5th International Symposium on

High-Temperature Metallurgical Processing

New proceedings volumes from the TMS2014 Annual Meeting, available from publisher John Wiley & Sons:

www.wiley.com

www.tms.org

Proceedings of a symposium sponsored by

The Minerals, Metals & Materials Society (TMS)

held during

February 16-20, 2014San Diego Convention Center

San Diego, California, USA

Edited by:

Tao Jiang, Jiann-Yang Hwang,

Mark E. Schlesinger, Onuralp Yucel, Rafael Padilla,

Phillip J. Mackey, and Guifeng Zhou

5th International Symposium on

High-Temperature Metallurgical Processing

Copyright © 2014 by The Minerals, Metals & Materials Society. All rights reserved.

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TABLE OF CONTENTS5th International Symposium on High-Temperature Metallurgical Processing

Preface .............................................................................................................. xiii About the Editors................................................................................................ xv

High Efficiency New Metallurgical Technology

Development of Process Flow Sheet for Looping Sulfide OxidationTM ofMolybdenite Concentrates .................................................................................... 3 J. Lessard, L. Shekhter, D. Gribbin, and L. McHugh

Slag Structures and Properties by Spectroscopic Analysis: Effect of WaterVapor Relevant to a Novel Flash Ironmaking Technology................................. 11 M. Mohassab-Ahmed and H. Sohn

An Innovative Electro-Winning Process for Titanium Production .....................19 G. Granata, Y. Kobayashi, R. Sumiuchi, and A. Fuwa

A New Bottom Gas Purging System for Stationary and Tilting Copper Anode Furnaces ..................................................................................................25 G. Vukovic and K. Gamweger

A Pilot-Plant Scale Test of Coal-Based Rotary Kiln Direct Reduction of Laterite Ore for Fe-Ni Production ..................................................................33 G. Li, J. Liu, M. Rao, J. Luo, C. Wang, and Y. Zhang

Preparation of Ferronickel Alloy Nugget through Reduction Roasting of Nickel Laterite Ore .........................................................................................41 P. Chen, X. Lv, E. Guo, Q. Yuan, and M. Liu

Preparation of High Melting Point Alloys and Refractory Compounds with Its Own Chemical Energy...........................................................................51 Z. Dou, G. Shi, T. Zhang, Y. Guan, M. Wen, X. Jiang, and L. Niu

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Reductive Sulfur-Fixation Smelting of Stibnite Concentrate in Sodium Molten Salt .........................................................................................................59 H. Xue, Y. Chen, S. Yang, C. Tang, and M. Tang

Separation of Perovskite Phase from CaO-TiO2-SiO2-Al2O3-MgO System by Supergravity...................................................................................................67 J. Gao, J. Li, and Z. Guo

New Process for Producing High Grade Iron Concentrate by Roasting Siderite Ore with Microwave Energy ................................................................. 73 S. Ju, L. Zhang, J. Peng, S. Guo, X. Wang, and Y. Wang

Fundamental Research of Metallurgical Process

Effect of Water Vapor on the Activities of FeO and MgO in Slags Relevant to a Novel Flash Ironmaking Technology...........................................................83 M. Mohassab-Ahmed and H. Sohn

Activities of NbOX in Some CaO-Al2O3-SiO2-“Nb2O5” Melts at 1873K ..........91 B. Yan, Y. Wang, and J. Fan

Reaction Behaviour of Sulfides Associated with Stibnite in Low TemperatureMolten Salt Smelting Process without Reductant...............................................99 L. Ye, C. Tang, Y. Chen, M. Tang, and W. Zhang

Reduction Product Separation by Vacuum Distillation in the Process ofTitanium Sponge Preparation ...........................................................................107 L. Li, K. Li, X. Chen, Y. Yang, C. Sun, and Q. Miao

The Interface Reaction and Transport of Oxygen between the Molten Melt and CaO-MgO-Al2O3 Slag................................................................................115 T. Zeng, J. Xu, J. Li, J. Zhang, and Y. Guo

High-Temperature Creep Deformation and Change in Porous Structure ofGraphite Cathode in Aluminum Electrolysis Process.......................................123 T. Chen, J. Xue, and X. Li

The Dissolution Rate of Solid Alumina Inclusion into Molten CaF2-CaO-MgO-Al2O3-SiO2 Slags...................................................................131 G. Shi, T. Zhang, L. Niu, and Z. Dou

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Alloy and Materials Preparation

A Refinement Study of SHS Alloys by Mini Vacuum Arc Melting System ....139 M. Alkan, S. Sonmez, B. Derin, and O. Yücel

An Investigation on the Self-Propagating High Temperature Synthesis of TiB2 ..............................................................................................................147 O. Yücel, M. Bugdayci, and A. Turan

Characteristics of Solidification Structure of Wide-Thick Slab of Steel Q345 ....................................................................................................153 S. Luo, M. Zhu, W. Wang, S. Zheng, and F. Xu

Determination of Surface Tension for FeCrMnNi Alloy with Varying Sulfur and Phosphorous Relevant to Gas Atomization................................................161 T. Dubberstein and H. Heller

Electrolysis Contribution to the Yield of Alloy Elements and the ExchangeCurrent Density of Manganese and Chromium during DC-Arc SteelMelting/Refining Process .................................................................................169 J. Chen and M. Jiang

Experimental Study of the Thermodynamics of the Fe-Nb-C Melts ................177 B. Yan, D. Guo, L. Zhang, and J. Zhang

Preparation of Nitrogenous Ferrovanadium by Gaseous Nitriding in the Liquid Phase Ferrovanadium ..................................................................185 W. Liu, K. Dong, and R. Zhu

Study on Key Technologies of 38CrMoAl Steel Produced by BOF-LF-RH-CC Process..................................................................................193 Y. Chen, M. Zhang, J. Zeng, and H. Pan

