4th International Symposium on High-Temperature Metallurgical Processing

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4th International Symposium on High-Temperature Metallurgical Processing

Proceedings of a symposium sponsored by the Pyrometallurgy Committee and

the Energy Committee of the Extraction and Processing Division of

TMS (The Minerals, Metals & Materials Society)

Held during the TMS 2013 Annual Meeting & Exhibition

San Antonio, Texas, USA March 3-7, 2013

Edited by

Tao Jiang Jiann-Yang Hwang Phillip J. Mackey

Onuralp Yucel Guifeng Zhou

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TABLE OF CONTENTS 4th International Symposium on High-Temperature Metallurgical Processing

Preface xiii About the Editors xv

High Efficiency New Metallurgical Technology

A New Copper Smelting Technology - Bottom Blown Oxygen Furnace Developed at Dongying Fangyuan Nonferrous Metals 3

B. Zhao, Z. Cui, and Z. Wang

A Novel Vacuum Aluminothermic Reduction Lithium Process 11 Y. Di, Z. Wang, S. Tao, andN. Feng

Study on Double-Layered Pellet Roasting of Sulfur and Arsenic-Bearing Gold Concentrate 19

T. Jiang, X. Li, J. Ge, L. Cui, Q. Li, and Y. Yang

Preparation of M00 3 from Ammonium Tetramolybdate in Microwave Fields 27

J. Li, L. Zhang, G Chen, J. Peng, B. Liu, and H. Xia

Looping Sulfide Oxidation™ Process for Anode Copper Production 37 L. Shekhter, C. Anderson, D. Gribbin, E. Cankaya-Yalcin, J. Lessard, and L. McHugh

Direct Redaction of TI-V Magnetite Via ITmk3 Technology 45 N. Panishev, B. Dubrovsky, A. Starikov, E. Redin, andE. Knyazev

Research and Industrial Application of Oxygen-rich Side-blow Bath Smelting Technology 49

L. Chen, W. Bin, T. Yang, W. Liu, and S. Bin

Thermal Plasma Torches for Metallurgical Applications 57 L. Rao, F. Rivard, and P. Carabin

v

Research on Removal of Potassium and Sodium by Pre-reduction Sintering 67 Q. Li, Z. Jing, Y. Yang, T. Jiang, G Li, andX. Chen

Fundamental Research of Metallurgical Process

Reaction Mechanisms and Product Morphologies on Gaseous Reduction of Metal Compounds - Extractive Metallurgy Meets Materials Science 77

P. Hayes

Research on the Slag Phase Type of Vanadium-Titanium Magnetite in Pre-Reduction-Electric Furnace Smelting 87

Y. Guo, M. Tang, T. Jiang, L. Qing, and J. Zhou

Density of CaO-5%MgO-Al203-Si02 Slag with Low Silica 95 J. Li, T. Zeng, J. Xu, C. Jie, J. Zhang, and K. Chou

Study on Magnetic Roasting Kinetic of Oolitic Hematite 103 Y. Guo, L. Qing, T. Jiang, L. Yang, S. Liu, M. Tang, X. Song, andJ. Zhou

Basic Research on External Desulfurization of Hot Iron by Dolomite I l l X. Ren, T. Zhang, Y. Liu, Z. Dou, and G Lv

Iron-Carbon Nuggets Coalescence: Influence of Slag's Liquidus Temperatures 117

A. Nogueira, C. Takano, M. Mourào, and A. Pillihuaman

Effect of Mixed Charge of Ore and Lump Coal on the Softening-Melting Property of the Burden 125

H. Guo, G Yang, J. Zhang, J. Shao, Y. Fu, and D. Wan

Effects of Oxygen Content and Roasting Temperature on the Sintering Mineralization Properties of Different Iron Ores 131

X. Mao, Z. You, Y. Zhang, Z. Fan, and T. Jiang

Analysis on Wear Mechanism of Refractories Used in Hot Air Pipeline for Large Scale Blast Furnaces 139

G Xu, X. Chen, X. Huang, W. Xiang, and H Zhang

VI

Alloy and Materials Preparation I

Hot Workability of M42 Tool Steel Additionally Alloyed with Co and Mo ....147 M. Tercelj, G Kugler, M. Fazarinc, and I. Perm

Effects of Crystallization of Mould Fluxes on Property of Liquid Slag Film and Its Impact onPeritectic Steel Slab Continuous Casting 155

X. Long, S. He, L. Zhu, T. Wu, and Q. Wang

Hot Ductility of Nb-V Containing Microalloyed Steel during Solidification...163 Y. Sun, Y. Zeng, andK. Cai

Co-Cr-Mo Alloys Production by Self Propagating High Temperature Synthesis 171

O. Okur, M. Alkan, and O. Yiicel

High-Temperature Oxidation and Corrosion Behaviors of Ni-Fe-Cr Alloy for Inert Anode Materials in Aluminum Electrolysis 177

J. Xue, L. Feng, G Ndong, J. Zhu, and Q. Liu

Production of Molybdenum Containing Iron Based Alloys via Metallothermic Processes 185

