areas including emissions control, metal purity, alumina and electrolytes. In these areas he supports Alcoa's Primary Products division worldwide. His wife, Dr. Margarita Merino de Lindsay, an author, poet, and artist in her own right is his muse. She has encouraged Steve to contribute regularly to technical literature and education, plus control of pollution. It is for her sake that the colors of Light Metals 2011 are those of Spain, her home country. A member ofTMS since 1985, Steve has regularly authored or co-authored in Light Metals. He has received the Best Paper Award in Reduction Technology in 2006 and again in 2009. He served as the Subject Chair for Reduction Technology in 2006, has instructed in various short courses, and has served under the direction of Dr. Halvor Kvande in the TMS Industrial Electrolysis Courses held since 2005. He has also authored or co-authored technical papers appear in the proceedings of the 8th and 9th Australasian Smelting Technology Conferences, the 7th and 8th International Alumina Quality Workshops, the International Committee for Study of Bauxite, Alumina, & Aluminium 2010, and the International Beryllium Research Conference 2007. Steve served on the Aluminum Association's Industrial Hygiene sub-committee for beryllium contributing to the understanding its mass balance in aluminum smelters. He has participated as an instructor on a regular basis in courses organized by the University of Auckland's Light Metals Research Centre, the University ofNew South Wales, andAlcoa's own Process Engineering Training Program. Steve is based at Alcoa's Tennessee Operations near Knoxville, Tennessee and works with Alcoa's Technology, Innovation and Center of Excellence group. His is a manager in Primary Metal's Best Practices group.
PROGRAM ORGANIZERS
ALUMINA and BAUXITE
Jim Metson graduated with PhD in Chemistry from Victoria University of Wellington, New Zealand, before taking up a position at Surface Science Western, University of Western Ontario Canada. He then moved to the University of Auckland, New Zealand, where he is a Professor, the Associate Director of the Light Metals Research Centre and Head of the Department of Chemistry. He is a Director of the New Synchrotron Group Ltd, a councillor of the Australian Institute of Nuclear Science and Engineering and chairs the Research Infrastructure Advisory Group (RIAG) for the New Zealand Government. His research interests are in materials and particularly surface science, with an emphasis on applications in the aluminium industry including alumina calcination and evolution of microstructure, smelting technology and in particular the impacts of alumina properties, and the surface science of aluminium metal. He has had more than 20 years of engagement with the aluminium industry and has been a regular participant at the Annual TMS meeting. He is a past Light Metals Award winner and has co-ordinated a course “Alumina from a Smelter Perspective” held as part of the 2004 TMS meeting !#$ Practice”.
Carlos Suarez has been associated with the alumina and bauxite industry for 30 years and has been a member of TMS since 1984. Carlos attended the Uni- versity of Oklahoma where he obtained a degree of Science in Chemical Engi- neering. He also attended the University of Phoenix where he obtained a Master in Business Administration. Carlos has been involved in all aspects of alumi- *+<+=> Alumina in the areas of Process Safety, Quality, Training and Development, Technical Sales, Plant Operations Research and Development, Commissioning and Start-Ups, Knowledge Management, Organizational Development, Tech- nology Transfer and Business Development. He has been a Process Consultant for Hatch since 2004 where he has served as process lead and project manager for different alumina plant projects around the world. Carlos has been an active member of TMS. He has contributed with several technical papers and was !#$@ course sponsored by TMS in 2008.
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ALUMINUM REDUCTION TECHNOLOGY
Mohammed Mahmood holds Master degree in Process Engineering from Strathclyde University in Scotland in 1989. He began his career with Aluminium Bahrain (ALBA) more than thirty years ago, rose through the ranks to various managerial positions, from Manager of Potlines, Manager Process & Quality Control to Manager Human Resources & Development and then to General [ [@\] _ _! ` {|} {~+ ~ {~* * +[ very often invited to speak at International Conferences both Technical and People Development related. He is the head of the Alba Community Service Committee where his role encouraged the spirit of philanthropy amongst Alba employees and enhanced kingdom wide appreciation of Alba’s corporate social responsibility initiatives. His main passion is the development of youth to become future leaders.
Abdulla Habib Ahmed, Manager Research & Development in Aluminum Bahrain (Alba), joined Alba in March of 1995 after completing his degree in ^ @ ! involved in many projects and studies to maximize Aluminum Production in Alba. He gradually climbed the success ladder of Alba hierarchy to become in charge of Metal Production as Reduction Line Superintended in year 2000. On November 2004, Abdulla completed his Master degree in University of < ! + +! @ * doing the Ph.D. in Aluminium Smelting technology and among few people in [ ! + #[ !! the innovations; process improvements in Reduction, Carbon and Casthouse in Aluminum Bahrain (Alba).