The Evolution and Morphology of Sulfide Inclusions in 95CrMo Hollow Steel .....................................................................................................201 J. Chen, S. Zhang, C. Cai, Y. Liu, H. Li, and J. Yang

Electrochemically Preparing of Ni-Fe Alloys in Molten Sodium Hydroxide...209 J. Ge, J. Xiao, S. Jiao, and H. Zhu

Roasting, Reduction and Smelting

Commissioning of a Second Cobalt Recovery Furnace at Nchanga Smelter ...217 M. Masanza, R. Cheeba, and K. Ng'andwe

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Analysis of the Attaching Slag to the Lining for Pillar and Walking Beam in the Hot Rolling's Heating Furnaces ..............................................................225 G. Xu and Y. Wang

A Study of Benefiation of Siderite by Direct Reduction-MagneticSeparation Process ............................................................................................231 D. Zhu, Y. Luo, and J. Pan

Development and Industrial Application of an Improved Lead Oxygen-Enriched Flash Smelting Process........................................................239 C. Wang, W. Gao, W. Yang, F. Yin, and B. Ma

Effects of Reducer and Slag Concentrations in the Iron-Carbon NuggetsCoalescence in Self Reducing Processes ..........................................................247 A. Nogueira, C.Takano, M. Mourão, and A. Pillihuaman

Excavation of a 48 MVA Silicomanganese Submerged-arc SiMn Furnace inSouth Africa - Part I: Methodology and Observations......................................255 J. Gous, J. Zietsman, J. Steenkamp, and J. Sutherland

Industrial Experimental Study on Dephosphorization Pretreatment in Combined-Blowing Converter Process.........................................................271 Z. Yan, X. Xing, J. Zhang, C. Zhao, P. Pei, and J. Rao

Roasting Characteristics of Oxidized Pellets of Vanadium-Titanium Magnetite Concentrates ....................................................................................279 X. Chen, Y. Huang, M. Gan, X. Fan, L. Yuan, and W. Lv

Thermodynamic Computation and Analysis for the Carbothermic Reduction of TiO2 ..............................................................................................................287 L. Wen, J. Tu, L. Wang, G. Qiu, and C. Bai

Kinetic Analysis of Smelting Reduction of V2O3 in Blast Furnace Slag by Dissolved Carbon in Liquid Iron .................................................................295 X. Zeng, Y. Wang, H. Li, B. Xie, and J. Diao

The Distribution of Boron between CaO-SiO2-MgO-Al2O3-TiO2and Liquid Fe by Chemical Equilibrium Technique.........................................303 S. Ren, J. Zhang, X. Xing, and Z. Liu

Study on Limonite Powder by Flash-Magnetic Roasting .................................311 J. Li, Y. Yu, W. Chen, and X. Liu

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Study on the Reduction Mechanism of Panzhihua (China) Ilmenite Activated by Ball Milling .................................................................................319 Y. Lei, Y. Li, W. Hou, J. Peng, L. Xu, and X. Xu

Sintering of Ores and Powder

Microscopic Mechanisms of Spark Plasma Sintering in a TiAl Alloy .............329 Z. Trzaska, A. Couret, and J. Monchoux

Effects of Fuel's Distribution on NOX Emission in Iron Ore Sintering.............337 X. Fan, W. Lv, M. Gan, X. Chen, Z. Yu, Y. Zhou, J. Wang, and Q. Chen

Study on the Metallurgical Performances of Typical Manganese Ores ............345 Y. Zhang, Y. Zhang, Z. You, Y. Zhao, G. Li, and T. Jiang

Comprehensive Emission Reduction of Sintering Exhaust Gas Pollutant with Addition of Urea.......................................................................................353 H. Long, J. Xiao, P. Wang, X. Xia, and A. Wang

Fabrication of Al-Si Alloys by Microwave Sintering .......................................361 L. Xu, M. Yan, Y. Xia, J. Peng, W. Li, L. Zhang, C. Liu, and Y. Li

Influence of Limestone Types on Iron Ore Sintering .......................................369 X. Chen, Q. Chen, M. Gan, X. Fan, Z. Yu, Z. Ji, J. Wang, and Y. Zhou

Effect of Aluminum Oxide on Compressive Strength of Pellets and ItsMechanical Analysis.........................................................................................377 J. Zhang, Z. Wang, X. Xing, and Z. Liu

Process Optimization of Removing Chlorine of Zinc Dross Using Microwave Roasting.........................................................................................385 S. Lu

Physico-Chemical Properties and Sintering Performance of Canadian IronConcentrate.......................................................................................................393 J. Pan, B. Shi, D. Zhu, and X. Li

Study on Pre-Granulation Technology for Strengthening Sintering of HighProportion Iron Ore Concentrate ......................................................................401 X. Chen, J. Wang, X. Fan, M. Gan, Y. Zhou, W. Lv, Q. Chen, and Z. Yu

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Influence of B2O3 on Phases and Metallurgical Properties of High Ti-BearingVanadium-Titanomagnetite Sinter....................................................................409 L. Sun, S. Ren, X. Xing, and F. Wang

Simulation and Modeling

Impact of Concentrate Feed Temporal Fluctuations on a Copper Flash Smelting Process...............................................................................................419 A. Lamoureux, A. Blackmore, and M. Jastrzebski

Influence of Microwave Radiation on Phosphorus Removal Process of Oolitic High-Phosphorus Iron Ore Fines......................................................427 H. Tang, W. Liu, L. Ma, and Z. Guo

Modeling and CFD Simulations of Multiphase Melt Flows in SteelmakingConverters under Combined Blow Conditions .................................................435 V. Seshadri, E. Rodrigues, C. da Silva, I. da Silva, B. Lima, C. Mattioli, and M. Prado

Mathematical Modeling for Developing Iron Bath Reactor with H2-CMixture Reduction ............................................................................................443 B. Zhang, H. Zhang, J. Liu, L. Liang, D. Wang, Y. Yang, H. Guo, and X. Hong