D. Kirgöz, M. Alkan, and O. Yiicel

Electrical Resistance of TiB2-C/C Function Gradient Materials for Aluminum Reduction Cathodes 191

J. Zhu, J. Xue, and B. Li

Experimental Study of Phosphorus Distribution Between Slag and Metal during Duplex Dephosphorus Converter Processing 199

X. Qiu, B. Xie, L. Jiang, X. Zhang, J. Diao, and H. Li

The Effect of Aluminum Addition to the ESR Process Slag on IN718 Superalloy Characteristics 207

A. Sheikhhosseini, and S. Abbasi

Alloy and Materials Preparation II

Production of Fe-Based Alloys by Metall othermic Reduction of Mill Scales from Continuous Casting Processes 219

M. Bugdayci, M. Alkan, and O. Yiicel

Study of Heat Flux in CSP Continuous Casting Mold 227 W. Yang, X. Wang, L. Zhang, D. Yang, andX. Liu

vn

The Effect of Thermomechanical Ageing of Aluminium-Copper Alloy (MATLAB Approach) 239

A. Amos, G Akeem, F. Emmanuel, O. Ajibade, and O. Oladayo

Research on Inclusions in CuCr Alloy Prepared by Thermit Reduction 247 Z. Dou, T. Zhang, G Shi, Y. Du, L. Niu, G Lv, Y. Liu, and J. He

Copper-Based Multi-Component Alloys by Vacuum Distillation to Separate Copper Enriched Lead, Silver and Other Valuable Metals Research 255

H. Xiong, B. Yang, D. Liu, B. Xu, X. Chen, and Y. Deng

An Overview of Research on Au & Ag Recovery in Copper Smelter 265 Y. Shi, and Z. Ye

The Analysis of Orthogonal Experiment Method of Carbon-Coated LiNi1/3Mn1/3Co1/302 via Microwave-pyrolysis Method 277

Y. Han, Z. Zhang, L. Zhang, J. Peng, and M. Fu

Comparative Study on the Metal Aluminum Produced from Alumina by Carbothermic Reduction and Carbothermic-Chlorination 287

Q. Yu, B. Yang, Y. Deng, F. Wang, H Xiong, and M. Chen

Continuously Synthesis and Performance of Cathode Material LiNi1/3Co1/3Mn1/302 for Lithium Ion Batteries 293

M. Fu, L. Zhang, Z. Zhang, J. Peng, Y. Han, and J. Du

Tensile Mechanical Properties and Brittle Effect of Austempered Cr-Mo Alloy Steel 299

C Chen, F. Hung, T. Lui, and L. Chen

Roasting, Reduction and Smelting

Cost Benefits of EAF Bottom Purging Systems Due to Metallurgical Improvements 309

M. Kirschen, A. Hanna, andK. Zettl

Researches on Reduction Roasting of Low-Grade Manganese Oxide Ores Using Biomass Charcoal asReductant 317

Y. Zhang, D. Duan, Z. You, G Li, X. Fan, and T. Jiang

Reduction Behavior of Pellets Balled with Bentonite 325 T. Jiang, G Han, Y. Huang, G Li, and Y. Zhang

vin

Vanadium Distribution Between Blast Furnace Slag and Hot Metal 333 J. Yan, B. Xie, X. Zeng, Q. Huang, and H. Li

Development of Antimony Smelting Technology in China 341 W. Liu, T. Yang, L. Chen, S. Bin, and W. Bin

Effect of Reduction Conditons on Pre-reduction Behaviors of Self-fluxed Pellets in COREX Process 353

D. Zhu, Z. Gao, and J. Pan

Calcination Factors of Rubidium Extraction from Low-Grade Muscovite Ore 361

Z Shan, X. Shu, J. Feng, and W. Zhou

Reduction and Separation of High Iron Content Manganese Ore and Its Mechanism 367

Z Huang, B. Chai, L. Yi, and T. Jiang

Simulation and Modeling

Simulations for Optimising Plant Flowsheets for Brownfield Improvements ..379 A. Campbell, and M. Reed

Study on Apprasial Model of Iron Ores Based on Multi-level Fuzzy Comprehensive Evaluation 385

X. Fan, Y. Li, andX. Chen

The Numerical Simulation and Application of Oxygen Lance in 120t BOF of PANSTEEL 393

Y. Chen, X. Liang, J. Zeng, G. LI, and S. Yang

CFD Model Development for Gaseous Reduction of Iron Ore Fines Using Multilayer Moving-fluidized Bed 401

H. Tang, Y. Mao, L. Ma, and Z. Guo

Deformation Simulation of Copper Plates of Slab Continuous Casting Mold 411

X. Meng, W. Wang, M. Zhu, and R. Suzuki

An Estimation Model for the Viscosities of CaF2-(CaO)-Al203 Slags 417 G Shi, T. Zhang, L. Niu, and Z. Dou

IX

Thermodynamic Modeling of the CaO-FetO-CaF2 System for Application In Electroslag Remelting 425

