Table Of Content

Flash Ironmaking This book addresses the two major issues faced by the modern steel industry: CO 2 emissions and energy consumption. The steel industry accounts for 6.7% of the anthropogenic CO emissions and consumes 6% of the total energy consumed in 2 manufacturing. In response to these critical issues, a new technology called flash ironmaking has been developed, aimed at producing iron directly from iron ore concentrate using gaseous reductants/fuels such as natural gas or hydrogen. This ironmaking technology takes advantage of the rapid reaction rate of fine particles and bypasses the palletization process. This book discusses the principles of flash ironmaking, laboratory experiments, and design and operation of a prototype flash reactor. • Provides theories and principles of ironmaking and a novel ironmaking technology. • Includes laboratory experiments to establish the kinetic feasibility of flash ironmaking. • Covers the design and operation of a prototype flash reactor as well as the design of industrial-size flash ironmaking reactors. • Describes various cases of flow sheet development, which forms the basis for process analysis and simulation. • Presents economic analysis case studies. Presenting a novel technology that addresses contemporary issues facing one of the largest manufacturing industries, this book is aimed at professionals and research- ers in metallurgy, materials engineering, manufacturing engineering, and related disciplines. Flash Ironmaking H. Y. Sohn MATLAB® is a trademark of The MathWorks, Inc. and is used with permission. The MathWorks does not warrant the accuracy of the text or exercises in this book. This book’s use or discussion of MATLAB® software or related products does not constitute endorsement or sponsorship by The MathWorks of a particular pedagogical approach or particular use of the MATLAB® software. First edition published 2023 by CRC Press 6000 Broken Sound Parkway NW, Suite 300, Boca Raton, FL 33487-2742 and by CRC Press 4 Park Square, Milton Park, Abingdon, Oxon, OX14 4RN CRC Press is an imprint of Taylor & Francis Group, LLC © 2023 H. Y. Sohn Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the validity of all materials or the consequences of their use. The authors and publishers have attempted to trace the copyright holders of all material reproduced in this publication and apologize to copyright holders if permission to publish in this form has not been obtained. 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ISBN: 978-1-032-37775-9 (hbk) ISBN: 978-1-032-37838-1 (pbk) ISBN: 978-1-003-34219-9 (ebk) DOI: 10.1201/9781003342199 Typeset in Times by codeMantra To Victoria Bee-Tuan, Berkeley Jihoon, and Edward Jihyun for their Sacrifices, Triumphs, and Love Contents Abbreviations ...........................................................................................................xv Nomenclature .........................................................................................................xvii Preface.....................................................................................................................xxi Acknowledgments ................................................................................................xxiii Author ....................................................................................................................xxv Chapter 1 Introduction ..........................................................................................1 Chapter 2 Current Technologies for Ironmaking ..................................................3 2.1 Blast Furnace Process ................................................................3 2.2 Direct Reduction Processes .......................................................7 2.3 Smelting Reduction Processes ...................................................9 2.3.1 Advantages .................................................................10 2.3.2 Disadvantages .............................................................11 Chapter 3 Issues Facing the Steel Industry .........................................................13 3.1 Raw Materials ..........................................................................13 3.2 Greenhouse Gas Emissions .....................................................13 3.3 Energy Consumption ...............................................................15 Chapter 4 Flash Ironmaking Technology – Concept Development ....................17 Chapter 5 Basic Properties and Sources of Magnetite Concentrate ...................21 Chapter 6 Principles Related to Iron Oxide Reduction .......................................23 6.1 Thermochemistry ....................................................................23 6.1.1 The First Law of Thermodynamics – Heat and Heat Capacity .............................................................23 6.1.2 Physical Changes and Heat Content ...........................24 6.1.3 Chemical Changes and Standard State ......................26 6.1.4 Standard Heat of Formation or Standard Enthalpy of Formation ...............................................27 6.1.5 Standard Heat of Combustion ....................................27 6.1.6 Hess’ Law ...................................................................27 6.1.7 Heat of Chemical Reaction ........................................28 6.1.8 Heat of Reaction at Different Temperatures ..............29 6.1.9 Adiabatic Reaction Temperature ................................31 6.1.10 Heat of Mixing ...........................................................31 vii viii Contents 6.1.11 The Second Law of Thermodynamics .......................32 6.1.12 Activity and Activity Coefficient ...............................34 6.1.13 Chemical Equilibrium ................................................37 6.1.14 Calculation of Equilibrium Composition ...................41 6.1.15 Ellingham Diagram – ∆G° – T Diagram ...................42 6.1.16 Gibbs’ Phase Rule ......................................................44 6.1.17 Stability Diagram ......................................................46 6.2 Reaction Kinetics of Fine Solid Particles with a Gas ..............47 6.2.1 Introduction ................................................................47 6.2.2 Chemically Controlled Shrinking-Core Kinetics ......49 6.2.3 Nucleation and Growth Kinetics – Avrami– Erofeev Equation ........................................................50 6.2.4 Nucleation and Growth Kinetics – Prout– Tompkins Model (Also Called the Autocatalytic Model) ........................................................................53 6.2.5 Solid-State Diffusion Model ......................................53 6.2.6 Summary of Various Solid-State Reaction Kinetics Models..........................................................55 6.2.7 Analysis of Rate Data .................................................55 6.2.7.1 The Isothermal Method ..............................57 6.2.7.2 The Direct Differential Method – Linear T-t Program .....................................57 6.2.7.3 Coats–Redfern Integral Method – Linear T-t Program .....................................57 6.2.7.4 Iso-Conversional Methods ..........................58 6.2.7.5 Sohn’s Non-Linear Temperature–Time Program ......................................................59 Chapter 7 Development of Flash Ironmaking Technology – Reduction Kinetics of Magnetite Concentrate Particles ......................................63 7.1 Materials ..................................................................................64 7.2 Experimental Apparatus ..........................................................65 7.3 Experimental Procedure ..........................................................67 7.4 Formulation of Reduction Kinetics Equation ..........................68 7.4.1 Definitions of Parameters ...........................................68 7.4.1.1 Reduction Degree .......................................68 7.4.1.2 The Amount of Excess Reducing Gas ........69 7.4.1.3 Excess Driving Force ..................................70 7.4.1.4 Particle Residence Time .............................70 7.4.2 Selection of Rate Equation .........................................72 7.4.3 Determination of the Reaction Order with Respect to Gas Partial Pressures ................................75 7.4.4 Effect of Particle Size .................................................76 7.4.5 Determination of the Activation Energy ....................78 7.4.6 Verification of the Absence of the Effects of Mass Transfer and Pore Diffusion ..............................79 Contents ix 7.5 Results of Rate Measurements and Rate Equations ................82 7.5.1 Reduction by Hydrogen: Temperature Range of 1,150°C–1,350°C ........................................................83 7.5.2 Reduction by Hydrogen: Temperature Range of 1,350°C–1,600°C .......................................................85 7.5.3 Reduction by Carbon Monoxide: Temperature Range of 1,150°C–1,350°C ........................................86 7.5.4 Reduction by Carbon Monoxide: Temperature Range of 1,350°C–1,600°C ........................................88 7.5.5 Reduction by H + CO Mixtures: Temperature 2 Range of 1,150°C–1,350°C ........................................88 7.5.6 Reduction by H + CO Mixtures: Temperature 2 Range of 1,350°C–1,600°C ........................................91 7.5.7 Summary on the Reduction Kinetics of Magnetite Concentrate Particles ................................92 7.6 Refinements of the Rate Equations for the Reduction of Concentrate Particles through Computational Fluid Dynamics Modeling ................................................................93 7.6.1 Approach and Methodology .......................................93 7.6.2 Numerical Procedure .................................................98 7.6.3 Modeling Results ........................................................99 7.6.4 Kinetics Analysis Procedure ....................................103 7.6.5 Complete Rate Equations .........................................103 7.6.5.1 Reduction by Hydrogen: Temperature Range of 1,150°C–1,350°C .......................103 7.6.5.2 Reduction by Hydrogen: Temperature Range of 1,350°C–1,600°C ......................104 7.6.5.3 Reduction by Carbon Monoxide: Temperature Range of 1,150°C–1,350°C ....106 7.6.5.4 Reduction by Carbon Monoxide: Temperature Range of 1,350°C–1,600°C ....107 7.6.5.5 Reduction of Hematite Concentrate by H or CO ...................................................107 2 7.6.5.6 Derivation for Comparison of X-vs-t of a Compound with That of an Intermediate Phase as a Separate Reactant ......................111 7.6.6 Reduction by H + CO Mixtures ...............................112 2 7.6.7 Summary and Concluding Remarks ........................120 Chapter 8 Development of Flash Ironmaking Technology – Tests in a Laboratory Flash Reactor .................................................................121 8.1 Laboratory Flash Reactor ......................................................121 8.1.1 Importance of Testing in Laboratory Flash Reactor .....121 8.1.2 Apparatus .................................................................122 8.1.3 Experimental Procedure ...........................................124