Numerical Simulation Study on Immersed Side-Blowing in C-H2 SmeltingReduction Furnace ............................................................................................451 K. Feng, J. Zhang, B. Wang, J. Xu, J. Xie, W. Cheng, D. Yin, and S. Zheng

Study of Mixing Phenomena during RH Refining Using Water Modeling ......459 F. Li, L. Zhang, Y. Liu, and Y. Li

Modeling and CFD Simulations of Multiphase Melt Flows in SteelmakingConverters during Top Blow ............................................................................467 V. Seshadri, E. Rodrigues, C. da Silva, I. da Silva, B. Lima, C. Mattioli, and M. Prado

Optimization System of Iron Ores Proportion for Sintering Process................475 X. Fan, X. Huang, X. Chen, and M. Gan

Simulation on Calciothermic Reduction Process of Titanium Dioxide ............483 B. Xu, J. Zhao, B. Yang, X. Chen, D. Wang, and L. Kong

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Numerical Simulation on Temperature Distribution and Microstructure Growth of Horizontal Unidirectional Solidification Equipment.......................491 L. Bai, H. Zhong, B. Wang, Q. Zhai, and J. Zhang

Treatment of Solid Slag/Wastes and Complex Ores

A Comparative Study on the Reduction of Mill Scale from Continuous Casting Processes..............................................................................................499 M. Bu�dayc�, A. Turan, M. Alkan, F. Demirci, and O. Yücel

A Pilot-Plant Scale Test on DRI Preparation from High-Alumina Limonite Ore by Coal-Based Rotary Kiln Direct Reduction Process...............................507 G. Li, C. Wang, M. Rao, Y. Zhang, and T. Jiang

The Effect of Various Ration of Citric and Sulfuric Acid on the Structure and Leaching Properties of Pellets of Laterite Roasted at High Temperature ..515 Y. Chen and H. Li

Improving the Beneficiation of Low-Grade Saprolitic Nickel Laterite byReduction Roasting in the Presence of Additives .............................................523 D. Zhu, G. Zheng, J. Pan, Q. Li, Y. An, and J. Zhu

Preparation of Synthetic Rutile from Titanium Slag.........................................531 Y. Guo, J. He, T. Jiang, S. Liu, F. Zheng, and S. Wang

Characterization of Magnetic Roasting and Magnetic Separation of a High-Alumina-Content Limonite Ore........................................................539 T. Jiang, X. Zhang, M. Rao, J. Zeng, Y. Zhang, and G. Li

The Research of Metallurgical Reaction Engineering in Oxygen BottomBlowing Copper Smelting Process ...................................................................547 Z. Cui, H. Yan, D. Shen, Z. Cui, and P. Yu

The Study of Recycling Ni/Fe from Laterite by Coal Pre-Reduction and Magnetic Separation ..................................................................................555 Y. Chen, H. Li, and P. Zhang

The Phase Transformation of Laterite Ore Treated with Insufficient Reductant ..........................................................................................................563 Y. Wang, Y. Guo, T. Zeng, J. Zhang, B. Bai, and G. Gao

Adsorptive Removal of Phosphate Anions from Municipal Wastewater UsingRaw and Wasted Low Grade Phosphorus-Containing Iron Ore Adsorbent......571 X. Yuan, W. Xia, J. An, and W. Yang

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Microwave Heating, Energy and Environment

Research on Microwave Roasting of High Titanium Slag Process ..................581 K. Yang, J. Peng, L. Zhang, H. Zhu, G. Chen, X. Zheng, X. Tan, and S. Zhang

Calculation and Analysis the Influence on the Cooling Water Velocity and Hot Metal Circulation to the Long Life BF................................................589 K. Jiao, J. Zhang, H. Zuo, R. Xu, and J. Hong

Investigation of Mixing Phenomenon Using Water Model of C-H2 SmeltingReduction Furnace ............................................................................................597 J. Xie, K. Feng, J. Xu, and J. Zhang

Numerical Simulation of Microwave Absorption of Regenerative HeatExchangers Subjected to Microwave Heating ..................................................605 X. Shang, J. Chen, W. Zhang, J. Shi, G. Chen, and J. Peng

Effects of Microwave Heating on Reduction of Ilmenite and Its Separation....613 Z. Huang, T. Li, L. Yi, and Y. Zhang

Study on the Dielectric Properties of Panzhihua Ilmenite Concentrates by Using Terminal Open Coaxial Reflection Method ......................................621 Y. Li, Y. Lei, W. Hou, X. Xu, J. Peng, and L. Xu

Optimization of Processing Parameters Using Response Surface Methodology for Microwave Direct Reduction of Titanic Iron Ore.................629 J. Jia, H. Zhu, J. Peng, L. Zhang, K. Yang, and G. Chen

Optimization on Drying of Ilmenite by Microwave Heating Using ResponseSurface Methodology........................................................................................637 Y. Zuo, B. Liu, L. Zhang, J. Peng, A. Ma, and B. Wang

Author Index..................................................................................................... 645 Subject Index .................................................................................................... 649

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PREFACE

This book collects selected papers presented at the 5th International Symposium on

High-Temperature Metallurgical Processing organized in conjunction with the 2014

TMS Annual Meeting in San Diego, California, USA.

As the title of symposium suggests, the book focuses on thermal processing of minerals,

metals, and materials and intends to promote physical and chemical transformations

in the materials to enable recovery of valuable metals or to produce products such as

pure metals, intermediate compounds, alloys, or ceramics through various treatments.

The symposium was open to participants from both industry and academia and focused

on innovative high-temperature technologies, including those based on non-traditional

heating methods as well as their environmental aspects. Because high-temperature

processes require high energy input to sustain the temperature at which the processes

take place, the symposium intends to address the needs for sustainable technologies

with reduced energy consumption and reduced emission of pollutants. The symposium

also welcomed contributions on thermodynamics and kinetics of chemical reactions

and phase transformations that take place at elevated temperatures.