D. Nassyrov, and I. Jung

Determination of Liquidus Temperatures from Viscosity for CaO-Al203

Based Slags 435 J. Xu, L. Tang, M. Sheng, J. Li, J. Zhang, and K. Wan

Numerical Simulation of Electromagnetic Fields in Microwave Gas Heating System: Influence of the Dielectric Properties 443

X. Shang, J. Chen, N. Shen, Y. Shi, B. Zhang, G Chen, and J. Peng

Sintering and Pelletization

Production of Crude Ferronickel from Sivrihisar Latérite Ores of Turkey 453 E. Keskinkilic, S. Pournaderi, A. Geveci, and Y. Topkaya

Sintering Process of Phosphorite from Leshan,China 461 E. Guo, D. Li, C. Pan, M. Liu, andX. Lv

Comprehensive Effect of Coke Breeze and Limestone Particle Size on Sinter Performance in Sintering of a Coarse Hematite Iron Ore 469

Z. Wang, J. Zhang, X. Xing, S. Ren, B. Gao, andX. Zhang

Effects of the Raw Material Characteristics of Iron Concentrates on Ballability 477

J. Pan, S. Yue, D. Zhu, and Z. He

Study on Improving the Strength of Copper Concentrate Pellets by Adding Binders 485

X. Fan, S. He, L. Zhang, Y. Tang, X. Chen, M. Gan, and G Bai

Sintering Process of Chromite Concentrate 493 P. Chen, D. Li, C. Pan, M. Liu, andX. Lv

Research on Strengthening Consolidation of Magnesium Bearing Hematite Pellets 501

L. Yuan, X. Fan, M. Gan, G Yang, X. Huang, Z. Ji, and Z. Yu

Study on the Improvements of Reduction Swellability and Low Temperature Reduction Disintegration of Vanadium-Titanium Magnetite Oxidized Pellets 509

Y. Guo, J. Zhou, T Jiang, F. Chen, X. Song, M. Tang, and L. Qing

x

The New On-line Detecting Method of Sintering Mix and Its Basic Research 517

Y. Yang, Q. Tan, Q. Li, K. Li, Y. Zhu, D. Li, Q. Xie, and C. Li

Optimizing the Sintering Process of Low-Grade Ferromanganese Ores 527 Y. Zhang, W. Luo, Z. You, Z. Su, G. Li, and T. Jiang

Treatment of Solid Slag/Wastes and Complex Ores

Using of Spent Foundry Sands for Production of Burned Ceramic Building Materials: Influence for Environment 537

M. Holtzer, J. Danko, R. Danko, and S. Zymankowska-Kumon

Developments of Processing Technologies for Refractory Gold Ores 545 L. Chen, T. Yang, W. Liu, and D. Wang

Study on Iron Recovery and Desulfurization of Pyrite Cinder 553 X. Fan, H. Wen, Q. Deng, M. Gan, G Shen, and S. Huang

Reaction Process of Coal Based Reduction of Siderite Ore 563 J. Pan, Z. Xue, D. Zhu, X. Zhou, and Y. Luo

Enhanced Reduction of CaF2 and NaF on Vanadium Titano-Magnetite Carbon Composite Pellets 571

X. Xing, J. Zhang, Z. Wang, S. Ren, M. Cao, Z. Liu, and M. Lu

An Investigation on Utilization of Ferrous Scrap by Could-Bonded Pelletizing579 X. Fan, L. Yuan, M. Gan, W. Lv, Y. Wang, andX. Chen

Research on the Lead Removal from Pyrity Cinder 587 X. Chen, G Shen, X. Fan, Q. Deng, H. Wen, and M. Gan

Microwave Heating, Energy and Environment

Microwave Reflection Loss of Ferric Oxide 597 Z. Peng, J. Hwang, B. Kim, M. Andriese, andX. Wang

Process Optimization by Response Surface Method for Sintering of Chromite Fines by Microwave 605

J. Chen, H Zhu, J. Peng, S. Guo, L. Dai, and Q. Ye

Life Cycle Assessment of Microwave Hot Air Systems 615 J. Chen, G Chen, and J. Peng

XI

Chemical Enrichment of Precious Metals in Iron Sulfides Using Microwave Energy 623

M. Andriese, J. Hwang, Z. Peng, and B. Li

Development of Bismuth Smelting Technology in China 631 T. Yang, J. Li, W. Liu, L. Chen, and W. Bin

Research on the Influence of Moulding Sand with Furan Resin on the Environment 643

M. Holtzer, M. Kubecki, R. Danko, S. Zymankowska-Kumon, and A. Bobrowski

Prediction Method of Pre-Ignition Bed Pressure Drop in Composite Agglomeration Process 651

H. Zhang, H. Yu, Z. Yu, Y. Zhang, G. Li, and T. Jiang

Co-Gasification Behavior of Metallurgical Coke with High and Low Reactivity 659

H. Zuo, B. Gao, J. Zhang, and Z. Wang

Study on Swelling Behavior of Iron Ore Pellets in Direct Reduction with Coal Gas 667

Z. Huang, Z. Liang, L. Yi, and T. Jiang

Author Index 675

Subject Index 679

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Preface

This book collects selected papers presented at the 4th International Symposium on High-Temperature Metallurgical Processing organized in conjunction with the TMS 2013 Annual Meeting & Exhibition in San Antonio, Texas, USA.