Charles “Mark” Read is Bechtel Senior Specialist – Primary Aluminium Pro- cesses. Mark is currently Bechtel’s Area Manager, Reduction for the Ma’aden “Ras Az Zawr Aluminium Smelter Project, Kingdom of Saudi Arabia. Previous * [ | | aluminium smelter projects, and technology and engineering oversight of studies for major Middle Eastern, North American and Russian aluminium Smelt- ers. Mark has 33 years experience in business and technology management in the Metals Industry, over 25 years of which were in the aluminium industry – including in-depth technical experience of Hall-Héroult cell design and operation, pre-baked carbon products processing and performance, and aluminium casting operations. Mark joined Bechtel’s Montréal-based “Aluminium Cen- tre of Excellence” in late 2003. Prior to joining Bechtel, Mark held various technology management positions with Elkem Metals, Kaiser Aluminium & ^ ^![ University, England. He holds a B.Sc. degree in Metallurgical Engineering and M.Sc. in Industrial Metallurgy.
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CAST SHOP for ALUMINUM PRODUCTION
Geoffrey Brooks, B.Eng. (RMIT), B.A. (SUT), PhD (Melb.) F. I.Eng. Aust, has been a Professor in the Faculty of Engineering and Industrial Sciences at Swinburne University of Technology since 2006, where he leads the High Temperature Processing research group. He also the leader of a cluster of researchers from Australian and New Zealand Universities focussed on improving Aluminium smelting. Previously, he was a Senior Principal Research Scientist at CSIRO (2004-2006), an Associate Professor in Materials Science and Engineering at McMaster University (2000-2004) and a Senior Lecturer at the University of Wollongong (1993-2000). In the 17 years since completing his PhD at University of Melbourne, he have published over 100 papers and run many large research projects with funding from many major companies and government agencies. He is currently active in work on dross formation in aluminium processing, controlling minor elements in the casthouse, sidewall materials in aluminium cells, development of sensors for bubbling in high temperature operations, modelling of injection processes and distribution of elements in magnesium production. He has been a key reader for Metallurgical and Materials Transactions since 1998 and is a Fellow of the Institute of Engineers (Australia). Geoff has been a member of the TMS since 1990.
> @+- * ![ (RMIT), a MSC in Mathematical Modelling (Monash University) and a PhD in Materials Science (University of Queensland). John has 25 years experience in light metals cast house research in industry and government laboratories (Rio Tinto Alcan, CASTcrc and CSIRO). He has developed new technology for aluminium and magnesium DC casting, and open mould conveyor ingot casting. He conducts problem solving and research projects, presents cast house technology training courses around the world, participates in in-house innovation workshops and conducts R&D program reviews. John has four patents and has published more than 50 conference and journal papers. He is chair of the Aus- tralasian Aluminium Casthouse Technology conference.
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ELECTRODE TECHNOLOGY for ALUMINUM PRODUCTION
Alan Tomsett has over twenty years experience in carbon anode and cathode technology. He received his BSc and PhD in Chemical Engineering from the University of New South Wales in Sydney, Australia. He joined Rio Tinto Alcan at the R&D centre in Melbourne in 1987. His activities with R&D Group have included leadership of the global and regional Carbon R&D program, provision of technical support for the RTA Australasian smelters, carbon raw material expansions. Since 2008, Alan has been the Technical Manager – Carbon for #!@[@! [ 1996. He is the coauthor of several TMS papers and is a previous TMS session chair. He is also a regular contributor to the Australasian Smelting Conference.
Barry Sadler has been involved in the Aluminium Industry for more than 25 years in a range of positions but always focusing on anode carbon technology. His career started in 1982 at the Comalco (Now Rio Tinto Alcan) Research Centre in Melbourne, Australia. In 1989 he moved to Comalco’s New Zealand Aluminium Smelter as Carbon Plant Manager. After a stint as General Manager Organisational Effectiveness for Hamersley Iron, in 1989 Barry took up the position of Technical General Manager at Comalco Aluminium’s corporate headquarters in Brisbane, Australia. Leaving Rio Tinto/Comalco in 2002 to establish Net Carbon Consulting Pty Ltd, Barry now provides consulting advice, training, and support to clients on improving plant performance, with emphasis on the practical application of statistical thinking to process management. Barry has been a regular contributor at TMS meetings for over 20 years as an author, session chairperson, and Electrodes subject organiser.
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ALUMINIUM ROLLING
Kai Friedrich Karhausen is department manager for process technology at the central Rolled Products R&D of Hydro Aluminium in Bonn, Germany. Dr. Kar- hausen earned his doctorate at the RWTH Aachen and worked in the industrial aluminum research for 15 years both in Norway and Germany. His principal work is focused on the modeling and optimization of materials behavior in in- - tions and publications. In 2003 he was awarded the Georg-Sachs-Preis of the >[>[ integrated modeling of metal forming and materials behavior.