More than 330 authors have contributed to the symposium through a total of 120

presentations. After reviewing the submitted manuscripts, papers were accepted for

publication in this book. The book is divided into eight sections:

1. High Efficiency New Metallurgical Technology

2. Fundamental Research of Metallurgical Process

3. Alloy and Materials Preparation

4. Roasting, Reduction and Smelting

5. Sintering of Ores and Powder

6. Simulation and Modeling

7. Treatment of Solid Slag/Wastes and Complex Ores

8. Microwave Heating, Energy and Environment

This is the fourth book exclusively dedicated to this important and burgeoning

topic published in the 21st century. We hope this book will serve as a reference for

both new and current metallurgists, particularly those who are actively engaged in

exploring innovative technologies and routes that lead to more energy efficient and

environmentally sustainable solutions.

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Before closing, we would like to thank all the authors of submitted papers, the reviewers,

and the publisher. There could not be this book without their contributions, time, and

efforts. We also want to thank Dr. Mingjun Rao and Mr. Jean Paul Dukuzumuremyi for

their assistance in collating and reviewing the submissions.

Tao JiangJiann-Yang HwangMark E. SchlesingerOnuralp YücelRafael PadillaPhillip J. MackeyGuifeng Zhou

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EDITORS

Tao Jiang received his M.S. in 1986 and Ph.D. in 1990, both from Central South University of Technology, Changsha, China. Then he joined the university and served as an assis-tant professor (1990–1992) and full professor (1992–2000). From 2000 to 2003, he was a visiting scientist to the De-partment of Metallurgical Engineering at the the University of Utah. Since 2003, Dr. Jiang has been a professor in the School of Minerals Processing & Bioengineering at Central South University. He was elected as Specially Appointed Professor of Chang Jiang Scholar Program of China in 2008 and has been the dean of the school since 2010.

Dr. Jiang’s research interests include agglomeration and direct reduction of iron ores and extraction of refractory gold ores. He has accomplished more than 50 projects from the government and industry, including National Science Fund for Distinguished Young Scholars program. He and co-worker invented the direct reduction process of composite binder pellets and three plants were set up based on the invention in China. He proposed the innovative composite agglomeration process of iron ore fines, which was put into production in 2008 in Baotou Steel Company, China. His investigation on the gold extraction of thiosulfate has moved this process forward. He is actively involved in the areas of utilization of non-traditional ferrous resources such as complex ores and various solid wastes.

Dr. Jiang has published 320 technical papers and six books, including Direct Reduction of Composite Binder Pellets and Use of DRI, Principle and Technology of Agglomera-tion of Iron Ores, Chemistry of Extractive Metallurgy of Gold, and Electrochemistry and Technology of Catalytical Leaching of Gold. He holds 32 patents and has more than 30 conference presentations.

Currently, Dr. Jiang serves as chair of the TMS Pyrometallurgy Committee, and as a member of the Ironmaking Committee of the Chinese Society for Metals.

Jiann-Yang (Jim) Hwang is a professor in the Department of Materials Science and Engineering at Michigan Techno-logical University. He is also the chief energy and environ-ment advisor of the Wuhan Iron and Steel Group Company. He has been the editor-in-chief of the Journal of Minerals and Materials Characterization and Engineering since 2002. Several universities have honored him as a guest professor, including the Central South University, University of Sci-ence and Technology Beijing, Chongqing University, and Kunming University of Science and Technology.

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Dr. Hwang received his B.S. degree from National Cheng Kung University 1974 and his M.S. in 1980 and Ph.D. in 1982, both from Purdue University. He joined Michigan Technological University in 1984 and has served as director of the Institute of Ma-terials Processing from 1992 to 2011. He has been a TMS member since 1985. His research interests include the characterization and processing of materials and their applications. He has been actively involved in the areas of separation technologies, pyrometallurgy, microwaves, hydrogen storages, ceramics, recycling, water treatment, environmental protection, biomaterials, and energy and fuels. He has more than 20 pat-ents and has published more than 200 papers and founded several companies. He has chaired the Materials Characterization Committee and the Pyrometallurgy Committee in TMS and has organized several symposia.

Mark E. Schlesinger is a professor of Metallurgical Engi-neering at the Missouri University of Science and Technol-ogy, where he has been since 1990. His research interests in-clude high-temperature thermochemistry, metals extraction and production, and phase equilibria of molten materials. He is a former Fulbright Scholar and Leif Ericsson Fellow. He is the co-author of Extractive Metallurgy of Copper (4th and 5th ed.), and the author of Aluminum Recycling (1st and 2nd ed.).

Onuralp Yücel completed his technical education with a Ph.D. in metallurgical engineering from Istanbul Technical University (ITU) where he has been a professor since 2002. He was a visiting scientist at Berlin Technical University between 1987 and 1988. He carried out his post-doctoral studies at New Mexico Institute of Mining and Technol-ogy, Socorro, USA between 1993 and 1994. Dr. Yücel has as many as 200 publications/presentations to his credit on topics including technological developments in the produc-tion of wide range of metals, ferroalloys, advanced ceramic powders and application of carbothermic and metalothermic processes among others. He was the vice chairman of the

ITU Metallurgical and Materials Engineering Department between 2004 and 2007. He was a director of the ITU Applied Research Center of Material Science & Production Technologies between 2006 and 2012.