As the title of symposium suggests it is 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 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 such as handling and treatment of emission gas and by-products. Since 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 temperature.

Over 350 authors have contributed to the symposium with a total of 123 presentations. After reviewing the submitted manuscripts, more than 80 papers were accepted for publication on this book. The book is divided into nine sections: High Efficiency New Metallurgical Technology; Fundamental Research of Metallurgical Process; Alloy and Materials Preparation; Roasting, Reduction and Smelting; Simulation and Modeling; Treatment and Recycling of Solid Slag/Wastes; Microwave Heating; Energy and Environment; and Agglomeration and Raw Materials Processing.

This is the third 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.

There could not be this book without contributions from the authors of included papers, time and effort that reviewers dedicated to the manuscripts, and help from the publisher. We thank them all! We also want to thank Ms. Yanfang Huang and Ms. Feng Chen for their assistance in collating the submitted abstracts and manuscripts.

Tao Jiang,

Jiann-Yang Hwang,

Phillip J. Mackey,

Onuralp Yucel,

and Guifeng Zhou

xin

Editors

Tao Jiang was born in 1963 in Anhui, China. He received his M.S. in 1986 and Ph.D. in 1990, both from Central South University of Technology. Then he joined the university and served as an assistant professor (1990-1992) and full professor (1992-2000). From 2000 to 2003, he was a visiting scientist to the Department of Metallurgical Engineering, 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 appointed the dean of the school from 2010.

Some of his current research activities include beneficiation, agglomeration, reduction of complex iron ores, and extraction of refractory gold ores. Dr. Jiang has more than 30 conference presentations and has published 310 technical papers, 6 books including "Direct Reduction of Composite Binder Pellets and Use of DPJ", "Principle and Technology of Agglomeration of Iron Ores", "Chemistry of Extractive Metallurgy of Gold", and "Electrochemistry and Technology of Catalytical Leaching of Gold". He has won two China national science and technology prizes and 29 patents for the research and development in the field of reduction and agglomeration of iron ores.

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

Jiann-Yang (Jim) Hwang is a Professor in the Department of Materials Science and Engineering at Michigan Technological University. He is also the Chief Energy and Environment 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 Science and Technology Beijing, Chongqing University, and Kunming University of Science and Technology.

xv

Dr. Hwang received his B.S. degree from National Cheng Kung University 1974, M.S. in 1980 and Ph.D. in 1982, both from Purdue University. He joined Michigan Technological University in 1984 and has served as its Director of the Institute of Materials 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 patents, 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 symposiums.

Phillip J. Mackey is a consulting metallurgical engineer and specialist in non-ferrous metals with over forty years of international experience in all aspects of the non-ferrous and ferrous metals business. Dr. Mackey is originally from Australia where he received his Ph.D. in metallurgical engineering from the University of New South Wales studying under Professor N. A. Warner, one of the innovative leaders of the time. Dr. Mackey's first challenge was at Noranda Mines in Canada in process development and piloting a revolutionary new copper smelting process. In this work, he 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 technologies developed in the twentieth century. He was also responsible for the marketing of this technology at a number of other companies worldwide. Dr. Mackey was a key developer of the Noranda Continuous Converter.

He was also involved in a number of nickel sulphide and nickel latérite projects around the world. He has authored or co-authored over 100 publications covering many aspects of non-ferrous metallurgy. Active in the copper world, he one of the co-founders of the Copper/Cobre series of international conferences 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. Phillip is a MetSoc Past-President ( 1984-1985) and a Fellow of both CM and TMS. A recipient of several professional awards in Canada and the United States, he was awarded the Selwyn G. Blaylock Medal of the CDVI in 2010 and received the Airey Award by The Metallurgical Society of CIM in 2012.

xvi

1

Onuralp Yücel was born in 1961 in Diyarbakir, Turkey. He completed his technical education with a Ph.D. in Metallurgical Engineering from Istanbul Technical University (ITU) where he has held the post of Professor since 2002. He was a Visiting Scientist in Berlin Technical University between 1987 and 1988. He carried out Post Doctoral Studies at New Mexico Institute of Mining and Technology, Socorro, USA between 1993 and 1994. Prof. Yücel has as many as 200 publications/presentations to his credit, which include topics like, technological developments in the production of wide range of metals, ferroalloys, advanced ceramic powders and application of carbothermic and metalothermic processes among others. He was the vice chairman of ITU, Metallurgical and Materials Engineering Department between 2004 and 2007. He has been a director of ITU, Applied Research Center of Material Science & Production Technologies between 2006 and 2012.

Guifeng Zhou received his B.S. degree in Materials Science and Engineering from the Northwest Industry University (China) in 1984, his M.S. degree in Materials and Heat Treatment from the Hua Zhong University of Science and Technology in 1990, and earned his Ph.D. degree in Materials Physics and Chemistry from the University of Science and Technology Beijing in 2000. For a year and a half as an senior visiting scholar did some research regarding microalloying technology at University of Pittsburgh.

