Secondary Steelmaking: Principles and Applications

Secondary Steelmaking Principles and Applications......Page 1
Dedication......Page 3
Preface......Page 4
Acknowledgments......Page 5
About the Author......Page 6
Contents......Page 7
List of Symbols with Units......Page 10
Greek Symbols......Page 12
Some Physical Constants......Page 13
1.1 History of Secondary Steelmaking......Page 14
Contents......Page 0
1.2 Trends in Steel Quality Demands......Page 15
1.3 Scientific Fundamentals......Page 18
1.4.2 Some Other Process Control Measures......Page 19
References......Page 20
2.1 Introduction......Page 21
2.2.1 Statement of the First Law......Page 22
2.2.3 Statement of the Second Law......Page 23
2.2.5 Entropy (S)......Page 24
2.3.1 Free Energy and Criterion of Equilibrium......Page 26
2.3.2 Activity, Equilibrium Constant......Page 27
2.4 DG0 for Oxide Systems......Page 29
2.5 Activity–Composition Relationships: Concentrated Solutions......Page 31
2.5.1 A Note On Solution Models for Molten Slags......Page 34
2.6.1 Activities with One Weight Percent Standard State......Page 35
2.6.2 Solute–Solute Interactions in Dilute Multicomponent Solutions......Page 37
2.7 Chemical Potential and Equilibrium......Page 41
2.7.1 Chemical Potential of Oxygen......Page 42
2.8 Slag Basicity and Capacities......Page 44
2.8.1 Optical Basicity......Page 45
2.8.2 Slag Capacities......Page 46
References......Page 48
3.1 Basics of Fluid Flow......Page 50
3.1.1 Viscosity......Page 51
3.1.2 Flow Characterization......Page 52
Equation of Continuity......Page 55
Equation of Motion......Page 56
3.1.4 Dimensionless Variables......Page 57
3.1.5 Turbulent Flow and Its Analysis......Page 58
3.2 Fluid Flow in Steel Melts in Gas-Stirred Ladles......Page 61
3.2.1 Gas Bubbles in Liquid......Page 63
3.2.2 The Plume in a Gas-Stirred Liquid Bath......Page 65
3.2.3 Flow Field in Liquid Outside the Plume......Page 71
References......Page 78
4.1 Introduction......Page 79
Secondary Steelmaking Principles and Applications......Page 102
4.2.1 Fundamentals of Mixing......Page 80
4.2.2 Variables Influencing Mixing......Page 82
The Turbulence Model......Page 84
4.3 Kinetics of Reactions among Phases......Page 85
4.3.1 Interfacial Chemical Reaction......Page 87
4.3.2 Mass Transfer......Page 88
Mass Transfer at the Solid-Fluid Interface......Page 89
Mass Transfer between Two Fluids......Page 90
4.4.1 Solid-Liquid Interactions......Page 94
4.4.2 Liquid-Liquid Interactions......Page 95
4.5 Mixing vs. Mass Transfer Control......Page 99
References......Page 101
5.1 Thermodynamics of Deoxidation of Molten Steel......Page 103
5.1.1 Thermodynamics of Simple Deoxidation......Page 107
5.1.2 Thermodynamics of Complex Deoxidation......Page 115
5.2 Kinetics of the Deoxidation of Molten Steel......Page 118
5.2.1 Kinetics of Deoxidation Reaction......Page 119
Material Balance for Oxygen......Page 124
Gradient Collision......Page 125
5.3 Deoxidation in Industry......Page 130
References......Page 139
6.1 Introduction......Page 142
6.1.1 Vacuum Degassing Processes......Page 143
6.2.1 Principal Reactions......Page 147
Reaction of Liquid Steel with the Refractory Lining......Page 149
Volatilization......Page 151
6.3.1 Fluid Flow in Ladle Degassing......Page 153
6.3.2 Fluid Flow and Circulation Rate in RH Degassing......Page 155
6.3.3 Mixing in Degasser Vessels......Page 157
6.4.1 Behavior of Gases in Industrial Vacuum Degassing......Page 158
6.4.2 Rates of Reversible Degassing Processes......Page 160
6.4.3 Kinetics of Degassing and Decarburization General Features......Page 161
6.4.4 Importance of the akm Parameter......Page 164
6.4.5 Kinetics of Desorption and Absorption of Nitrogen by Liquid Iron......Page 165
6.4.6 Kinetic Considerations for Industrial Vacuum Degassing and Decarburization......Page 169
6.5 Decarburization for Ultra-Low Carbon (ULC) and Stainless Steel......Page 172
6.5.1 Production of Ultra-Low Carbon Steel by RH-OB Process......Page 174
6.5.2 Thermodynamics of Decarburization of High-Chromium Steel Melts......Page 175