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Rafael Padilla received his Ph.D. and M.S. degrees in metal-lurgy from the University of Utah in 1984 and 1977, respec-tively, and earned the title of Metallurgical Engineer from the Technical University of Oruro, Bolivia in 1975. Dr. Padilla joined the Department of Metallurgical Engineering, Univer-sity of Concepcion, Chile in 1986, and currently holds the rank of professor at that department. He is very much in-terested in research involving thermodynamics and kinetics of metallurgical reactions in both pyrometallurgy and hydro-metallurgy, volatilization of noxious minor elements in cop-per metallurgy, mathematical modeling of solvent extraction,

atmospheric leaching, and pressure leaching of refractory copper and arsenic sulfides. His present research interests continue on the vaporization of arsenic, antimony and bismuth from copper sulfides at roasting and smelting temperatures, and on the de-velopment of new processing methods for primary sulfides including chalcopyrite, enargite, and molybdenite.

Phillip J. Mackey is a consulting metallurgical engineer and specialist in non-ferrous metals with more than 40 years of international experience in all aspects of the non-ferrous and ferrous metals business. He is originally from Austra-lia where he received his Ph.D in metallurgical engineering from the University of New South Wales. Dr. Mackey played a leading role in the development of the Noranda Process, the world’s first commercial continuous copper smelting and converting process and one of the important copper technolo-gies developed in the 20th century. Dr. Mackey was a key developer of the Noranda Continuous Converter. He was also involved in a number of nickel sulphide and nickel laterite

projects around the world. He has authored or co-authored over 100 publications cov-ering many aspects of non-ferrous metallurgy. Active in the copper world, he is one of the co-founders of the Copper/Cobre series of international conferences, which began in 1987. Dr. Mackey worked for many years with Xstrata (formerly Falconbridge/Noranda) before retiring at the end of 2009 to start his own consulting company. He presently acts in a consulting role for a number of Canadian and international mining and metallurgical companies. He is a Past-President of the Metallurgy and Materials Society of the Canadian Institute of Mining, Metallurgy and Petroleum (1984–1985) and a fellow of both CIM and TMS. A recipient of several professional awards in Canada and the United States, he was awarded the Selwyn G. Blaylock Medal of the CIM in 2010 and received the Airey Award by The Metallurgy and Materials Society of CIM in 2012.

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Guifeng Zhou received his B.S. in materials science and engineering from the Northwest Industry University (China) in 1984, his M.S. in materials and heat treatment from the Huazhong University of Science and Technology in 1990, and his Ph.D. in materials physics and chemistry from the University of Science and Technology Beijing in 2000. For a year and a half as a senior visiting scholar, he researched microalloying technology at the University of Pittsburgh.Dr. Zhou is vice director of R&D center of Wuhan Iron & Steel (Group) Corporation and is also a professor and super-visor of Ph.D. students at Wuhan University of Science and

Technology. His work has concentrated on new steel product development, microstruc-ture, and mechanical properties of materials. Dr. Zhou has published more than 20 technical papers, holds four patents, won the Progress Prize in Science and Technology by Nation three times, is an expert with State Department special allowance, and is a member of the following groups: the editorial board of Research on Iron and Steel, the Chinese Metals Society, the Quality Control Society of China, and the Science and Technology Association.

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5th International Symposium on

High-Temperature Metallurgical Processing

DEVELOPMENT OF PROCESS FLOW SHEET FOR LOOPING SULFIDE OXIDATION™ OF MOLYBDENITE CONCENTRATES

Joseph D. Lessard1, Leonid N. Shekhter1, Daniel G. Gribbin1, Larry F. McHugh1

1Orchard Material Technology, LLC790 Turnpike Street, Suite 202

North Andover, MA 01845

Keywords: Looping Sulfide Oxidation, Molybdenite, Molybdenum Dioxide

Abstract

A process simulation of the conversion of molybdenum disulfide concentrates into molybdenum dioxide via the Looping Sulfide Oxidation process has been performed using HSC 7.1thermodynamic software. By decoupling molybdenite conversion and molybdenum oxidation, Looping Sulfide Oxidation changes the paradigm by turning molybdenite processing into an energy generator while producing a molybdenum dioxide, which has a lower vapor pressure and lower oxygen content than molybdenum trioxide. The Looping Sulfide Oxidation process selectively produces molybdenum dioxide over molybdenum trioxide. This process uses a stoichiometric mixture of oxygen and molybdenum trioxide as oxidants in the conversion of the molybdenum sulfide to the molybdenum oxide. The model simulates the two reactor scheme required by Looping Sulfide Oxidation and incorporates thermodynamic equilibrium simulations performed in FactSage 6.3.1 thermodynamic software. Energy capture is also maximized with heat exchanger systems to transfer heat released in reactions to preheat air.

Introduction

Conventional processing of molybdenum disulfide (molybdenite, MoS2) is performed in multiple hearth roasters in which a flotation concentrate containing 50-60% molybdenum is converted to molybdenum trioxide (MoO3). Molybdenum trioxide is often the final product sold to steel manufacturers who incorporate the high value metal into steel melts to improve the strength and high temperature performance of the steel. While the MoS2 traverses the hearths, the sulfur component is converted to gaseous SO2 while the molybdenum is oxidized in an excess of air. The temperature at each hearth is controlled by a combination of fossil fuel burners, air inlet ports, and in some cases, water spray jets, to obtain the appropriate temperature and reaction profiles such that the final MoO3 product is sufficiently pure with residual sulfur within the specification.

Due to the vast excesses of reaction air used, poor heat transfer and heat capture, and limited gas-solid reaction interface, the production of MoO3 in multiple hearth roasters is an inherently inefficient process. The excess reaction air used during roasting dilutes the SO2 in the off gas, which in turn forces the overdesign of downstream processing equipment. The large volumes of reaction air used and the convective loss of energy released during the oxidation of MoS2through the roaster walls and into the process off gas contribute to a very poor energy economy. Because the reaction that takes place must occur between the solid MoS2 phase and the gaseous O2, mass transfer is critical and as such the surface area available to the reactants is maximized in a multiple hearth roaster by slowly raking the powder MoS2 over the surface of the hearths. However, this process is time consuming and intimate contact of the solid phase with the gaseous

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5th International Symposium on High-Temperature Metallurgical ProcessingEdited by: Tao Jiang, Jiann-Yang Hwang, Mark E. Schlesinger, Onuralp Yucel, Rafael Padilla, Phillip J. Mackey, and Guifeng Zhou

TMS (The Minerals, Metals & Materials Society), 2014

one is difficult to achieve. In fact, it has been estimated that a majority of the reaction actually takes place while the material falls from upper hearths to lower hearths and is more exposed to the atmosphere [1].