Dr. Zhou is vice director of R&D center of Wuhan iron & Steel (Group) Corp., also is a professor and supervisor of Ph.D. of Wuhan University Of Science and Technology. His work concentrated on new steel product development, microstructure and mechanical property of materials. Dr. Zhou has published over 20 technical papers, holds 4 patents, won progress prize in science and technology by Nation three times, is an expert with State Department special allowance, also is a member of editorial board of Research on Iron and Steel, is the member of the Chinese Metals Society, the Quality Control Society of China and the Science and Technology Association.

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4th International Symposium on High-Temperature Metallurgical Processing

High Efficiency New Metallurgical Technology

Session Chairs: Tao Jiang

Lawrence F. McHugh

4th International Symposium on High-Temperature Metallurgical Processing Edited by: Tao Jiang, Jiann-YangHwang, Phillip J. Mackey, Onuralp Yucel, and Guifeng Zhou

TMS (The Minerals, Metals & Materials Society), 2013

A NEW COPPER SMELTING TECHNOLOGY - BOTTOM BLOWN OXYGEN FURNACE DEVELOPED AT DONGYING FANGYUAN

NONFERROUS METALS

Baojun Zhao , Zhixiang Cui , Zhi Wang

School of Chemical Engineering, The University of Queensland, Brisbane, Australia Dongying Fangyuan Nonferrous Metals Co., Ltd, Dongying City, China

Keywords: Copper smelting, Bottom blown, Slag, Autothermal operation

Abstract

Bottom blown oxygen copper smelting process has been developed in Dongying, China by Dongying Fangyuan Nonferrous Metals Co., Ltd. in commercial scale. This is the first modern copper smelting technology developed in China with the advantages of high oxygen enrichment, low temperature and autothermal operation. Production capacity of more than 100,000 tonnes per year of copper has been achieved through a single bottom blown oxygen furnace with instantaneous feed rates reaching up to 90 t/h. The main features of the bottom blowing smelting process are that high grade matte (up to 72 wt% Cu) can be produced at relatively low temperatures with 2-3 wt% Cu remaining in the smelting slag. Analyses of quenched smelting slag show that significant amount of magnetite crystals are present in the slags at operating temperature which indicates that the operating temperature was much lower than the liquidus temperature of the slag. After four years operation this new technology has shown great potential for expanding production capability and energy saving. Process development continues on the first commercial scale bottom blown furnace at Dongying Fangyuan Nonferrous Metals and a larger bottom blown smelting furnace is under construction.

Introduction

Flash and bath smelting technologies are the major processes used in modern copper making industry [1]. Ausmelt/Isasmelt using top blown and Noranda/Teniente using side blown are typical and common bath smelting technologies. In 1980s-1990s Hunan Shuikoshan Mineral Bureau, jointly with China Nonferrous Engineering and Research Institute (now China Enfi Engineering Corp.), developed the concepts of the bottom blown oxygen processes for both lead and copper smelting [2]. After the pilot test on 3000 ton copper per year scale in 1991, it was not progressed to industrial scope.

Dongying Fangyuan Nonferrous Metals Co., Ltd. was established in 1998 to produce electrolytic copper from scrap. It was in 2005 the company decided to expand its production capacity by introducing smelting-converting technology to produce blister copper from concentrate. The target was to find new technologies that could be applied to 1) treat low grade complex copper concentrate; 2) to recover not only copper but also other valuable metals such as gold and silver; 3) to produce off-gases with higher SO2 concentration for acid plant and 4) to have low operating costs while improving the environmental performance.

After systematic investigations and comparisons the bottom blown oxygen technology was finally selected for copper smelting although there appeared to be risks to increase the scope from 3000 t/year directly to 100,000 t/year. The operation commenced on the end of 2008 and

3

has been running for almost four years. During 4 years developing and operating the bottom blown oxygen technology on large scale, significant technical improvements have been achieved in areas such as oxygen lance design, feed preparation, off-gas handling, operating and process control strategies, refractory management, operator training and commissioning systems. This paper summaries the main features and operating experiences on the first commercial bottom blown oxygen furnace in the World developed at Dongying Fangyuan Nonferrous Metals Co., Ltd.

Bottom blown oxygen technology

Bottom blown oxygen smelting - PS rotary furnace converting - electrolysis refining is the process adopted at Dongying Fangyuan Nonferrous Metals for production of blister copper. The converting and refining technologies are commonly used in copper industry and similar to other plants. It is focused only on bottom blown oxygen smelting technology in this paper.

Description of the Technology

Mixed feed materials with 7-10 wt% moisture are continuously transported by a belt conveyor into a high temperature melt in the furnace through the feed mouth located above the reaction zone. Oxygen and air are blown constantly by the oxygen lances into melting copper matte, in which iron and sulfur are rapidly oxidized and slag is also formed. Sulfur dioxide produced is directed through the waste-heat boiler and electric precipitation, then led into the acid plant to produce sulfuric acid. Slag formed in the furnace can be tapped regularly through a taphole at the end of the furnace, lifted by a ladle to the slag site for slow cooling, followed by the flotation process to recover copper. Matte formed in the furnace is tapped regularly through a taphole on the middle part of the furnace, lifted by a ladle into the PS converter.