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FURNACE EFFICIENCY - ENERGY and THROUGHPUT
Thomas Niehoff currently Head of Non Ferrous and Mining at The Linde Group, Div. Linde Gas is based in Munich, Germany. Graduated from RWTH Aachen in Germany in mechanical engineering in 1992. Thomas has 18 years experience in combustion and metallurgical applications related to industrial gases. In his global role Thomas now overlooks the R&D activities for Linde Gas. He has in depth experience in metallurgy of aluminum, iron and steel - combustion processes and emissions from combustion. He did his PhD at #!
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Past Chairperson Geoffrey Paul Hearne Rio Tinto Alcan Victoria, Australia
Hussain H. Alali Retired, Aluminum Bahrain Manama, Bahrain
Martin Iffert Trimet Aluminum AG Essen, Germany
Gilles Dufour Alcoa Canada Quebec, Canada
Pierre Le Brun Alcan Voreppe Research Center Voreppe Cedex, France
John Grandfield Granfield Technology Pty. Ltd. Victoria, Australia
Charles Mark Read Bechtel Corp. Quebec, Canada
ALUMINUM COMMITTEE 2011-2012
JOMAdvisor Pierre P. Homsi Rio Tinto Alcan
Secretary Charles Mark Read Bechtel Corp. Quebec, Canada
MEMBERS THROUGH 2012
Barry Sadler Net Carbon Consulting Pty. Ltd. Kangaroo Ground, Australia
Carlos Suarez Hatch Associates Inc. Pennsylvania, USA
CbDmUUG W@G5JD0
ORGANIZERS
Auckland, New Zealand
Pittsburgh, Pennsylvania, USA
Bauxite Resources and Utilisation
Peter-Hans ter Weer1
1TWS Services and Advice, Imkerweg 5, 1272 EB Huizen, The Netherlands; [email protected]
Keywords: Bauxite, Alumina, Project Development, Alumina Technology, Economics
1. Abstract Developing a greenfield bauxite deposit nowadays generally includes constructing an alumina refinery. Economics have resulted in ever-increasing production capacities for recently-built and future planned greenfield refineries. Rationale: economy of scale. As a result the complexity of a greenfield project has significantly increased and its capital cost has grown to several billion USD. Important consequences:
• Project owners aim at risk reduction through project financing and formation of joint ventures, further complicating project implementation.
• Globally only a limited number of (large) companies have the human and financial resources to develop greenfield bauxite & alumina projects.
• Only a limited number of engineering firms have the required skills and experience to successfully implement these mega projects.
• Only large bauxite deposits get developed.
This paper proposes an alternative development model for bauxite deposits resulting in a more efficient use of resources and a lower threshold to develop bauxite & alumina projects.
2. Bauxite Deposit Development The development of bauxite deposits is sometimes limited to the mining of bauxite for export purposes, which may or may not include drying the bauxite to a certain moisture percentage. Examples are the Boke and Kindia mines (both in Guinea), and the Bintan mine in Indonesia (now closed).
In other cases the mine supplies both a local / in-country refinery, as well as exporting bauxite, e.g. the Trombetas mine (Brazil), and the Gove and Weipa mines (both in Australia).
In most recent cases the projected greenfield development of a bauxite deposit includes directly or indirectly the construction of a captive alumina refinery. Examples: Utkal (India), GAC (Guinea), Aurukun (Australia), CAP (Brasil), Ma’aden (Saudi Arabia).
In some cases the project may be executed in two stages: a first stage of establishing the bauxite mine with (temporary) export of bauxite, and a second stage including the construction of an alumina refinery. A recent example is the Darling Range project of Bauxite Resources Ltd in Australia as stated in press releases.
How have greenfield production capacities and more specifically greenfield alumina refinery design capacities developed over time, and did this have a bearing on project implementation?
3. Alumina Refinery Capacity Evolution Overview
An alumina refinery consists of a number of unit operations such as grinding, digestion, evaporation, etc. A unit operation generally
comprises a string of equipment which together performs the desired process step, e.g. digestion with feed tank, heat exchangers, pumps, digester vessel(s), flash vessels, etc. Such a string of equipment is often referred to as a “train”, “unit” or “circuit” (e.g. digestion unit, precipitation train, mill circuit). Alumina refinery design generally takes the digestion area as plant bottleneck due to its high unit capital cost and its requirement for constant flow for optimum performance.
The design / initial refinery production capacity of greenfield projects has evolved over time from about 0.5-1.0 Mt/y alumina 25-30 years ago (e.g. Worsley, Alumar, Aughinish) to 1.4-3.3 Mt/y alumina for more recently constructed and future planned projects (e.g. Lanjigarh, Yarwun, Utkal, GAC). Figure 1 illustrates this trend.
Figure 1 – Refinery Design Capacity vs Start-up Year
Note that actual refinery production capacities increase over time as a result of de-bottlenecking, improved process efficiencies and operations performance, etc. In a paper presented at the ICSOBA 2008 conference [1] R. den Hond even suggests a doubling of design capacity by exploiting overdesign and post start-up installation of novel technology.