Opportunities for improvement, therefore, exist in improving the energy economy of the MoS2conversion process, limiting the dilution of the SO2 in the off gas, and minimizing mass transfer limitations during conversion. Additionally, while it is the widely accepted product used by steel manufacturers, MoO3 itself can present processing concerns. Molybdenum trioxide has a high vapor pressure at a relatively low temperature that causes it to sublime at low temperatures leading to material losses [2]. Furthermore, the presence of three moles of oxygen per mole of molybdenum requires three equivalents of reducing agent during incorporation into steel. An attractive alternative for the steel industry, therefore, is molybdenum dioxide (MoO2), which does not have a high vapor pressure as compared the MoO3 and requires 33% less reducing agent to incorporate it into a steel melt.

Looping Sulfide Oxidation (LSO) has been proposed as a novel processing route to produce MoO2 in a manner competitive with conventional multiple hearth roasting technology. Previous work by the authors has outlined the thermodynamic and processing considerations to implement LSO to convert MoS2 concentrates to MoO2 selectively [3-5]. It is the purpose of this paper to outline a process flow sheet and discuss some of the processing considerations needed to realize the potential of LSO technology.

Background

Figure 1. General flow sheet for the Looping Sulfide Oxidation process.

Sulfide Oxidation Process Thermochemistry

LSO conversion of MoS2 to MoO2 is a two-step process (Fig. 1). The first reaction step involves the conversion of MoS2 in the presence of a stoichiometric mixture of MoO3 and O2 (from air). The second reaction step takes a portion of the MoO2 product from the first step and further oxidizes it to MoO3 with O2 (from air) to recycle back for further conversion of MoS2 feed. As described elsewhere, a wide range of MoO3 to O2 ratios can be used during the first reaction step [4, 5]; however, for this study, a fixed molar ratio of 4.8:0.6:1.0 MoO3:O2:MoS2 has been chosen (Eq. 1). This ratio was chosen for study because the higher the MoO3:O2 ratio the lower the

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adiabatic reaction temperature, the higher the molybdenum yield to MoO2 and the greater the concentration of the SO2 in the off gas.

MoS2 + 4.8 MoO3 + 0.6 O2 ��������2 + 2 SO2 �o = -151.4 kJ mol-1 (1)

Selectivity of the reaction products to MoO2 over MoO3 and molybdenum suboxides has been shown to be greater than 99.8%, with test work showing residual sulfur in the MoO2 product in the range of 0.02-0.1% [3, 6]. During pilot scale tests, the reaction between a MoS2 concentrate and technical grade MoO3 in an inert atmosphere was performed in a rotary kiln and any larger scale operations must consider mass transfer limitations. It is advantageous that at elevated temperatures the MoO3 will begin to sublime, aiding in the mixing of the reactants. Further, the energy released during the conversion can be used to maintain the heat balance in the sulfide oxidation reactor.

Molybdenum Reoxidation Thermochemistry

In order to run the LSO process as a continuous, closed-loop cycle, the MoO3 consumed during the sulfide oxidation process (Eq. 1) must be regenerated. This is achieved in the second step of the overall process when a fraction of the MoO2 produced – a molar equivalent to the amount of MoO3 originally consumed – is further oxidized in a downer reactor (Eq. 2).

MoO2 + ½ O2 ��MoO3 �o = -313.4 kJ mol-1 (2)

Because this reaction is performed at high temperatures in the absence of sulfur, the enthalpy contained in the off gas can be aggressively captured to improve the overall heat balance of the process. As will be discussed later, consideration must be taken to condense any vaporized MoO3that forms, and the use of a downer furnace will greatly influence the gas-solid mixing.

Process Design Considerations

Due to the expected flotation oil content in the concentrate feed, a deoiler unit has been included to treat the concentrate before blending and conversion. The oil was modeled as n-nonane so that it would be liquid at room temperatures but vaporize at elevated temperatures and an estimate of the heat duty could be made. In actual practice, the recovery of this residual flotation oil is important; the oil that sticks most fervently to the MoS2 is the most effective flotation reagent. In this model, the feed of N2 sweep gas was set to yield an off gas with 50% contained oil vapors.

A rotary kiln was chosen to perform the sulfide oxidation reaction modeling. Laboratory test work has confirmed that the reaction proceeds to less than 0.1% residual sulfur in a rotary kiln, so it is understood that adequate mixing is achieved [3]. The use of a direct fired rotary kiln over an indirect fired rotary kiln was chosen to take advantage of the improved heat balance around the reactor. Additionally, it is understood that the total amount of combustion products produced (CO2 and H2O) would be low since very little fuel is required to maintain kiln temperatures, so off gas dilution and handling would not be significantly impacted. An effort to model the kiln in a countercurrent configuration was made so that the typical “hockey stick” temperature profile might be realized; the idea being that the sudden temperature rise at the end of the kiln will oxidize any remaining sulfur, much in the way MoS2 is roasted at the “tail out” point in a roaster on the lower hearths. Based on modeling configurations to simulate the countercurrent operation of the rotary kiln, heat losses were estimated using HSC 7.1 thermochemical software [7].