6.5.3 Argon-Oxygen Decarburization......Page 177
References......Page 178
7.1 Introduction......Page 181
7.2.2 Reaction Equilibria of Sulfur......Page 182
7.2.3 Temperature and Composition Dependence of CS......Page 185
7.2.4 Temperature and Composition Dependence of LS......Page 188
7.3.1 Introductory Remarks......Page 191
General Features......Page 193
Slag–Metal Emulsion and Reaction Rate......Page 196
Rate Equations......Page 201
Concluding Remarks on Industrial Desulfurization by Top Slag......Page 202
7.4.1 Introduction......Page 203
7.4.2 The Reactor Model......Page 207
7.4.3 Kinetic Considerations......Page 209
Rate Equations......Page 210
7.4.4 Melt–Particle Physical Interaction......Page 214
Powder Delivery and Preparation......Page 215
Typical Recommended Practice for Ultra-Low-Sulfur Steel......Page 216
References......Page 217
8.2 Gas Absorption during Tapping and Teeming from Surrounding Atmosphere......Page 219
8.2.1 General Comments on Mechanism......Page 220
8.2.2 Stream Breakup......Page 221
8.2.4 Quantitative Predictions of Oxygen and Nitrogen Absorption during Tapping and Teeming......Page 222
8.3.1 General Features......Page 224
8.3.2 Temperature Change Due to the Addition of Deoxidizers......Page 226
8.3.3 Heat Loss from Tapping/Teeming Stream......Page 228
8.3.4 Heat Loss and Thermal Stratification in a Ladle......Page 229
8.3.5 Concluding Remarks on Steel Temperature Control in Industry......Page 233
8.4.1 Low-Alloy Steels......Page 234
8.4.2 Stainless Steels......Page 237
Phosphorus Removal under Reducing Conditions......Page 238
8.5 Nitrogen Control in Steelmaking......Page 240
8.5.2 Nitrogen Control in an Electric Arc Furnace......Page 241
8.5.3 Nitrogen Absorption during Tapping and Teeming from Surrounding Air......Page 242
8.5.4 Nitrogen Absorption during Ladle Processing......Page 243
8.6 Application of Magnetohydrodynamics......Page 244
References......Page 246
9.2 Influence of Inclusions on the Mechanical Properties of Steel......Page 248
9.3 Inclusion Identification and Cleanliness Assessment......Page 250
9.4 Origin of Nonmetallic Inclusions......Page 251
9.5 Formation of Inclusions during Solidification......Page 252
9.6.2 Inclusion Modification by Rare Earth Treatment of Steel......Page 260
9.6.3 Use of Tellurium and Selenium for Inclusion Modification......Page 262
9.6.1 Inclusion Modification by Treatment of Liquid Steel with Calcium......Page 255
References......Page 263
10.2.1 Deoxidation Practice......Page 265
10.2.2 Teeming Practice......Page 266
10.3.1 General Aspects......Page 267
10.3.2 Thermodynamic Considerations of Refractory Stability and Inertness......Page 269
10.3.3 Refractories for Secondary Steelmaking......Page 271
10.3.4 Choice of Nozzle Refractory......Page 273
10.4.1 General......Page 277
10.4.2 Choice of Tundish Covering Powder......Page 278
10.4.3 Fluid Flow and Residence Time Distribution in Tundish......Page 279
10.4.4 Design and Operation of Tundish for Clean Steel......Page 282
10.4.5 Ceramic Filter Use in Tundish......Page 285
References......Page 289
11.2.1 Physical Modeling......Page 290
11.2.2 Physical Modeling of Fluid Flow in Ladles......Page 292
11.2.3 Mathematical Modeling......Page 293
Equation of Motion in Axial Direction......Page 295
Dissipation Rate of Turbulence Energy......Page 296
11.3.4 Hydrodynamic Modeling of Axisymmetric Gas Injection Operations in Ladles......Page 297
11.4.1 Governing Equation of Material Mixing......Page 299
11.4.2 Governing Equation of Thermal Energy Mixing......Page 300
11.4.3 Mixing in Axisymmetric Ladle Refining Operations......Page 301
11.5 Modeling of Heat and Mass Transfer between Solid Additions and Liquid Steel......Page 302
11.5.2 Prediction of Dissolution Rates......Page 303
11.5.3 Prediction of Subsurface Trajectory of Solid Additions......Page 304
11.5.4 Dissolution of Ferro-alloys in Axisymmetric Gas-Stirred Ladles......Page 305
11.6 Numerical Considerations......Page 306
References......Page 307