Figure 1 : The bottom blown furnace at Dongying Fangyuan Nonferrous Metals

The main equipment is a horizontal cylindrical furnace shown in Figure 1. The size of the furnace is <t> 4.4x 16.5 m and it is lined with 380 mm thick chrome-magnesia bricks. The bottom blown furnace has 9 oxygen lances arranged in two rows on the bottom. The lower row with 5 lances sloping towards the outside at 7 degrees, the upper row with 4 lances towards the outside at 22 degrees so that the angle between the two rows is 15 degrees. Each lance consists of an inside tube and an external shroud. The inside tube delivers pure oxygen and shroud delivers air flow as coolant. The furnace is equipped with a rotation mechanism to be used to roll the lances

4

above the liquids during maintenance and repair. It also rolls the lances above the liquids in the event of a power failure or other emergency. The oxygen plant has a capability of 10,000 Nm3/h oxygen supply using a deep cooling system. The off-gas system can treat 120,000 Nm /h gas to match the acid plant. Three PS converters of the size <t> 3.8x8.1 m are used to treat the matte produced by the bottom blown furnace.

Reaction Mechanisms

The reaction mechanisms in the bottom blown furnace are:

1) Oxygen injected from the bottom of the furnace reacts with matte

2Cu2S + 30 2 = 2Cu20 + 2S02 (1)

3FeS + 502 = Fe304 + 3S02 (2)

2) Sulfide concentrate is dropped onto the surface of the agitated mixed slag-matte melt and enter the matte layer where they are oxidized by Cu20 and Fe3Û4

FeS + Cu20 = Cu2S + FeO (3)

FeS + 3Fe304 = lOFeO +S02 (4)

3) Iron oxides from the oxidation react with Si02 flux to form slag, which rises to the top of the bath

4) S02 from the oxidation rises through the bath and leaves the furnace along with other gases.

One of the main features of the bottom blown process is that most of the oxidization reactions take place in matte phase. The oxygen injected from the bottom of the furnace has to travel through the matte and slag bath so that almost all oxygen can be consumed within the bath.

Separation of Matte and Slag

Matte and slag are intimately mixed in the reaction zone above the oxygen lances. They are then allowed to separate in a relatively quiet lance-free zone at the taphole end of the furnace. Gradually the matte droplets settle, S02-rich gas rises, and slag forms a top layer of the melt for tapping from the furnace. The matte is tapped from the bottom of the furnace and sent to the PS converters immediately. The slag is sent for Cu recovery by solidification/comminution/flotation process.

Process Parameters

Table I shows key process parameters at Fangyuan smelting plant for January 2012 compared with the initial design. It can be seen that the average concentrate feed rate has been increased from initially designed 32 to the current 70 dry t/h. This means that the productivity has been doubled as a result of extensive technique development at Dongying Fangyuan Nonferrous Metals. The current feed rate is limited by the capability of oxygen production and acid plant. It is expected that more concentrate can be treated in the bottom blown furnace with expanded oxygen and acid plants.

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Table I. Typical process parameters for Fangyuan smelting plant for January 2012 Parameter

Maximum concentrate feed rate

Average concentrate feed rate

Average Cu content in concentrate

Average moisture of the feed

Average silica flux feed rate

Average coal feed rate

Total average feed to the furnace

Average copper matte grade

Average Fe/SiC>2 in slag

Average Cu in smelting slag

Average Cu in flotation tailing slag

Average oxygen+air flow rate

Average oxygen enrichment

Bath temperature range

Unit

dryt/h

dryt/h

%

%

dryt/h

dryt/h

wet t/h

%

%

%

Nm'/s

%

°C

Value - design

32

32

25

8

2.46

55

1.7

4

0.42

70

1180-1200

Value - 2012

75

70

22

7

8

0-0.8

90

70

1.8

2.6

0.3

4.2

72

1150-1170

Slag Chemistry

Quenched slag samples have been collected from the bottom blown furnace at Dongying Fangyuan Nonferrous Metals. The samples were mounted and polished for examination using Electron Probe X-Ray Microanalysis (EPMA). Typical microstructures of the smelting slags and compositions of the phases present in the samples were measured using a JEOL JXA-8200 electron probe X-ray microanalyser with wavelength dispersive detectors. (JEOL is a trademark of Japan Electron Optics Ltd., Tokyo). An accelerating voltage of 15 KV and a probe current of 15 nAmps were used. The Duncumb-Philibert ZAF correction procedure supplied with JEOL-8200 was applied. The average accuracy of the EPMA measurements was estimated to be within ± 1 weight percent.