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Oxidation of the recycled portion of MoO2 to MoO3 is performed in a downer furnace. The downer furnace is envisioned as a tall column reactor with a high temperature zone established by natural gas combustion at the top. As the particulate MoO2 falls through the high temperature zone, it is well-mixed with preheated reaction air to achieve the rapid and complete conversion to MoO3. As the MoO3 falls the remainder of the distance in the reactor it is cooled by excess air (a total of 300% excess air is introduced to the reactor) to condense any vaporized product. In this model, the downer furnace is simulated as two units, the latter of which handles the cooling and heat loss of the MoO3 and the former of which handles the heat loss associated with the reactor unit.

Heat exchangers have been included throughout the process to recover heat from hot product streams. An effort was made to link heat exchangers in an economical fashion to preheat reaction air whenever possible. As such, air fed to both the rotary kiln and the downer furnace could be sufficiently preheated through heat exchangers operating with an estimated 90% heat transfer efficiency. The excess preheated air could be used in other applications throughout the plant. Alternatively, though not shown here, heat exchangers could be used to recover energy as high pressure steam for electricity generation.

There are three off gas streams to be considered during the process design. The off gas from the deoiler unit has already been discussed. If the oil is to be recovered for recycle to the flotation circuit the oil must be condensed. Alternatively, the off gas should be passed through an afterburner to combust the contained hydrocarbons before venting. The off gas from the rotary kiln is the most critical off gas to handle during the LSO process. Because no excess air is used during the sulfide oxidation process, the dilution of the SO2 in the off gas is minimal. As such, the concentration of SO2 in the off gas can exceed 40 wt. %. Traditionally, the off gas from a multiple hearth roaster is well below 10% SO2 and is processed in a sulfuric acid plant [2].However, at higher SO2 concentrations, it becomes more efficient to produce liquefied SO2instead of H2SO4 because the high concentration off gas requires air dilution before acid processing, increasing the plant capital costs to produce a lower value product. If the market exists, SO2 can be used by several different industries [9]. Therefore, a heat exchanger can be used to initially cool the kiln off gas slightly before downstream processing. The off gas from the downer furnace is substantially free of sulfur (eliminating acid condensation temperaturelimitations) so heat can be recovered from the stream aggressively. After heat recovery, this gas stream can be vented without further treatment.

Model Flow Sheet

The process model for the direct-fire, countercurrent rotary kiln Looping Sulfide Oxidation process is presented in Figure 2, which was built using the SIM module of HSC 7.1 with reaction equilibrium species and compositions determined in FactSage 6.1 thermodynamic software [6, 7]. The heat and material balances around the rotary kiln, downer furnace and heat exchangers are presented in Tables 1-3. An iterative solution to the process model was performed to obtain a MoO2 production rate of 126.59 kg h-1 based on a feed of molybdenum concentrate containing 158 kg h-1 MoS2 (the equivalent of producing ~750,000 kg yr-1 Mo contained) and the reaction stoichiometry specified in Equation 1.

The MoS2 concentrate (187.84 kg h-1) fed to the deoiler is 9.3% gangue (SiO2), 2.8% oil (n-nonane), and 3.7% moisture. The deoiling operation was performed at 300 °C in an N2

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atmosphere to dry the concentrate and vaporize the oil content. The dried concentrate was then transferred to a blender where it was mixed with the recycled MoO3 stream to yield the solids feed for the rotary kiln at 250 °C. Energy losses must be minimized during the transfer of material to lessen the amount of natural gas heating required in the rotary kiln.

Figure 2. HSC 7.1 SIM module flow sheet for LSO process.

The energy released during the exothermic MoS2 oxidation to MoO2 is expected to provide the majority of the energy required to maintain the reaction temperature in the rotary kiln. An objective function was used to define the amount of natural gas required to satisfy the energy balance in the first zone of the rotary kiln. The amount of air fed to the rotary kiln was specified as the stoichiometric amount required to react with the MoS2 according to Eq. 1 plus the amount required to combust the natural gas (Table I). In the second zone of the rotary kiln the temperature was elevated from 650 °C to 700 °C to simulate the countercurrent firing, and another objective function was used to satisfy the energy balance. The air used in the rotary kiln was preheated through a network of heat exchangers to reduce the natural gas heating requirement (Table II). The off gases from the rotary kiln, which require processing due to the SO2 content (46%), are first cooled through a heat exchanger from 700 °C to 300 °C before subsequent treatment, which was not modeled here. The convective energy loss from the rotary kiln was estimated using typical geometries [7].

The hot products from the rotary kiln, which are now largely MoO2 with the impurity gangue, are passed through a solid-gas heat exchanger to recover some of the thermal energy in the stream. The material is cooled to 400 °C before it is transferred to a splitter; the splitter might be a mechanical, pneumatic or other type of equipment capable of handling the hot powder. The purpose of the splitter is to carefully divert the necessary amount of MoO2 from the product stream to the downer furnace for reoxidation. The amount of MoO2 sent to reoxidation must be a molar equivalence to the amount of MoO3 required in the rotary kiln. Based on the stoichiometry specified in Eq. 1, the split fraction going to the downer furnace in the splitter is 82.72%. A lower split fraction (i.e. a higher product:recycle ratio) is possible with alternative

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stoichiometries in Eq. 1. The MoO2 product to be packaged is further cooled to 200 °C through a solid-gas heat exchanger before further air cooling and packaging. This material is expected to be 88% MoO2 with the impurity due to contained gangue.