What has been the rationale for this trend of ever-increasing design production capacities for recently built and future planned greenfield refineries and what are its consequences?
Economy of Scale
The rationale offered for this trend is the economy of scale: an increased alumina production capacity improves the economics (NPV, IRR, VIR1) of a greenfield bauxite and alumina project2.
In the context of alumina refinery projects, economy of scale aspects may be applied to Operating Cost and Capital Cost.
1 NPV=Net Present Value; IRR=Internal Rate of Return; VIR=Value over Investment (capital efficiency) ratio. 2 Reference [2] provides an overview of bauxite & alumina project economics.
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Light Metals 2011 Edited by: Stephen J. Lindsay TMS (The Minerals, Metals & Materials Society), 2011
3.2.1 Effect on Operating Cost3
To better assess the effects of the economy of scale on Operating Cost, we should consider its major components:
• Variable costs: In $/year these costs vary with plant production, at least within certain plant production rates (typically + 10-15%), examples: bauxite, caustic soda, coal, fuel oil, lime. The overall plant on-line time of an alumina refinery with more than one train / unit / circuit, e.g. a digestion train, is higher than a plant with one train only, as a result of more flexibility in equipment operation and maintenance. The effect on plant on-line time is generally limited (indic. 0.2-0.5% abs), however may vary widely and in a specific case could be significant (>1% abs). As a result the plant operates with less interruptions and operating efficiencies (e.g. bauxite, caustic soda, energy consumption) improve, albeit generally to a limited extent (indic. 0.5-3%).
• Fixed costs: In $/year these costs do not vary with plant production, at least within certain plant production rates (typically + 100,000 t/yr), examples: labour, maintenance materials, administration, other fixed costs. This is the area on which the economy of scale potentially has the largest effect, i.e. a drop in cost per tonne of alumina produced, due to the “dilution” of “fixed” annual expenses by a larger production volume. This applies particularly to labour and other fixed costs. If the increase in production capacity includes an increase in the number of trains, this positive effect is dampened because not just the size of the equipment involved increases, but also its number. In addition, the requirements of complex and large alumina refineries may result in disproportional increases of overhead costs.
The example provided in Table 1 may illustrate the above. In this example the larger refinery capacity is based on an increase in the number of operating units in several areas, resulting in a limited improvement only of the fixed costs per tA.
Table 1 – Effect of Economy of Scale on Opex – 1
Refinery Production Capacity, Mt/y* 1.4 3.2
Variable Costs, $/tA 85 83
Fixed Costs, $/tA 40 34
Total Operating Cost, $/tA 125 117 * Mt/y = million tonne alumina per annum
Table 2 provides an example in which the capacity increase involved an increase in equipment size rather than the number of operating units, illustrating in that case a more pronounced effect on fixed costs per tA.
Table 2 – Effect of Economy of Scale on Opex – 2
Refinery Production Capacity, Mt/y* 2.8 3.3
Variable Costs, $/tA 84 84
Fixed Costs, $/tA 50 42
Total Operating Cost, $/tA 134 126 * Mt/y = million tonne alumina per annum
3 Reference [3] provides an overview of Operating Cost
The conclusion from the above is that the primary effect of economy of scale on Operating Cost is on fixed costs (expressed per tA), and particularly if a capacity increase is the result of an increase in equipment size rather than equipment number.
3.2.2 Effect on Capital Cost4
Economy of scale has the following main effects5 on Capital Cost:
• In general larger size equipment, particularly tanks and vessels, is more cost effective per tonne alumina (tA) produced because larger tanks have a smaller surface area over volume ratio than smaller tanks, hence are cheaper in material cost per m3 stored volume. This effect is sometimes known as the “0.6 factor rule”6, and potentially represents a significant drop in capital cost per tA (note: this factor may be different for different equipment types and unit operations). Although technological improvements have resulted over time in a general increase in equipment size available for most processing equipment (vessels, tanks, pumps, mills, filters, etc), there are physical, technical and/or economic limitations to the size of all equipment. In addition, design considerations may favor in specific cases a large number of small equipment over a small number of large equipment.
• Infrastructure (both shared and non-shared) costs are diluted (e.g. piperacks, water supply, power distribution), and spare equipment may be shared in case of a larger production capacity resulting in the construction of more units. Both of these result in a lower capital cost per tA produced. As an illustration: for a refinery with two digestion trains, shared facilities represent indicatively 20-25% of its capital cost (includes raw materials handling, general facilities, shared spares, etc). Here too there are limitations: both with respect to sharing of spare equipment and because capacity increases in infrastructure are required at some stage.
The overall effect is a drop in capital cost per tA produced at higher production capacities. A straightforward power factor relationship between these would look like Figure 2.