The typical microstructures of a bottom blown smelting slag are shown in Figure 2. It is clear that during sampling the section close to the metal bar was cooled faster than other sections. Rapid cooled areas are shown in Figure 2b. The microstructures in rapidly cooled areas will be close to those at temperature. On rapid cooling the liquid phase was transformed as glass and the solid phases remained their shapes and compositions. It can be seen from Figure 2 that liquid, spinel and matte phases were present in the copper smelting slag. The sizes and shapes of the spinel phase indicate that these crystals were present at operating temperature, not formed on cooling. The proportion of the spinel phase present in the slag at operating temperature was estimated to be 20% in volume from its microstructures. This indicates that the slag temperature

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was much lower than its liquidus temperature. It can be seen from Figure 2 that matte droplets in different sizes are dispersed throughout the slag in all parts of the sample.

The compositions of the phases present in the slag were measured by EPMA and the results are given in Table II. The bilk composition of the slag was analysed with XRF by ALS Laboratory Group (Brisbane, Australia). Both EPMA and XRF can only analyse elemental compositions. The oxidation states of the oxides given in Table II are for presentation purpose. It is important to determine the Fe +/Fe + ratio in the slag. The Fe + concentration was obtained by potassium dichromate titration at ALS Laboratory. The FeO concentration was determined to be 40.7 wt% for the slag given in Table II and the Fe2C>3 concentration is 21.5 wt%. Note that the bulk composition of the slag analysed by XRF includes glass, spinel and matte phases.

(a) (b) Figure 2. Typical microstructures of quenched smelting slag from Fangyuan bottom blown

furnace, G = glass; M = matte; R = resin; S = spinel

It can be seen from Table II that the Fe/SiC>2 weight ratio in the slag is 2.0. A pseudo-binary phase diagram calculated by FactSage 6.2 [3] is shown in Figure 3 for the slag composition given in Table II assuming P02 =10" atm. It can be seen that spinel and silica are the primary phases in the composition range calculated. There is a minimum liquidus temperature occurring at Fe/SiC>2 ratio of 1.2. In spinel primary phase field the liquidus temperatures increase slowly with increasing Fe/SiC>2 ratio. The bottom blown smelting slag given in Table II is estimated to have a liquidus temperature of 1240 °C from Figure 3 at P02 = 10" atm. From the bulk composition measured by XRF and the compositions of the phases measured by EPMA it is possible to calculate the proportion of each phase by mass balance. The proportions of glass, spinel and matte are calculated to be 79.5, 16.8 and 3.7 wt% respectively.

It can be seen from Table II that significant AI2O3 and ZnO are also present in the slag, in addition to "FeO" and SiC>2. FactSage predictions show that these components can increase liquidus temperature of the slag. The spinel phase contains mainly iron oxide (93.7 wt%). However, significant amount of AI2O3 and ZnO are also present in the spinel that are higher than predicted by FactSage. Again from mass balance it can be calculated that approximately 20 wt% copper is dissolved in the slag and 80 wt% copper is physically entrained in the slag as matte droplets.

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Table IL Phases bulk-XRF glass spinel matte

Compositions of phases "FeO" 62.2 58.4 93.7 10.1

Cu20 3.2 0.8 0.1 68.9

CaO 1.0 1.2 0.0 0.0

present in copper smelting slag Si02

24.2 30.5 0.6 0.0

A1203

3.1 3.2 3.4 0.0

As203

0.1 0.1 0.0 0.1

MgO 0.6 0.7 0.3 0.0

, analysed by EPMA (wt%) S

1.7 1.1 0.0

20.3

PbO 0.5 0.5 0.1 0.1

ZnO 3.1 3.3 1.7 0.2

Mo03

0.2 0.2 0.1 0.3

1600

<u 1500

1400

<u 1300

1200

1100

Si02 \

3.2wt%AI203

l . lwt%CaO 0.6wt%MgO 0.5 wt% PbO 3.3wt%ZnO Po, = 108 atm

"""""^ spinel

0.5 1.0 1.5 2.0 2.5 3.0

Fe/Si02 (weight)

Figure 3. Liquidus temperature as a function of Fe/SiC>2 ratio at fixed P02 and constant ratios of other components, calculated by FactSage 6.2

100

? 80

;c §■ 60

M -

= 40 "+J

§. 20 0

Q.

0

11

Experimental

1 22.7wt%Fe203

/ 43.0 wt% FeO . / 25.6wt%Si02

/FactSage 6.2 l . lwt%CaO / 0.6wt%MgO

' 0.5 wt% PbO , , , 3.3wt%£nO

00 1150 1200 1250 1300 1350 14 00

Temperature (°C)

Figure 4. Proportion of liquid as a function of temperature for a typical bottom blown smelting slag, comparison between experimental results and FactSage 6.2 predictions

Reheating experiments have been carried out from the slag shown in Table II under ultra-high purity Ar flow. The experiments were carried out at 1150, 1200, 1250 and 1300 °C respectively using Pt foil. In these experiments the oxygen partial pressure was not controlled and it was assumed that there was no oxygen exchange between the slag and gas. In this case FactSage predictions show that the oxygen partial pressures increase with increasing temperature. EPMA show that the solid spinel phase is still present at 1300 °C. Experimentally determined proportion

of liquid phase from mass balance is compared with FactSage predictions (Figure 4). It can be seen from Figure 4 that the present study confirms the FactSage predictions and they both show that proportion of liquid phase increase slowly with increasing temperature between 1150 and 1300 °C. However, FactSage predictions indicate that the proportion of liquid phase will decrease sharply if the temperature is below 1150 °C due to formation of other solid phases such as olivine and pyroxene.