Table I. Heat and Material Balance around Rotary KilnINPUT Temperature, °C Amount, kg h-1

O2(g) 261 37.93N2(g) 261 124.80CH4(g) 25 4.75MoS2 250 158.00SiO2 250 101.58MoO3 250 680.08Enthalpy -1441.96 kWhOUTPUT Temperature, °C Amount, kg h-1

O2(g) 700 0.01N2(g) 700 124.80CO2(g) 700 13.05H2O(g) 700 10.68SO2(g) 700 126.47SiO2 700 101.58MoO2 700 732.49Enthalpy -1449.20 kWh

Table II. Heat and Material Balance around Downer FurnaceINPUT Temperature, °C Amount, kg h-1

O2(g) 182 330.98N2(g) 182 1094.00CH4(g) 25 7.01MoO2 400 605.91SiO2 400 84.03Enthalpy -1031.07 kWhOUTPUT Temperature, °C Amount, kg h-1

O2(g) 450 227.26N2(g) 450 1094.00CO2(g) 450 19.22H2O(g) 450 15.74SiO2 450 84.03MoO3 450 680.08Enthalpy -1273.39 kWh

Energy loss during transfer of the MoO2 from the splitter to the downer furnace must be minimized to reduce the amount of natural gas heating required in the furnace. The downer furnace model block simulates the oxidation of MoO2 in 300% excess air at 650 °C with necessary heating provided by natural gas combustion (Table III). The temperature should be maintained at relatively low levels to prevent significant sublimation of the MoO3 product. Previous laboratory tests and thermodynamic modeling have shown that this reaction will go to completion [3-6]. The reaction air used in the downer furnace is preheated in a network of heat exchangers (Table II). A second block in the downer furnace, the heat loss block, was used to

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simulate the rapid cooling of the MoO3 product powder as it falls the length of the downer furnace. It was estimated that the product cools to 450 °C before it exists the furnace. The total convection energy loss from the downer furnace was estimated using typical geometries [7]. The off gas from the downer furnace requires no special treatment and can be vented to the atmosphere after cooling through a heat exchanger. The solid product from the downer furnace (Table II) is further cooled to 250 °C through a gas-solid heat exchanger before it is transferred to the blender for recycle.

Table III. Heat and Material Balance around Heat ExchangersHX #1 Amount, kg h-1 Temperature IN, °C Temperature OUT, °COff Gas 275.01 700 300Air 1168.71 168 261HX #2 Amount, kg h-1 Temperature IN, °C Temperature OUT, °CSolids 834.07 700 400Air 1168.71 25 168HX #3 Amount, kg h-1 Temperature IN, °C Temperature OUT, °CSolids 144.14 400 200Air 1703.90 25 35HX #5 Amount, kg h-1 Temperature IN, °C Temperature OUT, °COff Gas 1356.22 450 350Air 1703.90 97 182HX #6 Amount, kg h-1 Temperature IN, °C Temperature OUT, °CSolids 764.10 450 250Air 1703.90 35 97

The volume of preheated air used throughout the LSO process was specified based on the stoichiometry (or percent excess) required at each reactor. Objective functions were then used to calculate the temperature rise of the air through each heat exchanger in order to estimate the temperature of the air as it was introduced to the reactors. The heat exchangers were linked in two separate networks in an effort to maximize energy recovery; a more optimal arrangement could potentially be realized.

Advantages of the Looping Sulfide Oxidation Process

The MoO2 produced during the LSO process has a much lower vapor pressure than MoO3 and requires less reducing agent when it is eventually incorporated into steel melts by end users. Additionally, the essentially complete desulfurization of the molybdenum in the rotary kiln (1) produces a concentrated SO2 off gas from the rotary kiln and (2) allows for aggressive energy capture during MoO2 reoxidation in and after the downer furnace. The rich SO2 off gas from the rotary kiln means a lower capital cost sulfuric acid plant, or economical SO2 liquefaction could be implemented. Because the off gas from the downer furnace is essentially sulfur-free, acid condensation below the dew point will not be an issue, meaning energy can be extracted from the off gas to temperatures below ~300 °C if required. The controlled stoichiometry of the reactions, and the ability to recover energy through the process, makes LSO an inherently low net energy process. In fact, it could in theory operate as a net energy generator [3-5]. Lastly, the equipment specified in this work is simple, commercially available, and cheap. Multiple hearth roasters are complex, large and expensive pieces of equipment; rotary kilns and downer furnaces, on the other hand, are much cheaper capital pieces of equipment and are generally simpler to operate.

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Conclusions

The processing of 100,000 lb yr-1 molybdenum contained MoS2 concentrate to produce MoO2 in the Looping Sulfide Oxidation process has been modeled using thermochemical and thermodynamic software [6, 7]. Estimates for the heat and material balances were made, along with an effort to maximize the energy economy with networks of heat exchangers. In this simulation, the preheating of reaction air positively affected the energy balance to reduce the amount of natural gas heating required. Looping Sulfide Oxidation is a competitive process with conventional multiple hearth roasting, and produces a molybdenum oxide product that is more attractive to end users.

References

[1] LF McHugh, and PL Sallade, Molybdenum Conversion Practice, Metec, Inc.: Winslow NJ, 1977.

[2] CK Gupta, Extractive Metallurgy of Molybdenum, Ann Arbor, MI: CRC Press, 1992.

[3] LF McHugh, R Balliett, and JA Mozolic, The Sulfide Ore Looping Oxidation Process: An Alternative to Current Roasting and Smelting Practice, JOM, July 2008, 84-87.

[4] LF McHugh, LN Shekhter, JD Lessard, DG Gribbin, and E Cankaya-Yalcin, Sulfide Oxidation Process for Production of Molybdenum Oxides from Molybdenite, U.S. Patent Application 13/367,717, filed 18 July 2013.

[5] JD Lessard, LN Shekhter, DG Gribbin, and LF McHugh, Thermodynamic analysis of Looping Sulfide Oxidation production of MoO2 from molybdenite for energy capture and generation, JOM, November 2013, in press.

[6] CW Bale et al., FactSageTM 6.3.1, Thermfact and GTT-Technologies, CRCT, Montreal, Canada (2012).

[7] A Roine et al., HSC 7.11, Outotec, Pori, Finland (2011).

[8] Habashi F, Textbook of Pyrometallurgy, Sainte-Foy, QC: Métallurgie Extractive Québec, 2002.

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