Figure 2 – Refinery Capex vs Design Capacity – Power Factor
In many cases however plant (and thus project) capacity increases are a combination of increases in equipment size and in equipment numbers (e.g. as a result of an increase in operational
4 Reference [4] provides an overview of Capital Cost. 5 A second-order effect is an increased plant on-line time as a result of a plant consisting of more than one train resulting in a slightly lower capex per annual tA. 6 Theoretically the factor is 0.67.
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units / trains). In addition, an increased project scope also adds (at some stage disproportionally) to its complexity.
As a result, actual capital cost per tA produced may deviate from a smooth curve as shown in Figure 2. In fact Canbäck and others [5] refer to Bain who found in a study of twenty industries that at the plant level, beyond a minimum optimum scale few additional economies of scale can be exploited.
Available information suggests for the alumina industry that with respect to the relationship of refinery capital cost and design capacity, a differentiation can be made in two design capacity ranges as illustrated in Figure 3:
• Up to about 1.5 Mt/y: a power factor of ~0.7.
• Above about 1.5 Mt/y: a power factor of ~0.9.
Figure 3 – Refinery Capex vs Design Capacity
From Figure 3 it would appear that although further gains in capital cost per tA are possible at design capacities above ~1.5 Mt/y, these will be limited. A design capacity of about 1.5 Mt/y for an alumina refinery might perhaps be the “minimum optimum scale” referred to by Canbäck . Note that 1.5 Mt/y is meant to be indicative only.
This raises the question how this result can be reconciled with the design capacity of some future planned projects which are well above 1.5 Mt/y (refer Figure 1).
3.2.3 Infrastructure Costs & Overall Economics
The explanation for the above result is that greenfield projects have infrastructural requirements which may include access roads and bridges, a railway line, port facilities, and employee living facilities. In case of extensive infrastructural requirements, the related capital cost is significant and has a disproportional bearing on the economics of a smaller capacity greenfield project.
An example may illustrate the above for two greenfield project options at the same location: option 1 at 1.5 Mt/year alumina production design capacity, and option 2 at 3 Mt/year. Assumed infrastructural requirements for this location:
• 100 km railway line.
• Jetty and wharf, and ship loading/unloading facilities at the alumina export port.
• Employee housing and living facilities.
Table 3 provides indicative numbers for capital, operating and sustaining capital costs for the two options considered in this example and their economics.
Table 3 – Effect of Capacity on Overall Project Economics
Refinery Capacity 1.5 Mt/y 3 Mt/y
Capital Cost*, M$ Mine Refinery Infrastructure (railway, port, town) Total Capital Cost*, M$
$/AnntA
137 125
Economics# (indic.) NPV(8%), M$ IRR, % Payback period, y
- 139 7
369 9 9
* Basis W Europe, Mid 2010 US$ # Alumina price at 325 $/tA
Table 3 shows that, despite the Refinery capex per annual tA for the two options following the trend illustrated in Figure 3, the overall project economics flip from a significant negative NPV (with IRR 7% and payback period 10.5 years) to a significant positive NPV (with IRR 9% and payback period 8.5 years).
A major contributor is the disproportional increase in $/tA of the Infrastructure capex. To underpin that: had the delta in capital cost between the two project options expressed in $/Annual tA remained unchanged from the delta between the two refineries, the economics of the 1.5 Mt/year project (in that case at a total capex of 1,383 $/AnntA) would have looked as follows: NPV(8%) = -12 M$; IRR = 8%; Payback period = 9.5 years.
On re-considering the trend shown in Figure 1, the reasoning could be turned around: a disproportionate increase in project scale is required to result in acceptable economics.
In a similar context, A. Kjar in his paper presented at the TMS 2010 Annual Meeting [6] discusses in general terms the uncompetitive capital cost of recent Western-developed greenfield alumina projects as a result of (among other reasons) large project size and increased project complexity.
Consequences
The indicated increase in the design / initial capacity of greenfield (bauxite mine and) alumina refinery projects over the past decades has had the following major consequences:
• The complexity of these mega projects7 has increased significantly, especially in terms of project planning and management. Significant infrastructural works are often required, involving extensive government involvement, adding to project complexity.
• Project capital cost has grown to several billion USD, and project owners reduce risk through project financing and the formation of multi-party joint ventures. This is perfectly reasonable, however it complicates project implementation (e.g. with respect to decision making processes).
• Due to the financial commitments involved, globally only a limited number of (very) large companies have the financial and human resources to develop greenfield bauxite & alumina projects.
7 Typically projects over 1 billion US$.
7
• For the same reasons (project scope, complexity), only a limited number of engineering firms have the required engineering, construction and project management skills and experience to successfully implement these projects.
• Typically a project life of 30+ years is (implicitly) applied to justify the significant investment of a greenfield bauxite & alumina project. Reason: an alumina refinery can operate effectively for decades (refer e.g. Paranam, Gove, Kwinana, QAL). For greenfield bauxite & alumina projects with a captive refinery this means that the bauxite deposit on which a project is based should be able to sustain refining operations for such a period. Therefore only (very) large bauxite deposits are developed, indicatively 200-300 Mt and more.