Advantages of the Bottom Blown Oxygen Smelting Process

Bottom blown furnace is one of the bath smelting technologies. It has shown a lot of advantages such as suitability for a wide range of copper, gold and silver concentrates, minimal feed preparation and quiet operation environment. In addition, many other advantages have been demonstrated due to its unique design and these are briefly described as follows.

High Oxygen Enrichment Each lance in the bottom blown furnace is equipped with an inside tube and an external shroud. High pressure pure oxygen is injected through the tube in the center and air is injected through the shroud as coolant. Pure oxygen and air are not premixed so that the pure oxygen and the oxygen in air react with the matte independently. For this reason the lances on the bottom are called "oxygen lances". It is expected that the reaction between pure oxygen and matte is much faster than the oxygen-enriched air. Further studies are required to evaluate the behavior of pure oxygen in copper smelting reactions.

High Oxygen Pressure and Long Oxygen Lance Life As one of significant development at Dongying Fangyuan Nonferrous Metals, a series of trials have been undertaken to identify optimum pressures of the oxygen and air in the lances. It was found that optimum pressures are determined by the feed rate, viscosity of slag, thicknesses of slag and matte layers. The following requirements need to be met: 1 ) no backflow of matte into the oxygen lances; 2) enough stirring for rapid reaction and generation of wave; 3) not over splashing slag and matte to block the feed mouth and 4) a protection accretion is formed at the tip of the oxygen lance. Figure 5 shows the "accretion" formed at the tip of the lance which enable the lance life to be over 10 months. It can be seen from Figure 5 that the sizes of the accretion are different indicating the conditions to control the accretion need to be refined.

Figure 5. Oxygen lance "accretion"

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The design of the bottom blown furnace allows much high gas pressure to be used which has the advantages of 1) strongly agitating the melt for rapid reactions; 2) generating melt waves to help the settlement of the matte droplets and the tapping of the slag; 3) forming the accretion to protect the lance so that tuyere puncher is never required; 4) potentially expanding the productivity which is currently limited by the availability of oxygen.

Low Temperature Smelting The slag temperatures measured in the taphole of the Fangyuan bottom blown furnace are usually in the range of 1150 to 1170 °C. It has demonstrated in the previous sections that the liquidus temperature of the smelting slag is above 1300 °C due to its high Fe/SiC>2 ratio. This means that the bottom blown furnace can operate at a relatively much lower temperature than the slag liquidus which is not possible in other technologies. The main reason for the low temperature operation to be possible is that bottom blown high pressure gases can generate surface waves of the bath. These waves are beneficial in pushing the spinel-containing slag out of the taphole and in forming large droplet from the smaller matte droplets. As a result, high viscosity slag can be tapped smoothly without extensive spinel accretion inside the furnace and the copper in the smelting slag is always below 3 wt% which can be recovered by the solidification/comminution/flotation process. The advantages of the low temperature smelting are 1) no extra fuels are required to maintain smelting temperature. Although oil jets are available on the both ends of the furnace they are rarely used; 2) low consumption of refractory. There was no significant erosion of the refractory on most part of the furnace after one and half years operation; 3) relatively higher viscosities of matte and slag allow higher pressures of the bottom blown gases to be used; 4) higher grade matte can be produced at lower temperature at a given oxygen partial pressure.

Autogenous Smelting Autothermal operation has been achieved in the bottom blown furnace at Dongying Fangyuan Nonferrous Metals for smelting of normal copper concentrate. This not only reduces energy consumption but also significantly decrease CO2 emission. It was the unique design of the bottom blown plus high concentration oxygen made the process possible to be autogenous smelting. The reasons include 1) low temperature operation does not require too much energy; 2) high Fe/SiC>2 ratio results in low slag volume for less heat loss; 3) high concentration oxygen reduces the heat loss associated with the off-gas; 4) most of the oxidization reactions occur in the bottom part of the furnace so that the heat generated from these reactions can be efficiently absorbed by the matte and slag.

References

1. V. Ramachandran, C. Diaz, T. Eltringham, C.Y. Jian, T. Lehner, PJ. Mackey, CJ. Newman, and A.V. Tarasov, "Primary Copper Production - A Survey of Operating World Copper Smelters", Copper-Cobre 2003, Vol. IV (Book 1), Ed. C. Diaz et al., MetSoc of CIM, 2003, 3-106.

2. S. He, "SKS Copper Smelting", l" Symp. On Bath Smelting Technology and Equipments, 2007, 105-111.

3. C. W. Bale, P. Chartrand, S. A. Decterov, G. Eriksson, K. Hack, R. B. Mahfoud, J. Melancon, A.D. Pelton and S. Petersen, 2002, FactSage, Ecole Polytechnique, Montre al. http://www.factsage.com/.

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