In summary, worldwide only a small number of companies develop mostly very large greenfield bauxite and alumina projects, which often take a decade and more to develop.
Where from here?
With an objective to lower the threshold for the development of bauxite and alumina projects, the question may be asked if the underlying trend, viz. ever-increasing alumina refinery design capacities, is inevitable, or if viable alternatives exists. The basic reason for the trend being economics (refer section 3.2), the question could be reformulated as follows: is it possible to develop smaller greenfield bauxite and alumina projects at acceptable economics?
A. Kjar addresses this question and some of the issues discussed above, albeit from a different perspective, in his earlier mentioned paper. He indicates that as a means to overcome some of these issues, attempts were made by others: 1. To gain improved control over the project execution process; and 2. To increase the level of pre-assembly to reduce total costs of on-site construction labor and low productivity – refer also a paper by R. Valenti and P. Ho [7]. A. Kjar proposes the use of replication of a modern plant design, and small increments of capacity (without quantifying a capacity), in order to quickly and more cost-effectively build a large plant / project.
Although A. Kjar’s paper has a different angle (viz. building a large plant at lower capital cost), there are overlaps with the subject of the current paper (investigating the possibility to lower the threshold for the development of – smaller – bauxite and alumina projects).
To further explore the subject, a more in-depth look at the make- up of a greenfield project’s capital cost is required.
4. Capital Cost Make-up Refinery Capital Cost
4.1.1 Overview
The capital cost of a greenfield alumina refinery may be split up as shown in Table 4. In this table typical numbers are shown for a low-temperature digestion alumina refinery with a 1.5 Mt/y production capacity. Note that actual numbers may deviate significantly as a result of bauxite quality, technology choices, plant location, etc.
Table 4 – Greenfield 1.5 Mt/y Aa Refinery Capital Cost (typ.)
Cost Item 1.5 Mt/y
Direct Costs Equipment* Commodities#
Total Direct Costs, M$
78 256 180 190
Contingency, M$ 161
Total Refinery Capital Cost&, M$ 1,635 * Incl. steam & power generation, sub stations, residue disposal, water supply, communication & info systems # Incl. concrete, steel, mechanical bulks, piping, wire and cable, etc & Basis W Europe, Mid 2010 US$
4.1.2 Commodities and Plant Layout Aspects
Table 4 illustrates that the Commodities represent a very significant element in the refinery capital cost. Commodity amounts and their related capital costs reflect plant design including plant layout.
Current alumina refinery layouts are designed to accommodate additional (future) digestion units (and all of the other required process units – e.g. precipitation, evaporation). The consequence is that plant design is not optimized for its initial production capacity. Plant layout is characterized by an “open architecture”, at best compromising between on the one hand the limited layout requirements for the initial / design capacity and on the other hand the more extensive requirements to accommodate future additional process units. And in the worst case consisting of a layout of a large-capacity plant of which part is built, resulting in an inefficient plant layout for the design / initial capacity. In addition, in some cases plant design includes equipment which at some future stage might be used to its full capacity, but operates (well) below design for a considerable part of its lifetime.
4.1.3 Alternative Approach – Dedicated Plant Capacity
A. Kjar’s proposal to use replication means that a design is developed for a dedicated production capacity. Or putting it differently, this alternative design approach aims at designing an alumina refinery for a dedicated production capacity, i.e. without provisions for future expansions. This approach enables optimizing plant layout for the targeted production capacity, e.g. with respect to positioning similar equipment close to each other, use of common spares, etc.
This more “closed” layout architecture results in a more efficient plant layout, reflected for example in the design of main plant piperacks. This is illustrated in Figure 4 which shows the main piperack layout for a typical (current design) 1.5 Mt/year capacity refinery ( i.e. in the expectation that additional production lines in the various areas will be added in the future), and the layout for a dedicated 1.5 Mt/y capacity alumina refinery (same scale).
The alternative approach with its more closed layout design impacts positively on commodity volumes: for the same production capacity, commodity volumes for a greenfield plant designed along this alternative approach are similar to that of a brownfield expansion of an existing refinery. This is illustrated in Figure 5 which shows the total length of piping of greenfield and
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brownfield projects as function of plant production capacity, and the requirement of a dedicated plant of 1.5 Mt/y capacity.
This approach also stimulates focusing on a “lean” design and exploit any potential overdesign right from start-up (refer the comment made in section 3.1).
Figure 4 – Main Piperack Layout Comparison
Figure 5 – Total Piping as function of Plant Capacity
4.1.4 Effect Alternative Approach on Commodities Cost
A dedicated greenfield plant design results in lower amounts (in some cases significantly lower amounts) per annual tA produced of commodities such as steel, concrete and piping. This is
reflected in lower Commodities costs, resulting in lower Direct Capital Costs, in turn lowering Indirect Capital Costs. The overall effect on the capital cost of a greenfield dedicated low- temperature digestion alumina refinery of 1.5 Mt/y is illustrated in Table 5 (indicative numbers).
As can be seen in this table, the alternative approach improves the total refinery capital cost indicatively by over 10%. In fact the capital cost expressed per annual tonne of alumina capacity is lower than that of the current-design refinery at 3 Mt/y capacity (976 vs 1,000 $/Ann tA – refer Table 3).
Table 5 – Comparison of Refinery Capital Costs (indic.)
Cost Item 1.5 Mt/y Refinery Capacity
Current-design Dedicated
231 539
682
Indirect Costs Freight EPCM Temp. Constr., start-up, Comm. Owner’s Eng. & Other Costs Total Indirect Costs, M$
78 256 180 190
1,635 1,090
1,464 976
* The more efficient plant layout enables slightly lower equipment cost as a result of a more efficient use of common spare equipment # Basis W Europe, Mid 2010 US$
4.1.5 Compact Refinery – Simple & Limited Scope
Along the lines of A. Kjar’s paper (although he does not quantify “small increments of capacity”), applying the proposed dedicated- capacity approach to a compact alumina refinery capacity of 0.4 Mt/y results in a project with a simple and much more limited scope. Available data suggest that as a result some Indirect capital cost items decrease more than proportionately, particularly costs related to temporary construction and start-up support, camp and other construction related items, and owner’s costs.
Table 6 illustrates the capital cost for a 0.4 Mt/y alumina refinery based on a dedicated design (indicative numbers). The table shows that the capital cost per annual tonne alumina (1,295 $/AnntA) is higher than that of the much larger 1.5 Mt/y dedicated plant (976 $/AnntA – refer Table 5), however is at a level which could result in a project with acceptable economics, provided Infrastructure capital cost is limited (compare with the 1,293 $/AnntA for the overall project capital cost of a 3 Mt/y refinery – see Table 3). Table 6 also shows that the total capital cost is at a level which would enable many more (relatively small) companies to develop such a project without necessarily requiring the formation of multi-party joint ventures, simplifying overall project management and thus enabling to lower costs (effect not included in Table 6).
Note that the 0.4 Mt/y refinery production capacity used here is not fixed but is meant to typify a capacity range of 0.3-0.6 Mt/y. The higher end of this range is limited by the objective to end up with a total project capital cost well below 1 billion US$, the lower end is determined by logistical limitations (e.g. with respect to caustic soda and fuel oil shipments) and may vary for different locations.
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95 177
272
Indirect Costs Freight EPCM Temp. Constr., start-up, Comm. Owner’s Eng. & Other Costs Total Indirect Costs, M$
28 91 37 33
518 1,295
Infrastructure Capital Cost
As mentioned above, in order to realise acceptable economics for a project based on a compact dedicated production capacity, Infrastructure capital cost should be limited. Conversely a project based on a compact plant capacity has very limited infrastructural requirements and has several advantages over a large plant, particularly if the project is located close to an existing port, e.g. it may be allowed closer to residential areas (i.e. is closer to existing infrastructure); the existing infrastructure may be sufficient for a small plant, but not for a big plant; a suitable location for a small residue disposal area is easier to find than for a large one, etc. As outlined in section 5.3 several such locations exist worldwide.
Refinery Technologies
Note that the alternative approach proposed above is independent of the selected refinery technologies, while at the same time stimulating to focus on improvements, e.g. positioning similar equipment close to each other, the use of common spares, etc.
Replication and Indirect Costs
A. Kjar indicates in his paper that the use of replication of a modern design at small capacity increments has as one of its main advantages far lower indirect capital costs, comprising Project management; Procurement; and Technology & EPCM fees.
Although no direct quantification is mentioned in the paper, this appears consistent with the results discussed above for a dedicated plant design at a compact production capacity. Some of the replication-related cost savings mentioned by A. Kjar may come on top of the cost improvements indicated in this paper.
5. New Bauxite Deposit Development Model
New Development Model
The bauxite deposit development model proposed in this paper as detailed above is based on the development of a dedicated compact alumina refinery in the range 0.3-0.6 Mt/year.
The dedicated refinery design has no provisions for future expansions, enabling optimizing plant layout and resulting in lower capital cost per tonne of alumina (tA) produced compared with current plant design. The compact capacity results in a
project with a simple and limited scope, further improving capital cost per tA produced.
To ensure acceptable economics, Infrastructure capital cost should be limited. At the same time such a project has few infrastructural requirements , especially if located close to an existing port.
Main Advantages
The main advantages of the new development model are:
• Due to the significantly smaller project capital expenditure involved (lower risk), this approach enables the development of bauxite & alumina projects by smaller companies without a need to form multi-party joint ventures, i.e. it increases the number of companies potentially interested in developing bauxite deposits. In other words competition increases, which should result in more efficient use of resources, both in terms of capital resources and in terms of global bauxite deposits.
• Due to the decreased complexity of compact alumina refining projects, the number of engineering companies potentially able to develop these projects increases, again resulting in more competition and the potential for a more efficient use of resources.
• Small and simple projects carry less risks and require less time to develop, implement and start-up, all of which has a positive impact on economics.
• A long term alumina refining project based on the new model requires only a relatively small bauxite deposit (a deposit of 40 Mt could support a 0.4 Mt/y project for 30 years). This means that worldwide the number of bauxite deposits that lend themselves to development increases.
• The new development model may be applied also to the development of part(s) of a large deposit.
• This approach may in some cases lower the threshold to increase value creation through alumina refining rather than being limited to bauxite export sales. This is attractive both to host countries and to companies developing potential bauxite & alumina projects.
• In some cases, an adapted version of this new development model may enable bauxite deposit development even in locations with little existing infrastructure, albeit at a larger than compact scale (refer e.g. to Table 5 for a dedicated 1.5 Mt/year capacity project).
Possible Locations
Following are some examples of bauxite deposits that may lend themselves to development via the proposed alternative approach (between brackets the potential alumina export port):
• Haden, Queensland, Australia (Brisbane).
• Bindoon, Western Australia (Fremantle).
• Trelawny, Jamaica (Discovery Bay).
• Kibi, Ghana (Tema).
The above list is not exhaustive and meant to be illustrative only.
In addition some bauxite deposits which in view of their size could support the current development approach with large- capacity alumina refining projects, may also lend themselves to stage-wise development through the proposed alternative
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approach. In this case these deposits would be able to support several (smaller) greenfield bauxite and alumina projects as outlined in the last bullet point of section 5.2 above. Example: some of the Eastern Ghats deposits in Orissa and Andhra Pradesh, India, e.g. the Kutrumali deposit (with Visakhapatnam as potential alumina export port).
6. References 1. R. den Hond, “Technology Choices for Greenfield Alumina Plants” (paper presented at ICSOBA 2008, Bhubaneswar), pp 267-270.
2. P.J.C. ter Weer, “Greenfield Dilemma – Innovation Challenges” (paper presented at Light Metals 2005, San Francisco, California), pp 17-22.
3. P.J.C. ter Weer, “Operating Cost – Issues and Opportunities” (paper presented at Light Metals 2006, San Antonio, Texas), pp 109-114.
4. P.J.C. ter Weer, “Capital Cost: To Be or Not To Be” (paper presented at Light Metals 2007, Orlando, Florida), pp 43-48.
5. S. Canbäck, P. Samouel, and D. Price, “Do Diseconomies of Scale Impact Firm Size and Performance – A Theoretical and Empirical Overview”, Journal of Managerial Economics, 2006, Vol. 4, No. 1, pp 27-70.
6. Anthony Kjar, “A Case for Replication of Alumina Plants” (paper presented at Light Metals 2010, Seattle, Washington), pp 183-190.
7. R. Valenti and P. Ho, “Rio Tinto Alcan Gove G3 Experience on Pre-Assembled Modules” (paper presented at the Alumina Quality Workshop 2008, Darwin), pp 1-5.
For further information, please contact P.J.C. ter Weer at [email protected] or visit www.twsservices.eu.
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STUDY ON THE CHARACTERIZATION OF MARGINAL BAUXITE FROM PARÁ/BRAZIL
Fernanda A.N.G. Silva1,2, João A. Sampaio2, Francisco M. S. Garrido1, Marta. E. Medeiros1
1Universidade Federal do Rio de Janeiro, Instituto de Química, Avenida Athos da Silveira Ramos, 149, Cidade Universitária; Rio de Janeiro, RJ, 21941-909, Brasil.
2Centro de Tecnologia Mineral / CETEM-MCT, Avenida Pedro Calmon, 900, Cidade Universitária; Rio de Janeiro, RJ, 21941-908, Brasil.
Keywords: Marginal Bauxite, Mineralogical and Chemical Characterization
Abstract Bauxite from Pará is divided into five different layers. However, only one is processed. The crystallized-amorphous (CAB) phase is considered a marginal bauxite because it presents a high quantity of SiO2reactive and its use depends on special technologies. CAB was characterized and the results were compared with the bauxite used nowadays in the alumina plant. Characterization was performed by XRD, IR, XRF, chemical analysis, TGA and SEM. XRD determined the mineral content: such bauxite is gibbsitic and has been associated with kaolinite and hematite. IR data supported the XRD results. XRF was used to determined the sample's chemical composition. The chemical content of Al2O3available and SiO2reactive was determined by potentiometric titration and FAAS. The results found for the Bayer process sample were 41.7% and 7.1%, respectively. TGA observed the bauxite decomposition and SEM supplied chemical and thermal analysis. Thus, based on stoichiometric relations of the bauxite components decomposition, it was possible t

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